McQuay WGZ 030AW Installation Manual

Operating Manual

Water-Cooled Scroll Compressor Chillers

WGZ 030AW To WGZ 120AW, Packaged Water-Cooled Chiller WGZ 030AA To WGZ 120AA, Chiller with Remote Condenser 30 to 120 Tons, 105 to 420 kW

Software Version WGZD20102C 60 Hz, R-22, R-407C

OM WGZ-2

Group: Chiller Part Number: 331374501 Effective: March 2005 Supercedes: OM WGZ-1

Table of Contents

Introduction........................................3

General Description...............................3

Nomenclature........................................3

Water Pressure Drop..............................3

Operating Limits....................................6

Components...........................................6

Unit Configuration ............................7

Field Wiring Diagrams..........................8

Control Panel Layout ..........................10

Motor Protection Module....................10

Start-Up and Shutdown...................11

Pre Start-up.......................................... 11

Start-up................................................11

Weekend or Temporary Shutdown ......12

Start-up after Temporary Shutdown....12

Extended Shutdown.............................12

Start-up after Extended Shutdown ......13

Low Ambient Start ..............................13

Fan High Ambient Rapid Start............14

Sequence of Operation ....................14

Start-up/Compressor Staging...............14

MicroTech II Controller .................18

Controller Software Version................18

General Description.............................18

Setpoints..............................................21

Protection (Shutdown) Alarms............22

Event (Limit) Alarms...........................23

Staging Parameters..............................26

Capacity Overrides..............................26

Digital Output Control ........................27

Analog Output Control........................28

Using the Controller............................31

Menu Screens......................................34

Menu Descriptions ..............................34

Optional Controls............................51

Phase/Voltage Monitor (Optional) ......51

Hot Gas Bypass (Optional) .................51

Troubleshooting Chart.........................52

Warranty Statement........................53

Manufactured in an ISO Certified facility

"McQuay" is a registered trademark of McQuay International

Illustrations and data cover McQuay International products at the time of publication and we reserve the right to

make changes in design and construction at anytime without notice.

2 WGZ 030A through 120A OM WGZ-2

Introduction

)

General Description

McQuay Type WGZ water chillers are designed for indoor installations and are available with watercooled condensers (Model AW), or arranged for use with remote air-cooled or evaporative condensers (Model AA). Each water-cooled unit is completely assembled and factory wired before evacuation, charging and testing. They consist of hermetic scroll compressors, brazed-plate evaporator, watercooled condenser (WGZ-AW), and complete refrigerant piping.

Units manufactured for use with remote condensers (Models WGZ-AA) have all refrigerant specialties factory-mounted and connection points for refrigerant discharge and liquid lines.

Liquid line components that are included are manual liquid line shutoff valves, charging valves, filterdriers, liquid line solenoid valves, sight glass/moisture indicators, and thermal expansion valves. Other features include compressor crankcase heaters, and a MicroTech II¥ microprocessor controller.

The electrical control center includes all equipment protection and operating controls necessary for dependable automatic operation.

The compressors are not fused as standard, but can be protected by optional circuit breakers or fuses, or can rely on a field-installed, fused disconnect switch for protection.

BOOT & BIOS

BOOT Version: 3.0F BIOS Version 3.56

Manuals: Information in unit initial installation and routine maintenance is contained in Installation and Maintenance Manual IMM WGZ-2.

Nomenclature

W G Z 100 - A W

Water-Cooled

Global

Scroll Compressor

W = Water-Cooled Condenser

Design Vintage

ominal Capacity (Tons

Water Pressure Drop

Water flow rates should be maintained as closely as possible to job design values. The vessel flow rat es mu st f al l be twe en t he mi nimu m and maxi mum values shown on the appropriate evaporator and condenser curves.

Measure the water pressure drop through the vessels at field-installed pressure taps and check the flow rate using the following tables. Do not include valves or strainers in these readings.

The evaporator flow rates and pressure drops shown on the following page are for full load design purposes. The maximum flow rate and pressure drop are based on a 6-degree temperature drop. Avoid higher flow rates with resulting lower temperature drops to prevent potential control problems resulting from very small control bands and limited start up/shut off temperature changes.

The minimum flow and pressure drop is based on a full load evaporator temperature drop of 16degrees.

Minimum Part Load Flow Rates: This full load design minimum flow is not to be confused with the part load minimum flow rate that must be maintained for chillers operating in variable primary flow pumping systems. As chiller capacity drops, the flow rate is reduced proportionally. See the following table for the part load minimum flow rates.

Table 1, Minimum Part Load

WGZ Model 030 035 040 045 050 055 060 070 080 090 100 110 120

Min.Part Load GPM

30 33 38 43 47 53 58 67 74 83 91 102 113

Flow Rates

OM WGZ-2 WGZ 030A through 120A 3

Figure 1, Evaporator Pressure Drop, WGZ 030 – WGZ 120

)

Flow Rate (L/s)

1.9 2.5 3.2 3.8 4.4 5.0 5.7 6.3

12.6 18.9

25.2

31.5 37.9

44.2 120

WGZ 040

WGZ 050

WGZ 060

WGZ 080

WGZ 030

Pressure Drop (kPa)

9 8 7

Pressure Drop (ft of water)

WGZ 100 - 120

30 27

24 21

WGZ 035

WGZ 055

WGZ 090

WGZ 045

WGZ 070

WGZ

Model

030 035 040 045 050 055 060 070 080 090 100 110 120

30 40 50 60 70 80 90 100 200 300 400 500 600

Flow Rate (GPM

Minimum Flow Nominal Flow Maximum Flow

Inch-Pound S.I. Inch-Pound S.I. Inch-Pound S.I.

GPM Ft. L/S kPa GPM Ft. L/S kPa GPM Ft. L/S kPa

45.5 1.85 2.87 5.54 75.8 5.15 4.78 15.40 126.3 14.31 7.97 42.77

50.3 1.76 3.17 5.27 83.8 4.90 5.29 14.65 139.7 13.62 8.81 40.70

57.7 1.83 3.64 5.46 96.2 5.07 6.07 15.15 160.3 14.08 10.12 42.10

63.7 1.71 4.02 5.10 106.1 4.74 6.69 14.17 176.8 13.16 11.16 39.35

70.0 1.70 4.41 5.08 116.6 4.72 7.36 14.12 194.3 13.12 12.26 39.21

78.2 1.70 4.93 5.08 130.3 4.72 8.22 14.10 217.2 13.11 13.70 39.17

85.8 1.67 5.41 5.00 143.0 4.65 9.02 13.90 238.3 12.91 15.04 38.60

97.9 1.75 6.18 5.24 163.2 4.87 10.30 14.54 272.0 13.51 17.16 40.40

112.3 1.86 7.09 5.56 187.2 5.17 11.81 15.45 312.0 14.36 19.68 42.92

123.5 1.91 7.79 5.70 205.9 5.29 12.99 15.82 343.2 14.71 21.65 43.96

134.9 2.14 8.51 6.39 224.9 5.94 14.19 17.74 374.8 16.49 23.65 49.29

152.9 2.75 9.65 8.21 254.9 7.63 16.08 22.79 424.8 21.18 26.80 63.31

168.8 3.34 10.65 9.99 281.3 9.29 17.75 27.76 468.8 25.80 29.58 77.11

700

Note: Minimum, nomin a l, and maximum flows are at a 16°F, 10°F, and 6°F chilled water temperature range respectively and at ARI tons.

4 WGZ 030A through 120A OM WGZ-2

Figure 2, Condenser Pressure Drop, WGZ 030 – WGZ 120

Flow Rate (L/s)

1.9 2.5 3.2 3.8 4.4 5.0 5.7 6.3

70 60

12.6 18.9

25.2

31.5 37.9

44.2 210

180

WGZ 050, 055

WGZ 080

WGZ 090

150

120

WGZ 040, 045

Pressure Drop (kPa)

WGZ 030, 035

9 8

Pressure Drop (ft of water)

7 6

WGZ 070

WGZ 100 - 120

30 27

24 21

WGZ

Model

030 035 040 045 050 055 060 070 080 090 100 110 120

WGZ 060

30 40 50 60 70 80 90 100 200 300 400 500 600

Flow Rate (GPM)

700

Minimum Flow Nominal Flow Maximum Flow

Inch-Pound S.I. Inch-Pound S.I. Inch-Pound S.I.

GPM Ft. L/S kPa GPM Ft. L/S kPa GPM Ft. L/S kPa

56.9 2.66 3.59 7.96 94.8 7.40 5.98 22.11 158.0 20.55 9.97 61.43

62.8 3.25 3.96 9.71 104.7 9.02 6.61 26.97 174.5 25.07 11.01 74.93

72.2 2.83 4.55 8.45 120.3 7.85 7.59 23.46 200.5 21.80 12.65 65.17

79.6 3.43 5.02 10.26 132.6 9.54 8.37 28.51 221.0 26.49 13.94 79.18

87.5 3.02 5.52 9.02 145.8 8.38 9.20 25.05 243.0 23.28 15.33 69.58

97.7 3.77 6.17 11.26 162.9 10.46 10.28 31.27 271.5 29.06 17.13 86.85

107.3 3.38 6.77 10.11 178.8 9.39 11.28 28.07 298.0 26.09 18.80 77.97

122.4 3.45 7.72 10.31 204.0 9.58 12.87 28.64 340.0 26.62 21.45 79.56

140.4 3.92 8.86 11.72 234.0 10.89 14.76 32.56 390.0 30.26 24.61 90.45

154.4 3.95 9.74 11.81 257.4 10.97 16.24 32.80 429.0 30.48 27.07 91.11

168.7 3.55 10.64 10.62 281.1 9.87 17.73 29.50 468.5 27.41 29.56 81.94

191.2 4.56 12.06 13.64 318.6 12.68 20.10 37.89 531.0 35.21 33.50 105.26

211.0 5.56 13.31 16.61 351.6 15.44 22.18 46.15 586.0 42.89 36.97 128.19

OM WGZ-2 WGZ 030A through 120A 5

Operating Limits

• Maximum allowable condenser water pressure is 232 psig (1599 kPa).

• Maximum allowable cooler water pressure is 363 psig (2509 kPa).

• Maximum design saturated discharge temperature is 140°F (60°C).

• Maximum allowable water temperature to cooler in a non-operating cycle is 100°F

(37.8°C). Maximum entering water temperature for operating cycle is 90°F (32.2°C) (during system changeover from heating to cooling cycle).

• Minimum leaving water temperature from the cooler without freeze protection is 40°F

(4.4°C).

• Minimum entering tower condenser water temperature is 60°F (15.6°C).

Components

Figure 3, Compressor Locations

Evaporator and

423

Evaporator

Condenser Connections

Circuit 2 Circuit 1

Control Panel

Table 2, Major Components

Unit

Size

030 ZR90K3 ZR90K3 ZR11M3 ZR11M3 AC250-70DQ C1010-046 OVE-20-CP100 OVE-20-CP100 035 ZR11M3 ZR11M3 ZR11M3 ZR11M3 AC250-78DQ C1010-046 OVE-20-CP100 OVE-20-CP100 040 ZR12M3 ZR12M3 ZR12M3 ZR12M3 AC250-90DQ C1010-058 OVE-20-CP100 OVE-20-CP100 045 ZR12M3 ZR12M3 ZR16M3 ZR16M3 AC250-102DQ C1010-058 OVE-30-CP100 OVE-30-CP100 050 ZR16M3 ZR16M3 ZR16M3 ZR16M3 AC250-114DQ C1010-070 OVE-30-CP100 OVE-30-CP100 055 ZR16M3 ZR16M3 ZR19M3 ZR19M3 AC250-130DQ C1010-070 OVE-30-CP100 Y929-VCP100 060 ZR19M3 ZR19M3 ZR19M3 ZR19M3 AC250-146DQ C1410-078 Y929-VCP100 Y929-VCP100 070 ZR19M3 ZR19M3 ZR250KC ZR250KC AC250-166DQ C1410-090 OVE-40-CP100 OVE-40-CP100 080 ZR250KC ZR250KC ZR250KC ZR250KC AC250-194DQ C1410-098 OVE-40-CP100 OVE-40-CP100 090 ZR250KC ZR250KC ZR300KC ZR300KC AC250-230DQ C1410-110 OVE-55-CP100 OVE-55-CP100 100 ZR300KC ZR300KC ZR300KC ZR300KC AC250-250DQ C1410-122 OVE-55-CP100 OVE-55-CP100 110 ZR300KC ZR300KC ZR380KC ZR380KC AC250-250DQ C1410-122 OVE-55-CP100 OVE-70-CP100 120 ZR380KC ZR380KC ZR380KC ZR380KC AC250-250DQ C1410-122 OVE-70-CP100 OVE-70-CP100

System #1 System #2 Expansion Valve

Comp. #1 Comp. #3 Comp. #2 Comp. #4

Evap.

Vessel

Size

Cond.

Vessel

Size

System #1 System #2

6 WGZ 030A through 120A OM WGZ-2

Unit Configuration

The chiller unit has two refrigerant circuits, two tandem scroll compressors (total of four), a single two-circuited brazed plate evaporator, a single two-circuited water-cooled condenser, interconnecting refrigerant piping and a control panel with associated sensors and transducers.

Figure 4, Schematic Piping Diagram (One of Two Circuits)

Chilled

Water

LWT

Evaporator

Legend:

Temperature Sensor

Pressure Transducer

Pressure (High Pressure Cutout)

Condenser

F-D

Comp

Relief Valve Schrader Fitting Thermal Expansion Valve

Comp

Condenser

Water

Temperataure Sensor, Leaving

LWT

Chilled Water Control

Solenoid Valve

F-D

Filter-Drier

Sight Glass / Moisture Indicator

Charging Valve

Angle Valve

Ball Valve

OM WGZ-2 WGZ 030A through 120A 7

Field Wiring Diagrams

SCO

Figure 5, WGZ 030AW – 120AW Field Wiring Diagram

3 PHASE

POWER

SUPPLY

FIELD

SUPPLIED

OPTION

CONTROL POWER

FACTORY SUPPLIED ALARM

FIELD WIRED

LARM BELL

OPTION

REMOTE STOP SWITCH

(BY OTHERS)

ICE MODE SWITCH

(BY OTHERS)

CHW FLOW SWITCH

--MANDATORY-(BY OTHERS)

CDW FLOW SWITCH

--MANDATORY-(BY OTHERS)

4-20 MA FOR

CHW RESET

(BY OTHERS)

4-20 MA FOR DEMAND LIMIT (BY OTHERS)

NNECT

(BY OTHERS)

DISCONNECT

(BY OTHERS)

120VAC

CDW PUMP RELA Y

(BY OTHERS)

120 VAC 1.0 AMP MAX

TOWER FAN #1 COIL

(BY OTHERS)

120 VAC 1.0 AMP MAX

ALARM BELL

RELAY

TIME CLOCK

UNIT MAIN

TERMINAL BLOCK

FUSED CONTROL

CIRCUIT

TRANSFORMER

10A

FUSE

(BY OTHERS)

CHW PUMP RELA Y

(BY OTHERS)

120 VAC 1. 0 AMP MAX

TOWER FAN #2 COI L

(BY OTHERS)

120 VAC 1. 0 AMP MAX

OFF

UTO

MANUAL

OFF

UTO

MANUAL

NOR. OPEN PUMP A UX. CONTACTS (OPTIONAL)

NOR. OPEN PUMP AUX.

CONTACTS (OPTIONAL)

GND LUG

120 VAC

TB1

CONTROLLER

J15-N08

TB1-12

J16-N09

TB1-12

J16-N10

TB2

TO COMPRESSOR(S)

TB1-20

CONTROL CIRCUIT

FUSE

2 11 14

GND

40 53

IF REMOTE STOP CONTROL

897

IS USED, REMOVE LEAD 897

FROM TERM 40 TO 53.

IF ICE MODE IS USED

900

REMOVE LEAD

FROM TERM 42 TO 55.

33 43

CONTROLLER

Rx-/Tx-

Rx+/Tx+

53 38 48 49

GND

38 50 51

GND

120VAC

J11

GND

120 VAC

COMMUNICATIO

2 3

330258901-R4

PORT

8 WGZ 030A through 120A OM WGZ-2

Figure 6, WGZ 030AA – 120AA Field Wiring Diagram (Remote Condenser)

UNIT MAIN

3 PHASE

FIELD

SUPPLIED

OPTION

REMOTE STOP SWITCH

NOTE: CONDENSER FAN MOTORS CAN ALSO BE CONTROLLED BY PRESSURE SWITCHES ON THE CONDENSER.

CONTROL POWER

(BY OTHERS)

ICE MODE SWITCH

(BY OTHERS)

CHW FLOW SWITCH

4-20 MA FOR

CHW RESET

(BY OTHERS)

4-20 MA FOR DEMAND LIMIT (BY OTHERS)

330259001-R4

DISCONNECT

(BY OTHERS)

POWER SUPPLY

FUSED CONTROL TRANSFORMER

DISCONNECT

(BY OTHERS)

120VAC

FACTORY SUPPLIED ALARM

FIELD WIRED

ALARM BELL

OPTION

ALARM BELL RELAY

TIME

CLOCK

UTO ON

--MANDATORY--

(BY OTHERS)

LIQUID LINE #1 SOLENOID

LIQUID LINE #2 SOLENOID

OPTIONAL

HOT GAS BYPASS #1 SOLENOID

HOT GAS BYPASS #2 SOLENOID

FAN MOTOR #1 COIL

FAN MOTOR #2 COIL

FAN MOTO R #3 COIL

FAN MOTO R #4 COIL

FAN MOTOR #5 COIL

FAN MOTO R #6 COIL

FAN MOTO R #7 COIL

FAN MOTOR #8 COIL

TERMINAL BLOCK

CIRCUIT

10A

FUSE

(BY OTHERS)

CHW PUMP RELAY

(BY OTHERS)

120 VAC 1.0 AMP MAX

OFF

UTO

MANUAL

OFF

MANUAL

NOR. OPEN PUMP AUX. CONTACTS (OPTIONAL)

24 VAC AMP MAX

(BY OTHERS)

120 VAC 1.0 AMP MAX

(BY OTHERS)

120 VAC 1.0 AMP MAX

(BY OTHERS)

120 VAC 1.0 AMP MAX

(BY OTHERS)

120 VAC 1.0 AMP MAX

(BY OTHERS)

120 VAC 1.0 AMP MAX

(BY OTHERS)

VAC 1.0 AMP MAX

120 VAC

(BY OTHERS)

GND LUG

TB1

2 11 14

TB2

38 48

38 50

TB3

CONTROLLER

J15-N08

TB1-12

J16-N09

J16-N010

J16-N011

J18-N013

J22-N016

J22-N017

J22-N018

TO COMPRESSOR(S)

TB1-20

CONTROL

CIRCUIT

FUSE

120 VAC

120VAC

GND

IF REMOTE STOP CONTROL

897

IS USED, REMOVE LEAD 897 FROM TERM 40 TO 53.

IF ICE MODE IS USED

900

REMOVE LEAD FROM TERM 42 TO 55.

CONTROLLER

J11

GND

1 2 3

24 VAC

120 VAC

Rx-/TxRx+/Tx+

GND

COMMUNICATIO

PORT

OM WGZ-2 WGZ 030A through 120A 9

Control Panel Layout

Figure 7, Typical Control Panel

MicroTech II Unit

Controller

(3) 24V Controller Transformers

Terminal Strips

S1, PS1, PS2

(4) Compressor

Grounding Lug

Switches

Contactors

110V Control

Space for Optional Circuit Breakers and Multi-point Connection

Disconnect Switch

NOTES:

1. Additional space provided in the upper right section for extra components required for optional multiple point power connection and optional circuit breakers.

2. Front door has opening on top for access to the MicroTech II controller for viewing display and making keypad entries without opening the panel door.

Motor Protection Module

The motor protection system consists of an external control module, located on each compressor, connected to a series of thermistors located in the motor windings and the compressor discharge port. If the windings experience an over-temperature condition or the discharge temperature is excessive, the module will trip and shut off the compressor for a 30-minute time delay.

10 WGZ 030A through 120A OM WGZ-2

Start-Up and Shutdown

Pre Start-up

1. The chilled-water system should be flushed and cleaned. Proper water treatment is required to prevent corrosion and organic growth.

2. With main disconnect open, check all electrical connections in control panel and starter to be sure they are tight and provide good electrical contact. Although connections are tightened at the factory, they can loosen enough in shipment to cause a malfunction.

3. Check and inspect all water piping. Make sure flow direction is correct and piping is made to correct connection on evaporator and condenser.

4. Open all water flow valves to the condenser and evaporator.

5. Flush the cooling tower and system piping to be sure the system is clean. Start evaporator pump and manually start condenser pump and cooling tower. Check all piping for leaks. Vent the air from the evaporator and condenser water circuit, as well as from the entire water system. The cooler circuit should contain clean, treated, noncorrosive water.

6. Check to see that the evaporator water thermostat sensor is securely installed.

7. Making sure control stop switch S1 is open (off) and pumpdown switches PS1 and PS2 are on “manual pumpdown,” place the main power and control disconnect switches to “on.” This will energize the crankcase heaters. Wait a minimum of 12 hours before starting the unit.

8. Check compressor oil level. Prior to start-up, the oil level should cover at least onethird of the oil sight glass located in the equalizing line between the compressors or on the compressor.

9. Note the water pressure drop across evaporator and condenser on pages Error! Bookmark not defined. and Error! Bookmark not defined. and check that water flow is correct per the system design flow rates.

10. Check the actual line voltage to the unit to make sure it is the same as called for on the compressor nameplate, within + 10%, and that phase voltage unbalance does not exceed 3%. Verify that adequate power supply and capacity is available to handle load.

11. Make sure all wiring and fuses are of the proper size. Also make sure that all interlock wiring is completed per McQuay diagrams.

12. Verify that all mechanical and electrical inspections by code authorities have been completed.

13. Make sure all auxiliary load and control equipment is operative and that an adequate cooling load is available for initial start-up.

Start-up

1. Open the compressor discharge shutoff valves until backseated. Always replace valve seal caps.

2. Open the two manual liquid line shutoff valves.

3. Check to see that the unit circuit breakers are in the “off” position.

4. Check to see that the pumpdown switches, PS1 and PS2, are in the “manual pumpdown” position and the control system switch S1 is in the “off” position.

5. Put the main power and control circuit disconnects to the “on” position.

OM WGZ-2 WGZ 030A through 120A 11

6. Verify crankcase heaters have operated for at least 12 hours prior to start-up. Crankcase should be warm to the touch.

7. Check that the MicroTech II controller is set to the desired chilled water temperature.

8. Start the system auxiliary equipment for the installation by turning on the time clock, ambient thermostat and/or remote on/off switch and water pumps.

9. Check resets of all equipment protection controls.

10. Switch on the unit circuit breakers.

11. Set pumpdown switches PS1 and PS2 to “auto” for restart and normal operation.

12. Start the system by setting the system switch S1 to on.

13. After running the unit for a short time, check the oil level in each compressor crankcase, rotation of condenser fans (if any), and check for flashing in the refrigerant sight glass.

14. After system performance has stabilized, it is necessary that the “Compressorized Equipment Warranty Form” (Form No. 206036A) be completed to establish commencement of the warranty period. Be sure to list the pressure drop across both vessels. This form is shipped with the unit and after completion should be returned to the McQuayService Department through your sales representative.

Weekend or Temporary Shutdown

Move pumpdown switches PS1 and PS2 to the “manual pumpdown” position. After the compressors have pumped down, turn off the chilled water pump. Note: With the unit in this condition, it will not restart until these switches are turned back on. The unit has onetime pumpdown. It is important that the compressors pump down before the water flow to the unit is interrupted to avoid freeze-up in the evaporator.

Leave S1 on and power to the unit so that the crankcase heaters will remain energized.

Start-up after Temporary Shutdown

1. Start the water pumps.

2. With the control system switch S1 in the “on” position, move the pumpdown switches PS1 and PS2 to the “auto pumpdown” position.

3. Observe the unit operation for a short time, noting unusual sounds or possible cycling of compressors.

4. Check compressor crankcase heaters.

Extended Shutdown

1. Close the manual liquid line shutoff valves.

2. After the compressors have pumped down, turn off the water pumps.

3. Turn off all power to the unit.

4. Move the control service switch S1 to the “off” position.

5. Close the discharge shutoff valves on the compressor(s) and the liquid outlet valves at the condenser.

6. Tag all opened disconnect switches to warn against start-up before opening the compressor suction and discharge valves.

7. Drain all water from the unit evaporator, condenser, and chilled water piping if the unit is to be shut down during the winter and exposed to below freezing temperatures. Do not leave the vessels or piping open to the atmosphere over the shutdown period.

12 WGZ 030A through 120A OM WGZ-2

Start-up after Extended Shutdown

1. Inspect all equipment to see that it is in satisfactory operating condition.

2. Remove all debris that has collected on the surface of the condenser coils (remote condenser models) or check the cooling tower, if present.

3. Open the compressor discharge valves until backseated. Always replace valve seal caps.

4. Open the manual liquid line shutoff valves.

5. Check circuit breakers. They must be in the “off” position.

6. Check to see that the pumpdown switches PS1 and PS2 are in the “manual shutdown” position and the control system switch S1 is in the “off” position.

7. Put the main power and control circuit disconnects to the “on” position.

8. Allow the crankcase heaters to operate for at least 12 hours prior to start-up.

9. Start the chilled water pump and purge the water piping as well as the evaporator in the unit.

10. Start the system auxiliary equipment for the installation by turning on the time clock, ambient thermostat and/or remote on/off switch.

11. Check that the MicroTech II controller is set to the desired chilled water temperature.

12. Check resets of all equipment protection controls.

13. Switch the unit circuit breakers to “on.”

14. Start the system by setting the system switch S1 to “on.”

CAUTION

Most relays and terminals in the control center are powered when S1 is

closed and the control circuit disconnect i s on. Therefore, do not close S1

until ready for start-up or serious equipment damage can occur.

15. Set pumpdown switches PS1 and PS2 to the “auto pumpdown” position for restart and normal operation.

16. After running the unit for a short time, check the oil level in the compressor oil sight glass or in the compressor’s equalizing lines for flashing, indicating possible refrigerant in the oil.

Low Ambient Start

The low ambient start logic is for starting units with remote air-cooled condensers during periods of low ambient air temperatures.

A low ambient start takes place if the saturated condenser temperature is less than 85.0°F when the first compressor starts. The low ambient start is active for a time defined by the Low OAT Start Timer set point. This set point is found on screen three in the alarm set points menus.

During the low ambient start, the freezestat logic for the low-pressure stop alarm and the low-pressure events are disabled. The low-pressure stop alarm can still be triggered if the evaporator pressure drops below 5.0 psi at any time while the circuit is in the ‘Run’ state. Also, during the low ambient start, the second compressor is not allowed to start. The evaporator pressure is checked at the end of the low ambient start time frame. If the pressure is less than the low pressure unload set point, then the low ambient start is not successful and the compressor will shut off. This will not be a manual reset alarm until three consecutive attempts have failed. The circuit alarm triggered after the third failed

OM WGZ-2 WGZ 030A through 120A 13

attempt is a Low OAT Restart fault. The Low OAT Restart faults are Circuit alarms so each circuit will attempt to start either compressor three times before the Low OAT Restart fault is indicated.

Fan High Ambient Rapid Start

The following logic exists to get condenser fans started earlier than normal during unit starts with warm ambient air temperatures.

• If the outside air temperature higher than 75.0°F the condenser fan staging logic changes to bring on the first fan on when the condenser pressure is greater than 140 psi.

• The standard condenser fan staging logic would start the first condenser fan when the condenser pressure is higher than 200.0 psi.

• The last condenser fan on each circuit will not shut down until the condenser pressure drops below 140.0 psi regardless of the outside air temperature

Sequence of Operation

The following sequence of operation is typical for WGZ water chiller models. The sequence can vary slightly depending upon options.

Compressor Heaters

With the control circuit power on and the control stop switch S1 off, 115V power is applied through the control circuit fuse Fl to the compressor crankcase heaters HTR1, HTR2, HTR3, and HTR4.

Start-up/Compressor Staging

When compressors start and stop. Stage Up Temp is the LWT temperature at which the next compressor to start will stage up

(start) after at least one compressor on the unit has started and is running. Start Up Temp is the LWT at which the first compressor starts. The start up temperature

equals the stage up temperature plus the Start Delta temperature. A high Start Delta will keep the unit off longer and reduce unit cycling at low loads. However, this high Start Delta will cause a larger excursion from the LWT setpoint before the unit starts.

Stated another way, the Start Delta is the number of degrees above the Evap LWT setpoint, plus ½ the Dead Band, that determines when the first compressor starts. The Start Delta is in effect for only the first start after all compressors have been off. Additional compressor starts and stops are determined by the LWT in respect to the dead band only. The dead band is automatically set of 30% of the EvapDeltaT selected in menu 3. The following sequence would occur for the settings shown below:

EvapDelta T=10.0°F Dead Band=3.0°F StartDelta=5.0°F StopDelta=2.0°F LWT=40.0°F

Figure 8, Staging/Starting Temperatures

EWT

Evap Delta-T Set

LWT Set

50.0°F

10.0°F

40.0°F

Start Del ta T

½DB

46.5°

41.5°

40.0°

38.5°

For a warm start-up (no compressors running), the first compressor will start at any temperature above

46.5°F. Each subsequent compressor will start after the Stage Up Timer has timed out and if the temperature is above the

14 WGZ 030A through 120A OM WGZ-2

dead band, 41.5°F in this case. If the LWT stays above 41.5°F, all of three remaining compressors will eventually stage on after the Stage Up Timer times out between each stage.

At some point, the chilled water temperature will be dropping and begin to approach the point when compressors should begin staging off, which is the LWT setpoint minus ½ of the Dead Band, 38.5°F in this case. If the LWT remains below LWT setpoint minus ½ Dead Band and the Stage Down Timer times out, additional compressor will stage off. The last compressor will stage off when the LWT falls below the LWT Setpoint minus ½ the Dead Band minus the Stop Delta T. The stop Delta T is in effect for only the last compressor running.

If the temperature climbs above 38.5°F all running compressors will remain on. No compressor staging occurs within the Dead Band. The next-on compressor will start when the chilled water temperature reaches 41.5°F and the Stage Up Timer times out.

However, in some circumstances this methodology can cause the LWT to drop to dangerously low levels, with the evaporating temperature below the freeze point, before stopping. In the example shown in Figure 8, the Shutdown Temp (last compressor off) would be 36°F.

This would result in a refrigerant evaporating temperature approaching freezing, so the rule is amended to read:

If the Cool Leaving Water Temperature (LWT) set point is less than half the Control Band above 39.0° F the Stage Down temperature is calculated as:

Stage Down Temperature = Cool LWT – (Cool LWT - 39.0

Shutdown Temperature = Cool LWT – (Cool LWT - 39.0

F), and the

F) – Stop Delta T

This keeps the Stage Down Temp above 39°F and the Shutdown Temp above 36°F, as the maximum Stop Delta T allowed is 3-degrees.

Which compressor starts and stops. One compressor per circuit will start before starting the second compressor on any circuit. In other words, the compressor with the lowest number of starts will start first. The compressor with the lowest number of starts on the other circuit will start next, so that one compressor on each circuit will be running. The third compressor on will be the compressor on either circuit with the fewest starts. The remaining compressor will be the last on. If a circuit is unavailable for any reason, the second compressor. on the operating circuit will stage on. Only two compressors (on the one circuit) will be operating.

There is a 150 second delay after power-up before any compressor is allowed to start. When staging down, one compressor on each circuit will be left on until each circuit has

only one compressor running. In other words, the compressor, on either circuit, with the most run-hours will stop first. The compressor with the most run-hours on the other circuit will stop next. One compressor on each circuit will be running. The third compressor off will be the one, on either circuit, with the most run-hours. The remaining compressor will be the last off. See the following description of pumpdown.

Table 3, Staging in Cool and Glycol Mode

Description Occurs When: Action Taken

Stage #1 ON (See Notes Below) Stage #2 ON After Stage Up Delay times out then, LVG Evap

Stage #3 ON After Stage Up Delay times out, then LVG Evap Stage #4 ON After Stage Up Delay times out then, LVG Evap

Lvg Evap T > Evap LWT SP + (DB/ 2) + S t artup

Delta T T > Evap LWT SP + (DB/2) T > Evap LWT SP + (DB/2) T > Evap LWT SP + (DB/2)

Available compressor with l east starts, ON Available compressor on the other circuit with least starts, ON Available compressor on ei ther circuit with least starts, ON Remaining compressor, ON

Continued next page.

OM WGZ-2 WGZ 030A through 120A 15

Description Occurs When: Action Taken

Stage #4 OFF After Stage Down Delay times out then, LVG

Evap T < Evap LWT SP – (CB/2)

Stage #3 OFF After Stage Down Delay times out then, LVG

Evap T < Evap LWT SP – (DB/2)

Stage #2 OFF After Stage Down Delay times out then, LVG

Evap T < Evap LWT SP – (DB/2)

Stage #1 OFF After Stage Down Delay times out then, LVG

Evap T < Evap LWT SP – (DB/2)-StopDelta T

Note 1: DB (Dead Band) = Evap W ater Delta T x .3

Compressor with most run hours, OFF Compressor on the other ci rcuit with most run hours, OFF Compressor on either circuit with most run hours, OFF Remaining compressor, OFF

Manual Compressor Disable Logic

Logic is available that allows the operator to manually enable and disable compressors. When a compressor is disabled, it is considered unavailable to start in the staging logic. This allows a damaged compressor to be taken offline while the remaining compressor can still provide some cooling

• The Compressor Disable set points are found on Compressor Set Points screens three and four.

• A running compressor cannot be disabled until it has been shutdown.

• If all of the compressors on a circuit are disabled, then the circuit will be disabled.

• If both circuits have all of their compressors disabled, then the Unit State will remain

Off

Automatic Pumpdown

WGZ units are equipped with single pumpdown control. When the last compressor running on either circuit is ready to shut off, the liquid line solenoid valve (LLSV) is closed first and the compressor continues to run until the pumpdown pressure is reached, at which time the compressor shuts off. The shut off pressure is set at 15 psi below the Low Evaporator pressure Unload setpoint.

When the first compressor on a circuit starts, the LLSV opens simultaneously.

Manual Pumpdown

When the Pumpdown Switch is in the pumpdown position, Compressor #3 or #4 (depending on circuit) will shut off. Then the Liquid Line and Hot Gas Bypass Valves will close. The operating compressor will pump out the refrigerant. When the Suction Pressure is at 40 psig, the compressor will stop.

Chilled Water and Condenser Water Pumps

The chiller MicroTech II controller can be programmed to start and stop the system chilled water and condenser water pumps. They may also be controlled by the BAS or manually. Programming directions and the sequence of operation can be found beginning on page 30.

Cooling Tower Control

The cooling tower fans and/or the tower bypass valve can be controlled by the MicroTech II controller. This provides a simple and direct method to control the unit’s discharge pressure. Programming directions and the sequence of operation can be found on page 44. Some means of discharge pressure control must be installed if the condenser water temperature can fall below 60°F (16°C).

16 WGZ 030A through 120A OM WGZ-2

Condenser Fan Control

Model AA chillers equipped with air-cooled or evaporative-cooled condensers usually require some form of discharge pressure control. The MicroTech II controller can be programmed to provide this function by cycling condenser fans based on the unit discharge pressure. Directions on the pressure settings can be found on page 44.

ICE

In ICE mode, the compressors stage to 100% load until the LWT is less than the ICE LWT SP. Then Compressors #3 and #4 shut down. Following that, Compressors #1 and #2 shut down after going through normal pumpdown on both circuits. There is a programmable, start-to-start, Ice Mode Start Delay that limits the frequency of starts when in the ice mode. The timer can be manually cleared to force a restart.

OM WGZ-2 WGZ 030A through 120A 17

MicroTech II Controller

Controller Software Version

This manual is based on software version WGZD20102B. The “02B” is the version descriptor. The version installed in a unit can be viewed by pressing the MENU and ENTER keys simultaneously. Then pressing MENU to return to the regular menu screen.

General Description

The MicroTech II controller’s state-of-the-art design will not only permit the chiller to run more efficiently but will also simplify troubleshooting if a system failure occurs. Every MicroTech II controller is programmed and tested prior to shipment to assist in a troublefree start-up. The MicroTech II controller can be used to cycle fans on remote air-cooled condensers for head pressure control when the setpoint Water Cooled=N is selected in one of the setpoint menu screens. Water Cooled=Y sets the chiller for operation with the watercooled condenser.

Operator Friendly

The MicroTech II controller menu structure is separated into three distinct categories, which provide the operator or service technician with a full description of 1) current unit status, 2) control parameters (setpoints), and 3) alarms. Security protection prevents unauthorized changing of the setpoints and control parameters.

The MicroTech II controller continuously performs self-diagnostic checks, monitoring all system temperatures, pressures and protection devices, and will automatically shutdown a compressor, a refrigerant circuit or the entire unit should a fault occur. The cause of the shutdown and date stamp are retained in memory and can be easily displayed in plain English for operator review, which is an extremely useful feature for troubleshooting. In addition to displaying alarm diagnostics, the MicroTech II chiller controller also provides the operator with a warning of pre-alarm conditions.

Staging

The four scroll compressors are staged on and off as a function of leaving chilled water temperature, number of starts and run-hours. See Sequence of Operation.

Equipment Protection

The unit is protected by alarms that shut it down and require manual reset, and also by limit alarms that limit unit operation in response to some out-of-limit condition. Shut down alarms activate an alarm signal that can be wired to a remote device.

Unit Enable Selection

Enables unit operation from local keypad or digital input.

Unit Mode Selection

Selects standard cooling, ice, glycol, or test operation mode.

18 WGZ 030A through 120A OM WGZ-2

Keypad/Display

A 4-line by 20-character/line liquid crystal display and 6-key keypad is mounted on the unit controller. Its layout is shown below.

Figure 9, Keypad and Display in MENU Mode

Air Condi ti oni ng

ALARM

VIEW

SET

Menu Key Key to Screen

Arrow Keys

"Enter" Key

The four arrow keys (UP, DOWN, LEFT, RIGHT) have three modes of use.

1. Scroll between data screens as indicated by the arrows (default mode).

2. Select a specific data screen in a hierarchical fashion using dynamic labels on the right side of the display (this mode is entered by pressing the MENU key).

3. Change field values in edit mode according to the following table:

LEFT Default RIGHT Cancel UP Increment DOWN Decrement These four edit functions are indicated by one-character abbreviation on the right side of the display (this mode is entered by pressing the ENTER key).

Inputs/Outputs

Table 4, Analog Inputs

C1 = Refrigerant Circuit #1, C2 = Refrigerant Circuit #2, UT = Unit

# Description Type Signal Source Range

1 Evaporator Refrigerant Pressure #1 C1 0.5 – 4.5 VDC (NOTE 1) 0 to 132 psi 2 Evaporator Refrigerant Pressure #2 C2 0.5 – 4.5 VDC (NOTE 1) 0 to 132 psi 3 Condenser Refrigerant Pressure #1 C1 0.5 – 4.5 VDC (NOTE 1) 3.6 to 410 psi

4 Leaving Evaporator Water Temperature UT

Condenser Entering or Outside

Ambient Temperature (NOTE 2) 6 Condenser Refrigerant Pressure #2 C2 0.1 to 0.9 VDC 7 Reset of Leaving Water Temperature UT 4-20 mA Current 0-(10 to 60°F) 8 Demand Limit UT 4-20 mA Current 0-100 % Load

9 Compressor Suction Temperature #1 C1

10 Compressor Suction Temperature #2 C2

NOTES:

1. Value at the converter board input. Value at the converter board output is 0.1 VDC – 0.9 VDC.

2. If Water Cooled = Y, then Entering Condens er. If Water Cooled = N, then Outside Ambient.

Thermister (10k at 77°F, 25°C)

-58 to 212°F

3.6 to 410 psi

-58 to 212°F

OM WGZ-2 WGZ 030A through 120A 19

Table 5, Analog Outputs

# Description Output Signal Range

1 Cooling Tower Bypass Valve Position 0 to 10 VDC 0 to 100% Open 2 Cooling Tower VFD Speed 0 to 10 VDC 0 to 100%

Table 6, Digital Inputs

C1 = Refrigerant Circuit #1, C2 = Refrigerant Circuit #2, UT = Unit

# Description Type Signal Signal

1 Unit OFF Switch UT 0 VAC (Stop) 24 VAC (Auto) 2 Pump Down Switch #1 C1 0 VAC (Stop) 24 VAC (Start) 3 Evaporator Water Flow Switch UT 0 VAC (No Flow) 24 VAC (Flow) 4 Motor Protection #1 C1 0 VAC (Fault) 24 VAC (No Fault) 5 Open 6 Pump Down Switch #2 C2 0 VAC (Stop) 24 VAC (Start) 7 Motor Protection #2 C2 0 VAC (Fault) 24 VAC (No Fault) 8 Open

9 Phase Voltage Fault #1 (See Note 1) C1 0 VAC (Fault) 24 VAC (No Fault) 10 Phase Voltage Fault #2 (See Note 1) C2 0 VAC (Fault) 24 VAC (No Fault) 11 Ground Fault Prot. #1 (See Note 2) C1 0 VAC (Fault) 24 VAC (No Fault) 12 Ground Fault Prot. #2 (See Note 2) C2 0 VAC (Fault) 24 VAC (No Fault) 13 Remote Start/Stop UT 0 VAC (Stop) 24 VAC (Start) 14 Condenser Water Flow Switch UT 0 VA C (No Fl ow) 24 VAC (Flow)

15 Mechanical High Pressure #1 C2 16 Mechanical High Pressure #2 C2

17 Ice Mode Switch UT 0 VAC (Normal) 24 VAC (Ice) 18 Open

Note 1: See Equipment Protection Alarms Table for “Phase Voltage Protection”. Units with single point electrical connection will have one PVM with Inputs 9 and 10 wired together. Units with multiple point connection will have two PVM’s with Input 9 for Electrical Circuit #1 and Input 10 for Electrical Circuit #2.

Note 2: See Equipment Protection Alarms Table for “Ground Fault Protection”. Units with single point electrical connection will have one GFP with Inputs 11 and 12 wired together. Units with multiple point connection will have two GFP’s with Input 11 for Electrical Circuit #1 and Input 12 for Electrical Circuit #2.

0 VAC (High Pressure/Off) 0 VAC (High Pressure/Off)

24 VAC (OK ) 24 VAC (OK )

Table 7, Digital Outputs

C1 = Refrigerant Circuit #1, C2 = Refrigerant Circuit #2, UT = Uni t

# Description Type Load Output OFF Output ON

1 Alarm 2 E vaporat or Water Pump UT Pump Contactor Pump OFF Pump ON

Condenser Fan #1 – Water Cooled

= N / Condenser Water P ump –

Water Cooled = Y 4 Motor Control Relay #1 = Compr#1 C1 Starter Compressor OFF Compressor ON 5 Motor Control Relay #3 = Compr#3 C1 Starter Compressor OFF Compressor ON

Condenser Fan #3– Water Cooled

=N /Tower Fan #2-Water Cooled=Y 7 Li qui d Li ne #1 C1 Solenoid Cooling OFF Cooling ON

Condenser Fan #2 – Water Cooled

=N /Tower Fan #1-Water Cooled=Y 9 Motor Control Relay #2 = Compr#2 C2 Starter Compressor OFF Compressor ON

10 Motor Control Relay #4 = Compr#4 C2 Starter Compress or OFF Compressor ON 11 Condenser Fan #4 C2 Fan Contactor Fan OFF Fan ON 12 Liquid Line #2 C2 Solenoid Cooling OFF Cooling ON 13 Condenser Fan #5 C1 Fan Contactor Fan OFF Fan ON 14 Hot Gas Bypass #1 C1 Solenoid Cooling OFF Cooling ON 15 Hot Gas Bypass #2 C2 Solenoid Cooling OFF Cooling ON 16 Condenser Fan #6 C2 Fan Contactor Fan OFF Fan ON 17 Condenser Fan #7 C1 Fan Contactor Fan OFF Fan ON 18 Condenser Fan #8 C2 Fan Contactor Fan OFF Fan ON

C1,C2,

C1 /

C2 /

Alarm Indicator Alarm OFF Alarm ON

Fan Contactor/ Pump Contactor

Fan Contactor Fan OFF Fan ON

Fan OFF Fan ON

20 WGZ 030A through 120A OM WGZ-2

Setpoints

The following parameters are remembered during power off, are factory set to the Default value, and can be adjusted to any value in the Range column.

The PW (password) column indicates the password level that must be active in order to change the setpoint. Passwords are as follows:

O = Operator [0100] M = Manager [2001]

Table 8, Setpoints

Description Default Range PW

Unit Enable OFF OFF, ON O Unit Mode COOL COOL, COOL w/Glycol, ICE w/Glycol O Control source DIGITAL INPUT KEYPAD, B A S , DIGITAL INPUT O

Available Modes COOL COOL, COOL w/Glycol, /ICE w/Glycol M XXX Display Units XXX Language ENGLISH ENGLISH, (TBD) O BAS Protocol NONE NONE, BACnet, LonWorks, Modbus M Ident Number 001 001-999 M Baud Rate 9600 1200, 2400, 4800, 9600, 19200 M Evap LWT (COOL & GLYCOL) Ice LWT (ICE ) Evap Delta T Startup Delta T Stop Delta T Max Pulldown Rate Low Ambient Lockout (Water-cooled = No) Demand Limit Off Off, On M * Water Cooled N N,Y M * Refrigerant Select None R22, R407c -* Phase Voltage Protect i on N N,Y M * Ground Fault Protection N N,Y M * Set at Factory Speedtrol Option N N,Y M

Staging

Stage Up Delay 240 90 to 480 sec M Stage Down Delay 30 20 to 60 sec M

Timers

Evap Recirculate Timer 30 sec 15 to 300 sec M Cond Pump Recirculate Timer (Water-cool ) 30 sec 15 to 90 sec M Low Evap Pressure Delay 30 sec 15 sec to 30sec M LowOATTmr 60 sec 30 to 240 sec Ice Time Delay 12 hrs 1-23 Hrs M Clear Ice Timer No No, Yes M Hot Gas Bypass Solenoid Val ve Del ay 30 sec 30 to 180 sec M Start-Start 15 min 10 to 60 min M Stop-Start 5 min 3 to 20 mi n M

Alarms

Evaporator Freeze Condenser Freeze Low Evap Pressure 58 psi 30 to 60 psi M Evap Flow Proof 3 sec 1 to 10 sec M High Condenser Pressure 380 psi 380 to 390 psi M

Events

Low Evap Pressure-Hold R22 59 psi 24 to 65 psi M Low Evap Pressure-Hold R407c 52 psi 20 to 65 psi M Low Evap Pressure-Unload R22 58 psi 24 to 65 psi M Low Evap Pressure-Unload R407c 50 psi 20 to 65 psi M High Condenser Stage Down 370 psi 365 to 375 psi M

Condenser Fans (Water Cooled = N)

Fans Per Circuit 2 2 to 4 M Speedtrol; Option N N, Y M C1/ C2 – Stage #1 / #2 On (OAT < 70°F) C1/ C2 – Stage #3 / #4 On 290 psi 220 to 330 psi M

°F/psi °F/psi, °C/kPa

44. 0°F 20.0 to 60.0 °F

40. 0°F 20.0 to 40.0 °F

10. 0°F 6.0 to 16.0 °F

2.0°F 1.0 to 10.0 °F

0.5°F 0 to 3.0°F

1.0°F 0.5 to 5.0°F

35.0°F -2(35) to 70°F

36.0 °F 18 to 42 °F

34.0 °F 18 to 42 °F

200 psi 140 to 200 psi M

Continued next page

O O O O O M M

M M

OM WGZ-2 WGZ 030A through 120A 21

Description Default Range PW

C1/ C2 – Stage #5 / #6 On 300 psi 220 to 330 psi M C1/ C2 – Stage #7/ #8 On 310 psi 220 to 330 psi M C1/ C2 – Stage #3/ #4 Off 180 psi 150 to 220 psi M C1/ C2 – Stage #5/ #6 Off 190 psi 150 to 220 psi M C1/ C2 – Stage #7/ #8 Off 200 psi 150 to 220 psi M

Cooling Tower (Water Cooled = Y)

Tower Control None None, Temperature M Tower Stages 2 0 to 2 M Stage Up Time 2 min 1 t o 60 min M Stage Down Time 5 min 1 to 60 min M Stage Differential Stage #1 On Stage #2 On

Cooling Tower (Water Cooled = Y) Valve / VFD

Valve/VFD Control None Valve Setpoint

Valve Deadband Stage Fan Down @ 20% 0 t o 100% M Stage Fan Up @ 80% 0 to 100% M Valve Control Range (Min) 10% 0 to 100% M Valve Control Range(Max) 90% 0 to 100% M

Valve Type NC (To Tower) Minimum Start P osition 0% 0 to 100% M

Minimum Position @ Maximum Start Posit i on 100% 0 to 100% M Maximum Position @ Error Gain 25 10 to 99 M Slope Gain 25 10 to 99 M

3.0 °F 1.0 to 10.0 °F 70 °F 40 to 120 °F 75 °F 40 to 120 °F

None, Valve Setpoint, Valve S tage, VFD Stage, Valve SP/VFD Stage

65 °F 60 to 120 °F

2.0 °F 1.0 to 10.0 °F

Normally Closed (NC), Normal l y Open (NO)

60 °F 0 to 100 °F

90 °F 0 to 100 °F

M M M

M M

Protection (Shutdown) Alarms

Equipment protection alarms trigger a rapid compressor shutdown. The following table identifies each equipment protection alarm, gives the condition that causes the alarm to occur, and states the action taken because of the alarm. Most equipment protection alarms require a manual reset. These alarms will energize a remote alarm if the unit is so wired in the field.

Table 9, Equipment Protection Alarms

NOTE: SP = Setpoint NOTE : UT = Rapid Stop for the entire unit (Both Circuit s), CT = Rapid St op for that circ uit only

Description Occurs When:

No Evaporator Water Flow

No Condenser Water Flow

Low Evaporator Pressure

High Condenser Pressure Mechanical High Pressure

Motor Protection Phase Voltage

Protection (optional) Ground Fault Protection (optional)

Evap Pump State = RUN AND Evap Flow Digital Input = No Flow & High Condenser Pressure for > Evap Flow Proof SP] Cond Flow Digital Input = No Flow for > Evap Flow Proof] Note: Water Cooled = Y Onl y Evaporator Press < Low Evap Pressure SP start Low Evap Pressure Time Delay – if af ter Time Delay if Evap Press > SP continue else stop Condenser Press & Condenser Flow > High Condenser Pressure SP For C1, Motor Start #1 On & Digital I nput = High Pressure For C2, Motor Start #2 On & Digital I nput = High Pressure Digital Input = High Motor Temperat ure On Power Up – Delay 150 Sec. Before check i ng If Phase Voltage Protec tion = Y, Then Digital Input = Phase/V ol t age Problem If Ground Fault Protection = Y, Then Digital Input = Ground Fault Protec tion Problem

Continued on next page.

Action

Taken

Rapid Stop UT

Rapid Stop CT

Rapid Stop CT Rapid Stop CT Rapid Stop CT Rapid Stop CT Rapid Stop CT

Reset

Manual

Manual Manual Manual

Manual

22 WGZ 030A through 120A OM WGZ-2

Description Occurs When:

Re-Start Fault Re-Start = Third Time Evap. Freeze Protect Evap LWT < Evaporator Freeze SP

Leaving Evap. Water Temp. Sensor Fault Evaporator Pressure Sensor Fault Condenser Pressure Sensor Fault Condenser Entering or Outside Ambient Temp. Sensor Fault

Sensor shorted or open Sensor shorted or open Sensor shorted or open

Sensor is open or shorted

Action

Taken

Rapid Stop UT Rapid Stop CT Rapid Stop UT Rapid Stop CT Rapid Stop CT

Rapid Stop UT

Reset

Manual Manual Manual Manual Manual

Manual

Event (Limit) Alarms

The following alarms do not cause a rapid shutdown but limit operation of the chiller in some way as described in the Action Taken column. These alarms do not trigger a remote alarm signal. They do appear in the Active Alarm menu, are logged, and light the Alarm LED. A password must be active to view these events in the Event Log.

Table 10, Limit Alarms

NOTE: SP = Setpoint NOTE: UT = Rapid Stop for the entire unit (Both Circuit s), CT = Rapid St op for that circ uit only

Description Occurs When: Action Taken Reset

Condenser Pressure High – Unload

Low Ambient Lockout

Evaporator Pressure Low – Hold

Evaporator Pressure Low – Unload

Condenser Freeze Protect

Pressure > High Condenser Stage Down setpoint

Outside Ambient < Low Ambient Lockout S P Note: Water Cooled = N Onl y Pressure < Low Evap Pressure–Hold setpoint

Pressure < Low Evap Pressure–Unload setpoint

Cond Sat Refr Temp < Condenser Freeze SP AND Cond Pump State = OFF Note: Water Cooled = Y Onl y

Stage off lag compressor on the circuit

Stage down & Shutoff Inhibit staging on lag

compressor on the ci rcuit Stage off lag compressor

on the circuit

Start condenser pump

Note, See Table 11 for low pressure hold and unload setpoints.

Condenser Press drops below (SP – 100psi) Outside Ambient > Low Amb Lockout (SP + 5ºF) Evap Press rises above (SP + 8psi) Evap Press rises above (SP + 10 psi + Stage Up Delta T)

Cond Sat Refr Temp > (Condenser Freeze SP + 2°F)

Table 11, Ref ri gerant Sensitive Set Point Defaults and Adjustment Range

R22 Refrigerant R407c Refrigerant

Set Point Name

Low Evaporator

Pressure Hold Loading

Low Evaporator

Pressure Unload

Default

(psi)

59.0

58.0

Adjustment Range

(psi)

24.0 – 65.0 (with glycol)

55.0 – 65.0 (w/o glycol)

24.0 – 65.0 (with glycol)

55.0 – 65.0 (w/o glycol)

Default

(psi)

52.0

50.0

Adjustment Range

(psi)

20.0 – 75.0 (with glycol)

58.0 – 75.0 (w/o glycol)

20.0 – 75.0 (with glycol)

58.0 – 75.0 (w/o glycol)

Unit Enable

• Enabling and disabling the chiller is controlled by the Unit Enable Setpoint with

options of OFF and ON. This setpoint can be altered by the keypad, BAS, Unit OFF input, and Remote input. The Control Source Setpoint determines which sources can change the Unit Enable Setpoint with options of SWITCHES, KEYPAD or NETWORK.

Changing the Unit Enable Setpoint can be accomplished according to the following table.

OM WGZ-2 WGZ 030A through 120A 23

Table 12, Unit Enable Combinations

NOTE: An “x” indicates that the val ue is ignored.

Unit Off

Input

Control Source

Setpoint

Remote

Input

Keypad

Entry

BAS

Request

Unit

Enable

OFF x x x x OFF

x SWITCHES OFF x x OFF ON SWITCHES ON x x ON ON KEYPAD x OFF x OFF ON KEYPAD x ON x ON ON NETWORK x x OFF OFF ON NETWORK OFF x x OFF ON NETWORK ON x ON ON

Unit Mode Selection

The overall operating mode of the chiller is set by the Unit Mode Setpoint with options of COOL, COOL w/Glycol, ICE w/Glycol, and TEST. This setpoint can be altered by the keypad, BAS, and Mode input. Changes to the Unit Mode Setpoint are controlled by two additional setpoints.

Available Modes Setpoint: Determines the operational modes available at any time with options of COOL, COOL w/Glycol, COOL/ICE w/Glycol, and TEST.

Control Source Setpoint: Determines the source that can change the Unit Mode Setpoint with options of KEYPAD, NETWORK, or SWITCHES.

Table 13, Unit Mode Combinations

Changing the Unit Mode Setpoint can be accomplished according to the following table. NOTE: An “x” indicates that the value is ignored.

Control

Source

Setpoint

x x x x COOL COOL

x x x x COOL w/Glycol COOL w/Glycol SWITCHES OFF x x COOL/ICE w/Glycol COOL w/Glycol SWITCHES ON x x COOL/ICE w/Glycol ICE w/Glycol

KEYPAD x COOL w/Glycol x COOL/ICE w/Glycol COOL w/Glyco l

KEYPAD x ICE w/Glycol x COOL/ICE w/Glycol ICE w/Glycol NETWORK x x COOL COOL/ICE w/Glycol COOL w/Glycol NETWORK x x ICE COOL/ICE w/Glycol ICE w/Glycol

x x x x TEST TEST

Mode

Input

Keyp ad Entry

BAS

Request

Available Modes

Setpoint

Unit Mode

Low Ambient Start (Remote Condenser Only)

If Water Cooled = Y, then this function is not applicable. If SpeedTrol = N, this step is bypassed and unit starts in the normal operation. If the

SpeedTrol = Y then unit starts per table below. This step will bypass the “Low Evaporator Pressure” alarm until Low Ambient Start is completed.

When there is a call for Cooling the following steps are used.

24 WGZ 030A through 120A OM WGZ-2

Table 14, Low Ambient Start Sequence

NOTE: CT = Rapid Stop for that circuit only

Descriptio n

Check #1

Check #2

Check #3

Check #4

Occurs When: Action Taken

After 15 Seconds after starting first compressor, If the Evap Press is < 0.48 times the Low Evap Pressure SP take action, else continue After 15 Seconds after Check #1, If the Evap Press is < 0.66 times the Low Evap Pressure SP take action, else continue (30 Sec Total) After 15 Seconds after Check #2, If the Evap Press is < 0.83 times the Low Evap Pressure SP take action, else continue (45 Sec Total) After 15 Seconds after Check #3, If the Evap Press is < Low Evap Pressure SP take action, else continue in normal operation (60 Sec Total)

Rapid Stop – See Low Ambient ReStart below

Rapid Stop – See Low Ambient ReStart below Rapid Stop – See Low Ambient ReStart below

Rapid Stop – See Low Ambient ReStart below

Low Ambient Re-Start

If the Evap Pressure fails during the low ambient start, the controller waits until the anticycle timers expire then tries to re-start. It will attempt a start 3 times, and reset the counter if unit continues in normal operation. If it fails on the third attempt, it will initiate the Low Ambient Re-Start Alarm Fault (Manual Reset).

Automatic A dj usted Limits

The following are setpoints that will be changed are based on the option selected.

Evaporator Leaving Water Temperature

Mode Range

Unit Mode = Cool Unit Mode = Glycol, Ice

40 to 60°F 20 to 60°F

Evaporator Freeze Temperature

Mode Range

Unit Mode = Cool Unit Mode = Glycol, Ice

36 to 42°F 18 to 42°F

Low Evaporator Pressure

Mode Range

Unit Mode = Cool 55 to 65 Psig Unit Mode = Glycol, Ice 30 to 65 Psig

Low Evaporator Pressure Hold and Unload

Mode Range

Unit Mode = Cool 55 to 65 Psig Unit Mode = Glycol, Ice 31 to 65 Psig

Low Ambient Lockout Temperature

SpeedTrol Range

SpeedTrol = N SpeedTrol = Y

OM WGZ-2 WGZ 030A through 120A 25

35 – 60°F

-2 – 60°F

Staging Parameters

Lockouts

There are conditions that shall prevent a start when the unit status is AUTO.

Low Ambient Lockout

If the unit status is AUTO, but no compressors have started, and the outside ambient temperature drops below the low ambient lockout setpoint, the unit will transition to the Low Ambient Lockout state. This condition will not trigger an alarm. The condition will be indicated by showing the unit status as “Low Amb Lockout”. The chilled water pump will shut off. If lockout occurs while the unit is running, the compressors will pump down.

Compressor start will be delayed until the outside ambient temperature rises to the setpoint plus 5 degrees F.

Wait For Evap or Cond Water Flow

If the unit status is AUTO and the evap pump status is START, then the unit will wait for the evaporator and condenser flow switches to close. During this time, the condition will be indicated by showing the unit status as “Wait For Flow”. The water flow loss logic will allow the Loss of Flow alarms to be automatically reset two times in any 24 hour period.

• If either water flow is lost any time a compressor is running the chiller will shutdown all of the running compressors and each Cirucit’s status will become Off:Ready.

• The Unit status will become Auto:Wait For Flow and the Evaporator or CondenserWater Pump status will change to Start. The Unit’s alarm output will be turned On and the red LED behind the upper left key of the control will turn On.

• When the flow returns without interruption for the Evaporator Flow Recirculation Time (30 seconds is the default time) the unit is allowed to start as the cycle and staging timers are cleared.

• The alarm output and red LED will be turned off and normal start and staging logic is allowed to proceed.

• If water flow is lost a second time with in 24 hours the procedure described above is repeated.

• A third occurrence of evaporator flow loss in 24 hours triggers the standard Evaporator or Condenser Water Flow Loss alarm. All circuits with running compressors shutdown and the Unit status becomes Off:Alarm.

• The standard Evaporator or Condenser Water Flow Loss alarm must be manually cleared before the unit is allowed to restart.

• The twenty four hour timer that limits the auto restarts is reset when the control’s clock rolls over to 00:00 each night

Capacity Overrides

The following conditions override the capacity control mode when the chiller is in the cool or ice mode. The purpose of the overrides is to keep the unit online (although at reduced capacity) during certain abnormal operating condition. If and when the “off” condition returns to normal, the override is eliminated and the unit returns to normal operation based on the capacity control.

Low Evaporator Pressure

If the evaporator pressure drops below the Low Evaporator Pressure Hold setpoint and only one compressor on that circuit is running, the second compressor is prevented from starting.

If the evaporator pressure drops below the Low Evaporator Pressure Unload setpoint, and both compressors on the circuit are running, the “first off” compressor on that circuit is shut off.

26 WGZ 030A through 120A OM WGZ-2

Maximum LWT Rate

The maximum rate at which the leaving water temperature can drop is limited at all times by the Maximum Rate setpoint (2°F/minute). If the rate exceeds this setpoint, no more compressors will be started until the pulldown rate is less than 2°F/minute.

High Condenser Pressure

If the discharge pressure rises above the High Condenser Pressure Unload setpoint, and both compressors on the circuit are running, the “first off” compressor on the circuit is shut off.

Digital Output Control

Each digital output is be controlled according to the following rules. All outputs are initialized to OFF at power on.

Alarm – (Terminals J12 – NO1)

This output is turned ON when any Equipment Protection ALARM occurs. It is turned OFF when all alarms have been cleared.

Evaporator Pump – (Terminals J12 – NO2)

An Evaporator Water Pump output is ON if the Evap State is set to START or RUN.

Hot Gas Bypass Solenoid – (Terminals J21 – NO14, J21 – NO15)

This output shall be ON when the Lead Compressor per Circuit is the only compressor ON, except during Pumpdown.

This output shall be ON when the Compressors are ON. It shall be OFF for all other cases.

Digital Output Control

Each digital output is controlled according to the following rules. All outputs are initialized to OFF at power on.

Fan #1 to #8 (Air-Cooled Condensers)

[Water Cooled = N] – Condenser Fans Staging is based on condenser pressure as selected by Fan Stage On & Off setpoints. Fans 1, 3, 5 and 7 are for circuit 1, and fans 2, 4, 6, and 8 are for circuit 2. Fans 1 and 2 start with the first compressor on the respective circuit when the ambient temperature is greater than 75°F. Below 75°F, these fans start when the condenser pressure gets up to the stage on setpoint.

Condenser Pump and Tower Fans (Water-Cooled Condenser)

[Water Cooled = Y] – Condenser Pump is on with first Compressor on. Tower fan control is active when the Tower Control setpoint is set to Temperature and the condenser pump is in the RUN state. Staging is based on Entering Condenser Water Temperature (ECWT). Operation depends on the following parameters.

• Condenser pump state

• ECWT

• Stage up and stage down timer values

• Tower setpoints (Tower Control, Tower Stages, Stage Up Time, Stage Down Time,

Stage Differential, Stage #1 ON, Stage #2 ON, Stage Down @, Stage Up @)

OM WGZ-2 WGZ 030A through 120A 27

When the condenser pump starts, the stage-up timer starts. The first stage turns ON when the following conditions are met:

• The stage-up timer completes

• The ECWT is > Stage #1 ON setpoint

• Bypass valve position is > the Stage Up @ setpoint (only if Valve/VFD Control setpoint

= Valve Stage)

Additional stages turn on (up to the number specified by the Tower Stages setpoint) when above conditions are met for the next stage plus the following condition:

• VFD Speed is > the Stage Up @ setpoint (only if Valve/VFD Control setpoint = VFD Stage OR Valve SP/VFD Stage)

Down staging occur when the following conditions are met:

• The stage-down timer completes

• The ECWT is < Stage #X ON (Temp) setpoint – Stage Differential (Temp) setpoint

• Bypass valve position is < the Stage Down @ setpoint (only if Valve/VFD Control

setpoint = Valve Stage)

• VFD Speed is < the Stage Down @ setpoint (only if Valve/VFD Control setpoint = VFD Stage OR Valve SP/VFD Stage)

Each stage-up or stage-down event restarts both the stage-up and-stage down timers. Only one fan output is switched at a time (except that all outputs switch OFF when the condenser pump state equals OFF).

Analog Output Control

Each analog output is controlled according to the following rules/algorithms and in accordance with whether the Compressor Mode setpoint is set to AUTO or MANUAL (normal operation). All outputs shall be initialized to 0 at power on.

Cooling Tower Bypass Valve

When the Valve/VFD Control setpoint is set to None or VFD Stage, this output is set to 0. Otherwise, it is controlled as described below.

Initial Valve Position

When the condenser pump is not in the RUN state, the valve output is set as a function of entering condenser water temperature (ECWT) per the following graph.

28 WGZ 030A through 120A OM WGZ-2

Max Position @

Setpoint

(90°F)

Min Position @

Setpoint

(60°F)

Initial Valve Position

(values are examples only)

Min Start Position

Setpoint

(10%)

Max Start Position

Setpoint

(90%)

Operation Af ter Start

When the condenser pump is in the RUN state, the valve output is controlled in one of two modes as specified by the Valve/VFD Control setpoint. The controlled parameter is the condenser entering water temperature. When the desired output signal varies from 0 to 100%, the output voltage will vary as shown below.

• 0 to 10 VDC (Valve Type = NC)

• 10 to 0 VDC (Valve Type = NO)

Valve Setpoint Mode

This mode is operational when the Valve/VFD Control setpoint is set to Valve Setpoint or Valve SP/VFD Stage. In this mode the valve output is varied with a proportional-derivative (PD) algorithm (with deadband) in order to maintain the controlled parameter (CP) at the desired value. The output is always limited between the Valve Control Range (Min) setpoint and the Valve Control Range (Max) setpoint. A valve increment is computed once every 5 seconds according to the following equation.

• Increment = [(Error) * (Error Gain setpoint)] + [(Slope) * (Slope Gain setpoint)] Where: Error = ECWT – Valve Setpoint Slope = (Present CP) – (Previous CP)

When the Error is > the Valve Deadband setpoint, the valve position analog output (% of full scale) is updated according to the following equation.

• New %Position = Old %Position + Increment/10.

Valve Stage Mode

This mode is only operational when the Valve/VFD Control setpoint is set to Valve Stage. In this mode the valve output is controlled as for Valve Setpoint mode (above) except that the active setpoint for the controlled parameter is selected according to the following table.

# Of Fans ON Active Setpoint

0 Valve Setpoint 1 Stage #1 ON 2 Stage #2 ON 3 Stage #3 ON 4 Stage #4 ON

OM WGZ-2 WGZ 030A through 120A 29

Cooling Tower Fan VFD

When the Valve/VFD Control setpoint is set to None, Valve Setpoint, or Valve Stage, this output is set to 0. Otherwise, it is controlled in a manner identical to Valve Stage Mode (above) except that (1) it is kept at zero until the first fan stage is ON and (2) the following setpoints do not apply.

• Valve Control Range (Min)

• Valve Control Range (Max)

• Valve Type

Evaporator Water Pump State Control

Operation of the evaporator pump is controlled by the state-transition diagram shown below. A state variable (Evap State) is used to maintain the current state (OFF, START, or RUN). The fixed 30 second timer will start when flow is first indicated by the Evaporator Water Flow Switch digital input. This timer is considered expired after 30 seconds.

TEST:

freeze) OR Circuit alarm on both circuits OR Unit enab le = off OR Circuit PumpDn Switch = off for all circuits (and pumpdn completed)

Power ON

Unit alarm (except evap

OFF

Unit Enable = On

TEST:

AND at least one circuit is enabled an d no t in alarm state OR Evap Freeze Protection

Unit alarm (except evap

TEST:

freeze) OR Circuit alarm on both circuits OR Unit enable = off OR Circuit PumpDn Switch = off for all circuits (and pumpdn completed)

RUN

Flow OK for

TEST:

30 Seconds

START

Condenser Water Pump State Control

Operation of the Condenser pump is controlled by the state-transition diagram shown below. A state variable (Cond State) is used to maintain the current state (OFF, START, or RUN).

Condenser Pump State Diagram

Cond Flow Alarm OR Unit State = Off OR Evap Pump State = Start OR No Circuit Available OR LWT error < Start Delta] AND No Cond Refrig Freeze Event AND No Compressor Running

Run Start

Off

Cond Flow Alarm OR [Unit State = Off OR No Circuit Available OR Evap Pump State = Start OR LWT error < Start Delta] AND No Cond Refrig Freeze Event AND No Compressor Running

[Cond Pump State = Start AND Flow Switch Closed] for time > Cond Pmp Recirc Time seconds

Unit State=Auto AND Any Circuit Available AND Stage up now = True] OR Cond Refrig Freeze Event AND No Cond Flow Alarm

30 WGZ 030A through 120A OM WGZ-2

Condenser Pump Control

The Condenser Flow Recirculation Time Set Point is found on the Unit Set Points Screen Five, line four. The default value is 30 seconds and the set point is adjustable from 15 seconds to 90 seconds.

The condenser water pump starts if the control has detected sufficient load after the evaporator water pump has started and evaporator water flow has been established.

The condenser water pump is enabled in the “Start” mode. It will remain in the “Start” mode until condenser water flow has been established. If continuous flow has been established for Condenser Flow Recirculation Time the condenser water pump mode becomes “Run” and the first compressor is enabled.

If no flow is detected while the condenser water pump is in the “Start” mode, the logic described on page 26 will be in effect

Inconsistent condenser water flow will hold the condenser water pump in the “Start” mode until constant flow has been established for Condenser Flow Recirculation Time seconds.

When the condenser water pump is in “Run” mode, if condenser water loop flow is lost for three seconds a “No Condenser Water Flow” alarm is generated.

The condenser water pump mode is displayed on the Unit Status Screen One, line four. It is combined with the evaporator pump mode and the line states “Ev/Cnd Pmp Off/Off” when both pumps are off. The text before the second ‘/’ is the evaporator water pump mode and the text after the second ‘/’ is the condenser water pump mode.

The condenser water pump mode and the Condenser Flow Recirculation Time set point are not displayed when the unit is configured for a remote condenser (Water Cooled =Off).

The condenser water pump logic will shutdown the condenser water pump when the evaporator pump state has been changed to Start. When the evaporator pump is in the Start state the Unit is waiting for evaporator water flow to be confirmed and no compressors will start. It is not necessary to run the condenser pump while waiting for evaporator flow to be confirmed.

Using the Controller

Getting Started

There are two basic procedures to learn in order to utilize the MicroTech II controller:

1. Navigating through the menu matrix to reach a desired menu screen and knowing where a particular screen is located.

2. Knowing what is contained in a menu screen and how to read that information or how to change a setpoint contained in the menu screen.

D.. Navigating Through the Menus

The menus are arranged in a matrix of screens across a top horizontal row. Some of these top-level screens have sub-screens located under them. The general content of each screen and its location in the matrix are shown in Figure 11. (A detailed description of each menu begins on page 34.) There are two ways to navigate through the menu matrix to reach a desired menu screen.

One is to scroll through the matrix from one screen to another using the four ARROW keys.

OM WGZ-2 WGZ 030A through 120A 31

The other way is to use shortcuts to work through the matrix hierarchy. From any menu screen, pressing the MENU key will take you to the top level of the hierarchy. The display will show ALARM, VIEW, and SET as shown in Figure 9. This corresponds to the second row of screens on Figure 11. One of these groups of screens can then be selected by pressing the key connected to it via the pathway shown in Figure 9 on page 19.

For example, selecting ALARM will go the next row of menus under ALARM (ALARM LOG or ACTIVE ALARM). Selecting VIEW will go the next level of screens under VIEW (VIEW UNIT STATUS or VIEW UNIT TEMP). Selecting SET will go to a series of screens for looking at and changing setpoints.

After pressing the MENU button, the top-level menu screen will show:

< ALARM < VIEW < SET <

After pressing the “VIEW” menu button, a menu screen will show:

VIEW < COMPRESSOR

< UNIT < EVAPORATOR < FANS

After pressing the “EVAPORATOR” menu button, the selected data screen will show:

VIEW EVAP

(screen data) (screen data) (screen data)

The arrow keys will automatically return to the “scroll” mode at this time.

MENU Key

The MENU key is used to switch between the shortcut method (known as the MENU mode and as shown in Figure 9) and scrolling method (known as the SCROLL mode). The MENU mode is the shortcut to specific groups of menus used for checking ALARMS, for VIEWING information, or to SET setpoint values. The SCROLL mode allows the user to move about the matrix (from one menu to another, one at a time) by using the four ARROW keys. A typical menu screen is shown in the following figure. Pressing the MENU key from any menu screen will automatically return you to the MENU mode.

32 WGZ 030A through 120A OM WGZ-2

Figure 10, Display in the Shortcut ( SCRO LL) M ode and Keypad Layout

Air Conditi oning

MENU Key

VIEW UNIT STATUS Unit = COOL Compr. #1/#2=OFF/ OFF Evap Pump = RUN

ARROW

ENTER Key

Pressing the ENTER key changes the function of the ARROW keys to the editing function as shown below:

LEFT key Default RIGHT key Cancel

, changes a value to the factory-set default value.

, cancels any change made to a value and returns to the original setting. UP key Increment DOWN key Decrement

, increases the value of the setting

decreases the value of a setting. These four edit functions are indicated by one-character abbreviation on the right side of the display (this mode is entered by pressing the ENTER key).

Most menus containing setpoint values have several different setpoints shown on one menu. When in a setpoint menu, the ENTER key is used to proceed from the top line to the second line and on downward. The cursor will blink at the entry point for making a change. The ARROW keys (now in the edit mode) are used to change the setpoint as described above. When the change has been made, press the ENTER key to enter it. Nothing is changed until the ENTER key is pressed.

For example, to change the chilled water setpoint:

1. Press MENU key to go to the MENU mode.

2. Press SET (the UP Key) to go to the setpoint menus.

3. Press UNIT SPs (the Right key) to go to setpoints associated with unit operation.

4. Press the DOWN key to scroll down through the setpoint menus to the third menu

which contains Evap LWT=XX.X°F.

5. Press the ENTER key to move the cursor down from the top line to the second line in

order to make the change.

6. Use the ARROW keys (now in the edit mode as shown above) to change the setting.

7. When the desired value is achieved, press ENTER to enter it and also move the cursor

down.

At this point, the following actions can be taken:

1. Change another setpoint in this menu by scrolling to it with the ENTER key.

2. Using the ENTER key, scroll to the first line in the menu. From there the ARROW

keys can be used to scroll to different menus.

OM WGZ-2 WGZ 030A through 120A 33

Menu Screens

Various menus are shown in the controller display. Each menu screen shows specific information, in some cases menus are only to view status of the unit, in some cases for checking alarms, and in some cases they are used to set setpoint values that can be changed.

The menus are arranged in a matrix of screens across a top horizontal row. Some of these top-level screens have sub-screens located under them. The content of each screen and its location in the matrix are shown in Figure 11. A description of each menu begins on page

34. The arrow keys on the controller are used to navigate through the menus. The keys are also

used to change numerical setpoint values contained in certain menus.

Figure 11, Menu Matrix

“MENU”

“VIEW” MENUS

UNIT CIRCUITS REFRIGERANT FANS

VIEW UNIT

STATUS

VIEW UNIT

STATUS

VIEW UNIT

TEMP

(1)

(5)

(1)

VIEW UNIT

TEMP

(2)

VIEW

CIRC #1

STATUS

(1)

VIEW COMP #1 STATUS

(3)

⇐ Continued ⇐

(Right side of matrix continued from above)m

“ALARM” MENUS “SET” MENUS

ALARM LOG

(LAST)

TYPE, TIME

ALARM LOG

(NEXT TO LAST)

ALARM LOG (SECOND TO

LAST)

ALARM LOG

LAST 25 SHOWN

ACTIVE ALARM ( 1)

TYPE, TIME

ACTIVE ALARM ( 2)

TYPE, TIME

ADDITIONAL

ACTIVE ALARM ( 3)

CLEAR/VIEW

SET UNIT SPs, (4)

VIEW

CIRC #2

STATUS

(1)

VIEW

CIRC #2

STATUS

(3)

SET UNIT SPs, (1) SET C O M P SPs

SET UNIT SPs, (2) SET C O M P SPs

SET UNIT SPs, (3) SET LIMIT ALARMS

(to 13)

VIEW

REFRIGERANT

CIRCUIT #1

(1)

VIEW EVAP

(2)

(1)

(2)

SET TO WER

VIEW

REFRIGERANT

CIRCUIT #2

(1)

VIEW EVAP

(2)

SET LIMIT ALARMS

VIEW FAN/TOWER

(1)

(2)

(3)

(1)

(n)

SET FANS (1)

STAGES

FANTROL

SET FANS (2)

STAGE ON

SET FANS (3)

STAGE O FF

SET

TOWER (1)

SET

TOWER (2)

SET

TOWER (3)

(to n)

Selection can be made within the matrix by using t he LE FT/ RIGHT keys t o move be twee n columns and the UP/DOWN keys to move between rows.

Menu Descriptions

This section contains information on each screen. The menu screens are in order of the matrix in Figure 11 going from left to right and down when there are sub-menus. Many menus are self-explanatory. A Setpoint menu allows selection of whether the unit has a water-cooled condenser, WaterCooled = Y (Yes) or a remote condenser, WaterCooled = N (No). This selection will alter some menus as appropriate to the type of condenser.

34 WGZ 030A through 120A OM WGZ-2

Screen Definitions – ME NU Top level menu:

< ALARM < VIEW < SET <

ALARM menu:

ALARM < ACTIVE

< LOG < <

VIEW menu:

VIEW < COMPRESSOR

< UNIT < EVAPORATOR < FANS/TOWER

VIEW UNIT menu:

VIEW < TEMP UNIT < STATUS

< REFRIGERANT

SET menu:

SET < ALARM LIMITS

< UNIT SPs < COMPRESSOR SPs < FANS/TOWER SPs

Screen Definitions – VIEW View Unit Status

VIEW UNIT STATUS (1) Auto Cooling Stage = 0 Evap Pump = RUN

Unit states can be OFF, COOL, GYLCOL, ICE, or ALARM as determined from the Unit Mode setpoint, the Unit Enable, and the presence of an alarm.

Circuit states can be OFF/OFF, ON/OFF, OFF/ON, and ON/ON. Evaporator Pump States can be OFF, STRT, or RUN. When more than one screen are stacked (i.e., relate to each other on the same subject), they

are numbered sequentially with the numbers appearing in the upper-right corner.

VIEW UNIT STATUS (2) Demand Limit=Stg 4 Network Limit=Stg 4

OM WGZ-2 WGZ 030A through 120A 35

VIEW UNIT STATUS (3) Stg Up Delay=XXX sec Stg Dn Delay=XXX sec Ice Delay=XXh XXm

VIEW UNIT STATUS (4) D.O. 111111111 123456789012345678 000000000000000000

This menu gives the status of digital outputs (D.O.), 1=ON, 0=OFF. Numbers are 1 through

18. See Table 7 on page 20 for number reference.

VIEW UNIT STATUS (5) D.I. 111111111 123456789012345678 000000000000000000

This menu gives the status of digital inputs (D.I.), 1=ON, 0=OFF. Numbers are 1 through

18. See Table 6 on page 20 for number reference.

View Unit Tempertures

Water Cooled = Y Water Cooled = N

VIEW UNIT TEMP (1) VIEW UNIT TEMP (1) Evap LWT = XX.X°F Evap LWT = XX.X°F Cond EWT = XXX.X°F OAT = XXX.X°F LWT Target = XX.X°F LWT Target = XX.X°F

The difference between the two screens above is that water-cooled units will give the entering condenser water temperature and air-cooled units will give the outside air temperature (OAT). The outside-air temperature sensor is furnished with the unit, inside the control panel, wired to the correct terminals. It must be installed outdoors in a location that will give the true outdoor temperature that the condenser coils will see. Splicing of the sensor lead may be required. The unit will not operate without the sensor installed.

VIEW UNIT TEMP (2) LWT Pulldn= XX.X °F Control Band= XX.X°F

VIEW UNIT TEMP (3) Control Temps

Start Up XX.X°F Stage Up XX.X°F

VIEW UNIT TEMP (4) Control Temps

Start Down XX.X°F Stage Down XX.X°F

36 WGZ 030A through 120A OM WGZ-2

View Circuit

VIEW CIRCUIT#1 (1) OFF

VIEW CIRCUIT#1 (2) Comp 1 = OFF Hours = XXXXX Starts = XXXXX

VIEW CIRCUITt#1 (3) Comp 3 = OFF Hours = XXXXX Starts = XXXXX

VIEW CIRCUIT#2 (1) Off

VIEW CIRCUIT#2 (2) Comp 2 = OFF Hours = XXXXX Starts = XXXXX

VIEW CIRCUIT#2 (3) Comp 4 = OFF Hours = XXXXX Starts = XXXXX

View Refrigerant

VIEW REFRG Cir 1 (1) Evap Press XXX.X psi Cond Press XXX.X psi

R22 Refrigerant 407C Refrigerant

VIEW REFRG Cir 1 (2) Sat Evap XXX.X °F Sat Cond XXX.X °Fi

VIEW REFRG Cir 1 (2) Evap Dew XXX.X °F Cond Mid XXX.X °F

OM WGZ-2 WGZ 030A through 120A 37

Code has been created that converts R407c refrigerant pressures to saturated temperatures. R407c refrigerant is a blended refrigerant. To overcome the glide factor, the saturated temperatures are displayed as dew point temperatures for pressures below 120.0 psi. Saturated temperatures for refrigerant pressures greater than 120.0 psi are displayed as midpoint temperatures (a mid-point temperature is the average of the dew-point and bubblepoint temperatures for any pressure). As a result, the View Refrigerant Screen Two for each circuit shows “Evap Dew” temperature on line two and “Cond Mid” on line three when R407c refrigerant is selected.

Modified macroblocks convert R22 refrigerant pressure to saturated temperatures with the same resolution and accuracy as the R407c conversions. The control does not use saturated temperature for control purposes, but they are displayed on the control screen. Line two of the View Refrigerant Screen Two for each circuit still says “Sat Evap” and line three says “Sat Cond” when R22 refrigerant is selected.

VIEW REFRG Cir 1 (3) SuctionTemp=XXX.X°F Surperheat = XXX.X°F EvapApproach= XX.X°F

VIEW REFRG Cir 2 (1) Evap Press XXX.X psi Cond Press XXX.X psi

R22 Refrigerant 407c Refrigerant

VIEW REFRG Cir 2 (2) Sat Evap XXX.X °F Sat Cond XXX.X °Fi

VIEW REFRG Cir 2 (2) Evap Dew XXX.X °F Cond Mid XXX.X °F

VIEW REFRG Cir 2 (3) SuctionTemp=XXX.X°F Surperheat = XXX.X°F EvapApproach= XX.X°F

Water Cooled = Y Only

VIEW TOWER (1) Stages ON=1of2

EntCondTemp = XXX °F

Setpoint = XXX °F

The first Stages ON value is the number of fan stages ON. The second number is the Tower Stages setpoint (0 if Tower Control = None). This screen shows the number of tower fans “on” for each circuit. This screen will show the fans “on” whether they are actually connected to and controlled by the MicroTech II controller or not.

Water Cooled = Y Only

VIEW TOWER (2)

38 WGZ 030A through 120A OM WGZ-2

Bypass Valve = XXX% VFD Speed = XXX%

The Bypass Valve value shall be “None” (in place of XXX%) if the Valve/VFD Control setpoint = None or VFD Stage. The VFD Speed value shall be “None” if the Valve/VFD Control setpoint = None, Valve Setpoint, or Valve Stage.

Water Cooled = N Only

VIEW FANS Circuit#1 ON=1of4 Circuit#2 ON=1of4

This screen shows the number of air-cooled condenser fans “on” for each circuit. This screen will show the fans “on” whether they are actually connected to and controlled by the MicroTech II controller or not.

Screen Definitions – ALARM

ALARM ACTIVE (X) Alarm Description hh:mm:ss dd/mmm/yyyy

ALARM ACTIVE (X) No more alarms Press ENTER to clear all active alarms

If the unit is off on a shutdown alarm or running, but in a limit alarm condition, the cause and date will appear in the upper screen. If there is a simultaneous occurrence of more than one alarm, the others will appear in additional screens below the first one, accessed by the DOWN ARROW.

Either type alarm will light a red light in back of the LEFT-ARROW KEY. The light will go out when the fault is cleared. To clear the fault, scroll down to the last screen and press ENTER. If other faults have appeared, they will all be cleared at the same time. It is not necessary to have a password open to clear alarms.

ALARM LOG (1) Alarm Description hh:mm:ss dd/mmm/yyyy Data

The last 25 alarms, either shutdown or limit, are shown in this menu and subsequent menus located under it. ARROW DOWN from this menu will go to the next-to-last alarm, ARROW DOWN again will go to the second from last, and so on through the last 25 occurrences. The screens are numbered (1), (2), (3), etc.

Screen Definitions – SET Set Unit Setpoints

SET UNIT SPs (1) Unit Enable = OFF Unit Mode = COOL Source = KEYPAD

Unit Enable settings can be OFF and ON as determined from the Unit Enable setpoint.

OM WGZ-2 WGZ 030A through 120A 39

Unit Enable is an external signal or a keypad setting that keeps the unit off when the setting is OFF and allows it to run if there is a call for cooling when the setting is ON. The source for the signal is selected in the 4

1. KEYPAD, in which case the selection is made in line 2 and would be normally selected as ON. This is the normal setting when no external signals are controlling the unit.

2. SWITCHES, in which an external switch is wired across terminals #25 and #35. (See wiring diagram page 8 or 9.)

3. NETWORK, used with BAS signal, which is wired to the three communication ports. Unit Mode settings can be

1. COOL, normal setting used with chilled water air-condition applications.

2. COOL w/GLYCOL, used with low temperature, glycol applications. It allows a lower LWT setpoint to be used.

3. ICE w/GLYCOL, used with ice storage systems, allows changing from chilled glycol operation to lower temperature ICE operation. In ICE, the unit runs at full load until the ICE setpoint is reached, at which time the unit shuts off. A three-position switch wired to terminals #28 and #38 initiates the change from glycol cooling to making ice. (See wiring diagrams on page 8 or 9.)

Unit Mode settings can be COOL COOLw/Glycol, or ICEw/Glycol, as determined from the Unit Mode setpoint.

line and can be:

Source settings can be KEYPAD, SWITCHES, or NETWORK as determined from the Mode Source setpoint.

SET UNIT SPs (2) Available Modes

=COOL

Set w/Unit Switch Off

SET UNIT SPs (3) Evap LWT = XX.X°F Ice LWT = XX.X°F EvapDeltaT= XX.X°F

SET UNIT SPs (4) Start Delta= XX.X°F Stop Delta= XX.X°F

See page 14 for an explanation of compressor staging.

Water-cooled = No Water-cooled = Yes

SET UNIT SPs (5) Max Pulldn=x.x°F/min

Evap Recirc=XXX sec LowAmbLock=XX.X°F

SET UNIT SPs (5) Max Pulldn=x.x°F/min

Evap Recirc=XXX sec Cond Recirc=XXX sec

40 WGZ 030A through 120A OM WGZ-2

SET UNIT SPs (6) Demand Limit=Off Water cooled=Off

Water Cooled = On is the setting for units with on-board water-cooled condensers. WaterCooled = OFF is used for units with remote condensers, usually air-cooled.

SET UNIT SPs (7) Ice Time Delay=Xxsec Clear Ice Delay=No H.G. Delay = XX sec

H.G. Delay, hot gas bypass delay, keeps the hot gas solenoid valveclosed when the first compressor on a circuit starts. This delay allows sufficient condenser pressure to build up.

SET UNIT SPs (8)

CLOCK

dd/mmm/yyyy

hh:mm:ss

Initial Screen

SET UNIT SPs (9) Units = °F/psi

Lang = ENGLISH

Refrig = None

• Logic allows the user to change the Refrigerant Type when the manager level password is active. After loading the software initially, the setting is still accessible without entering a password because the setting defaults to none and a Refrigerant Type must be selected before the program can start running.

• The refrigerant select field will display “SELECT TYPE” when no refrigerant type has yet been selected.

• The software has also been changed to prevent the Unit running until a refrigerant type has been selected. Unit will be disabled even if the Unit and Circuit switches are in the ON position.

SET UNIT SPs (10) Protocol = NONE

Ident Number=001 Baud Rate=9600

BAS interface settings, available mid-2003.

SET UNIT SPs (11) Evap Press Sensor Cir 1 Cir 2 Offset

00.0 00.0 (psi)

The pressure offsets on menus 8 and 9 and the temperature offsets on menus 10, 11 and 12 correct the controller's display of the parameters. The sensors used in these units have a high degree of repeatability but may need correction (offset). An accurate pressure gauge or thermometer is used to determine the correct temperature or pressure. A positive or

OM WGZ-2 WGZ 030A through 120A 41

negative offset value is then entered to make the controller reading agree with the measured value.

SET UNIT SPs (12) Cond Press Sensor Cir 1 Cir 2 Offset

00.0 00.0 (psi)

SET UNIT SPs (13) Leaving Evaporator

Water Temp Sensor

Offset= 00.0

SET UNIT SPs (14) OAT/Cond Lvg Water

Temperature Sensor

Offset= 00.0

SET UNIT SPs (15) Suction Temp Sensor Cir 1 Cir 2 Offset

00.0 00.0 (

SET UNIT SPs (16) ENTER PASSWORD: XXXX

Active Password Level: None

Two four-digit passwords provide OPERATOR and MANAGER levels of access to changeable parameters. The passwords are preprogrammed into the controller. Either password must be entered using the ENTER PASSWORD (12) screen before a protected setting can be changed. The operator password is 0100. The manager level is 2001.

This screen can be accessed either through the SET OTHER menu or by simply pressing the ENTER key while on one of the SET screens. The controller will automatically go from the screen with the setting change to this screen. After the correct password has been entered, the controller will automatically return to the original set screen.

Once a password has been entered, it remains valid for 15 minutes after the last key-press.

Set Compressor Setpoints

SET COMP SPs k,(1) Clear Cycle Tmr=No Stop-Start =XXmin Start-Start =XXmin

This menu sets the anti-recycle timers. Stop-Start is the time required before starting a compressor after it has stopped. Start-Start is the time required before starting a compressor after the last time it has started. It is recommended that the default values of 5 minutes and 15 minutes not be changed. Clear Cycle Tmr overrides the anti-recycle timers and should only be used for service testing and not for normal unit operation.

SET COMP SPs (2) InterStgUp =XXXsec

42 WGZ 030A through 120A OM WGZ-2

InterStgDown= XXsec

InterStageUp is the time delay since the last stage change before a compressor can stage on, default is 120 sec.

InterStageDn is the time delay since the last stage change before a compressor can stage off normally (not by an alarm). Default is 30 sec. It is recommended that these settings not be changed.

SET COMP SPs (3) Comp 1 = Enable Comp 3 = Enable

SET COMP SPs (4) Comp 2 = Enable Comp 4 = Enable

Enable screens #3 and #4 require the manager password to change.

SET ALARM LIMITS

SET ALARM LMTS (1) Low EVAP Pressure

Hold=XXXpsi

Unload=XXXpsi

The Hold and Unload have the same default value of 59 psi. If two compressors are running, the LowEvPrUnld is in effect and the lag compressor will be shut off to unload the unit. If one compressor is running, the LowEvPrHold is in effect and the lag compressor is prevented from starting, thereby holding the unit capacity.

The last action to take place is the shutoff of all compressors running when the LowEvPrStop setting is reached (default is 58 psi). Reducing these time intervals will increase detrimental compressor cycling. It is recommended that these settings not be changed.

SET ALARM LMTS (2) High Cond Pressure

Unload= XX.X°F

Stop=XXXsec

Unload is a limit alarm that unloads the unit at 370 psi in an attempt to prevent total shutdown from the HighCondPr at 380 psi. The stage down is set at 370 psi. It is recommended that these settings not be changed.

Stop (the unit high-discharge-pressure shutdown) is a stop alarm that shuts off the unit when the discharge pressure reaches the setting. The default setting is 380 psi.

LowEvPrDelay is a time delay on the low pressure trip that reduces nuisance low-pressure trips. The default setting is 30 seconds.

SET ALARM LMTS (3) GroundFault = N PhaseVoltage = N Low OATStartTMR=XXsec

OM WGZ-2 WGZ 030A through 120A 43

GroundFault and PhaseVoltage entries are Y (Yes) or N (No) depending on whether the options are on the unit.

CondFreeze is an alarm that reduces the chance of freezing the water in the condenser (when compressors are not running). An alarm is registered and the condenser pump is energized at the same time. The alarm setpoint is 34°F saturated condenser temperature and it resets at +2°F above the setpoint.

SET ALARM LMTS (4) Evap Freeze = XX.X°F

EvapFlowProff=XXXsec

Evap Freeze (the unit freeze protection shutdown) is actually a stop alarm and shuts off the unit when the LWT reaches 36°F. It is cleared by going to the CLEAR ALARM menu in the ACTIVE ALARM hierarchy.

EvapFlowProof is the flow switch interlock. Closing the flow switch and therefore proving the existence of chilled water flow resets this trip. It is recommended that these settings not be changed.

LowAmbientLock applies to units with air-cooled condensers and prevents unit operation below the setting. The available range is -2°F to 60°F with a default of 35°F.

Set Air-Cooled Condenser Fans

Water-cooled = No

SET FANS SPs (1) Fan Stages=X Speedtrol=Yes/No

SET FANS SPs (2) Stage ON psi #1/2 #3/4 #5/6 #7/8 XXXX XXXX XXXX XXXX

SET FANS SPs (3) Stage Off psi #3/4 #5/6 #7/8 XXXX XXXX XXXX

The SET FANS SP screens 2 through 5 establish the discharge pressures that will stage the condenser fans on and off. These screens apply only to units set up for use with air-cooled condensers (WaterCooled=No). On such units, the settings do not have to be entered if the unit controller is not used to stage condenser fans for head pressure control. If the MicroTech II unit controller is not used to control the fans, some other method must be used.

Set Cooling Tower Control

The MicroTech II controller is capable of controlling cooling tower water temperature on chillers using water-cooled condensers. Output wiring connection points are shown on the field wiring diagrams.

[Water Cooled = Y] - Condenser Pump on with first Compressor on. Tower fan control is active when the Tower Control setpoint is set to Temperature and the condenser pump is in

44 WGZ 030A through 120A OM WGZ-2

the RUN state. Staging is based on Entering Condenser Water Temperature (ECWT). Operation depends on the following parameters. Condenser pump state

• ECWT OR Lift pressure

• Stage up and stage down timer values

• Tower setpoints (Tower Control, Tower Stages, Stage Up Time, Stage Down Time,

Stage Differential, Stage #1 ON, Stage #2 ON, Stage Down @, Stage Up @)

When the condenser pump starts, the stage up timer shall start. The first stage shall turn ON when the following conditions are met:

• The stage up timer completes

• The ECWT is > Stage #1 ON setpoint

• Bypass valve position is > the Stage Up @ setpoint (only if Valve/VFD Control setpoint

= Valve Stage)

Additional stages can turn on (up to the number specified by the Tower Stages setpoint) when above conditions are met for the next stage plus the following condition:

• VFD Speed is > the Stage Up @ setpoint (only if Valve/VFD Control setpoint = VFD Stage OR Valve SP/VFD Stage)

Down staging shall occur when the following conditions are met:

• The stage down timer completes

• The ECWT is < Stage #X ON (Temp) setpoint – Stage Differential (Temp) setpoint

point

• Bypass valve position is < the Stage Down @ setpoint (only if Valve/VFD Control setpoint = Valve Stage)

• VFD Speed is < the Stage Down @ setpoint (only if Valve/VFD Control setpoint = VFD Stage OR Valve SP/VFD Stage)

Each stage up or stage down event shall restart both the stage up and stage down timers. Only one fan output shall be switched at a time (except that all outputs switch OFF when the condenser pump state equals OFF).

OM WGZ-2 WGZ 030A through 120A 45

SET TOWER SPs (1) Tower Control= None Tower Stages = X StageUP/DN=XXX/XXX%

When Tower Control is None the control of condenser water temperature is not by the MicroTech II controller and assumed to be furnished elsewhere.

Tower Stages is the number of tower fans to be staged by the controller, choices are 0, 1, or

2. "0" indicates control will be by a bypass valve or variable speed pump controlled by the MicroTech II controller.

StageUP/DN imposes a time delay between fan stages when turning on or turning off.

SET TOWER SPs (2) Stage ON (Temp)°F

#1 #2

XXX XXX

Stage ON Temp is the entering condenser water temperature (ECWT) that will turn on tower fan #1 and #2. Default settings are 70°F and 75°F. Cold condenser water will improve unit efficiency but too cold can cause erratic operation. Settings below 60°F are not recommended.

SET TOWER SPs (3) StageDiff = XX.X°F

Stage Up Tmr=XX min StageDn Tmr=XX min

StageDiff is the number of degrees below the Stage ON that will turn off the tower fans. For example, if Stage ON #1 is 70°F and StageDiff is 5°F, tower fan #1 will stage off when the ECWT drops to 65°F and stage the fan on when the ECWT rises to 70°F. T he same is true for fan #2.

Stage Up timer is the number of minutes that must elapse between the condenser pump starting (it starts with the unit) and fan #1 starting or the time between fan #1 starting and fan #2 starting.

StageDown is the elapsed time between staging down the fan motors.

SET TOWER SPs (4) Valve/VFD Control=

ValveSP/VFDStage

Valve Type = NC

Valve/VFD Control settings are None, Valve Setpoint, Valve Stage, VFD Stage, or ValveSP/VFDStage. Default is None which results in no control of the tower from the MicroTech II controller.

• Valve Setpoint as established by the Set Tower SPs in screen (5) below.

This mode is operational when the Valve/VFD Control setpoint is set to Valve Setpoint OR Valve SP/VFD Stage. In this mode the valve output is varied with a proportionalderivative (PD) algorithm (with deadband) in order to maintain the controlled parameter (CP) at the desired value. The output is always limited between the Valve

46 WGZ 030A through 120A OM WGZ-2

, the valve will control (bypass tower) to hold the minimum temperature

Control Range (Min) setpoint and the Valve Control Range (Max) setpoint. A valve increment shall be computed once every 5 seconds according to the following equation. (Error Gain and Slope Gain are set in menu screen #8.)

Increment = [(Error) * (Error Gain setpoint)] + [(Slope) * (Slope Gain setpoint)] Where: Error = ECWT – Valve Setpoint Slope = (Present CP) – (Previous CP)

When the Error is > the Valve Deadband setpoint, the valve position analog output (% of full scale) is updated according to the following equation.

New %Position = Old %Position + Increment/10

• Valve Stage

, controls from the fan stage setpoint in use. It is recommended that the

Valve Setpoint method explained above be used rather than this mode. This mode is only operational when the Valve/VFD Control setpoint is set to Valve

Stage. In this mode the valve output is controlled as for Valve Setpoint mode (above), except that the active setpoint for the controlled parameter is selected according to the following table.

# Of Fans ON Active Setpoint

0 Valve Setpoint 1 Stage #1 ON 2 Stage #2 ON 3 Stage #3 ON 4 Stage #4 ON

• VFD Stage

, ValveSP/VFDStage, When the Valve/VFD Control setpoint is set to None, Valve Setpoint, OR Valve Stage, this output is set to 0. Otherwise, it will be controlled in a manner identical to Valve Stage Mode (above) except that (1) it shall be kept at zero until the first fan stage is ON, and (2) the following setpoints do not apply.

Valve Control Range (Min) Valve Control Range (Max) Valve Type

Valve Type settings are NC (normally closed to tower) or NO (normally open). These settings establish the operation of a tower bypass valve (must be a 3-way valve).

Initial Valve Position

When the condenser pump is not in the RUN state, the valve output shall be set as a function of entering condenser water temperature (ECWT) per the following graph.

OM WGZ-2 WGZ 030A through 120A 47

Figure 12, Initial Valve Position

Initial Valve Position

Max Position @

(values are examples only)

Setpoint

(90°F)

Min Position @

Setpoint

(60°F)

Min Start Position

Setpoint

(10%)

Max Start Position

Setpoint

(90%)

Operation Af ter Start

When the condenser pump is in the RUN state, the valve output shall be controlled in one of two modes as specified by the Valve/VFD Control setpoint. The controlled parameter shall be the condenser entering water temperature. When the desired output signal varies from 0 to 100%, the output voltage shall vary as shown below.

0 to 10 VDC (Valve Type = NC) 10 to 0 VDC (Valve Type = NO)

SET TOWER SPs (5) Valve SP = XXX °F Valve DB = XX.X °F

Valve SP is the minimum tower water temperature acceptable, default is 65°F. Valve DB is the dead-band in degrees, default is 2.0°F.

SET TOWER SPs (6) ValveStartPosition

Min = XXX% @XXX°F Max = XXX% @XXX°F

The ValveStartposition is the position of the valve when the unit starts. Default for minimum start position is 0%, and 100% for maximum position.

SET TOWER SPs (7) Valve Control Range

Min = XXX% Max = XXX%

Defaults are 10% minimum and 90% maximum.

SET TOWER SPs (8) PD Control Loop

Error Gain = XX Slope Gain = XX

Defaults are 25 for both error and slope.

48 WGZ 030A through 120A OM WGZ-2

TEST

TEST UNIT (1) Alarm Signal – Off Evap Water Pump=Off Cond Water Pump=Off

TEST UNIT (2) Liq Line Sol #1= Off Compressor #1=Off Compressor #3=Off

TEST UNIT (3) Liq Line Sol #2= Off Compressor #2=Off Compressor #4=Off

TEST UNIT (4) Hot Gas Sol #1-Off Hot Gas Sol #2-Off

TEST UNIT (5) Fan Motor #1=Off Fan Motor #2=Off Fan Motor #3=Off

TEST UNIT (6) Fan Motor #4=Off Fan Motor #5=Off Fan Motor #6=Off

TEST UNIT (7) Fan Motor #7=Off Fan Motor #8=Off

Editing Review

Editing shall be accomplished by pressing the ENTER key until the desired field is selected. This field shall be indicated by a blinking cursor under it. The arrow keys shall then operate as defined below.

CANCEL (Right) Reset the current field to the value it had when editing began. DEFAULT (Left) Set value to original factory setting. INCREMENT (Up) Increase the value or select the next item in a list. DECREMENT (Down) Decrease the value or select the previous item in a list.

OM WGZ-2 WGZ 030A through 120A 49

During edit mode, the display shall show a two-character wide menu pane on the right as shown below.

SET UNIT SPs (X) <D

(data) <C (data) <+ (data) <-

Additional fields can be edited by pressing the ENTER key until the desired field is selected. When the last field is selected, pressing the ENTER key switches the display out of “edit” mode and returns the arrow keys to “scroll” mode.

Alarms

When an alarm occurs, the alarm type, limit value (if any), date, and time are stored in the active alarm buffer corresponding to that alarm (viewed on the Alarm Active screens) and also in the alarm history buffer (viewed on the Alarm Log screens). The active alarm buffers hold a record of the last occurrence of each alarm and whether or not it has been cleared. The alarm can be cleared by pressing the Edit key. A separate buffer is available for each alarm (High Cond Pressure, Evaporator Freeze Protect, etc.). The alarm history buffer holds a chronological account of the last 25 alarms of any type.

Security

Two four-digit passwords provide OPERATOR and MANAGER levels of access to changeable parameters. Either password can be entered using the ENTER PASSWORD screen which can be accessed either through the SET OTHER menu or by simply pressing the ENTER key while on one of the SET screens. The password can then be entered by pressing the ENTER key, scrolling to the correct value with the UP and DOWN arrow keys, and pressing ENTER again. Once the correct password has been entered, the previously selected screen will reappear. Once a password has been entered, it will remain valid for 15 minutes after the last key-press.

BAS Interface

The MicroTech II controller is equipped with the Protocol Selectability™ feature, an exclusive McQuay feature that provides easy unit interface with a building automation system. If the unit will be tied into a BAS, the controller should have been purchased with the correct factory-installed interface module. The modules can also be added in the field during or after installation.

If an interface module was ordered, one of the following BAS interface installation manuals was shipped with the unit. Contact your local McQuay sales office for a replacement, if necessary.

• IM 735, L

• IM 736, BACnet® Communication Module Installation

• IM 743, Modbus® Communication Module Installation

ONWORKS® Communication Module Installation

50 WGZ 030A through 120A OM WGZ-2

Optional Controls

Phase/Voltage Monitor (Optional)

The phase/voltage monitor is a device that provides protection against three-phase electrical motor loss due to power failure conditions, phase loss, and phase reversal. Whenever any of these conditions occur, an input relay is deactivated, disconnecting power to the thermostatic control circuit. The compressor does a rapid shutdown including a pump down cycle.

The input relay remains deactivated until power line conditions return to an acceptable level. Trip and reset delays have been provided to prevent nuisance tripping due to rapid power fluctuations.

When three-phase power has been applied, the input relay should close and the “run light” should come on. If the relay does not close, perform the following tests.

1. Check the voltages between L1-L2, L1-L3, and L2-L3. These voltages should be approximately equal and within +10% of the rated three-phase line-to-line voltage.

2. If these voltages are extremely low or widely unbalanced, check the power system to determine the cause of the problem.

3. If the voltages are good, turn off the power and inter-change any two of the supply power leads at the disconnect switch.

This may be necessary, as the phase/voltage monitor is sensitive to phase reversal. Turn on the power. The relay should now close after the appropriate delay.

Factory settings are as follows:

Voltage Setting, set at nameplate voltage. Trip Delay Time, 2 seconds Restart Delay Time, 60 seconds

Hot Gas Bypass (Optional)

This option allows passage of discharge gas to the evaporator, permitting operation at lower loads than available with compressor unloading. It also keeps the velocity of refrigerant gas high enough for proper oil return at light load conditions.

The pressure regulating valve is a Sporlan SHGBE-8 and factory set to begin opening at 69 psig and can be changed by changing the pressure setting. The adjustment range is 0 to 100 psig. To raise the pressure setting, remove the cap on the bulb and turn the adjustment screw clockwise. To lower the setting, turn the screw counterclockwise. Do not force the adjustment beyond the range it is designed for, as this will damage the adjustment assembly. The regulating valve opening point can be determined by slowly reducing the system load while observing the suction pressure. When the bypass valve starts to open, the refrigerant line on the evaporator side of the valve will begin to feel warm to the touch.

WARNING

The hot gas line can become hot enough to cause personal injury in a very

short time; care should be taken during valve checkout.

OM WGZ-2 WGZ 030A through 120A 51

Troubleshooting Chart

PROBLEM POSSIBLE CAUSES POSSIBLE CORRECTIVE STEPS

Compressor Will Not Run

Compressor Noisy or Vibrating

High Discharge Pressure

Low Discharge Pressure

High Suction Pressure

Low Suction Pressure

Little or No Oil Pressure

1. Main switch, circ ui t breakers open.

2. Fuse blown.

3. Thermal overloads tri pped or fuses blown.

4. Defective contactor or coil.

5. System s hut down by equipment protection devices.

6. No cooling required.

7. Liquid line solenoid will not open.

8. Motor electrical trouble.

9. Loose wiring.

1. Flooding of refrigerant into crankcase.

2. Improper piping support on suction or liquid line.

3. Worn compressor.

1. Condenser water insuffic i ent or temperature too high.

2. Fouled condenser tubes (water-cool ed condenser). Clogged spray nozzles (evaporative condenser). Dirty tube and fin surface (air cooled c ondenser).

3. Noncondensables in s ys tem.

4. System overc harge with refrigerant.

5. Discharge shutof f valve partially closed.

6. Condenser undersized (air-cooled).

7. High ambient condi tions.

1. Faultly condenser temp. regulation.

2. Insuffic i ent refrigerant in system.

3. Low suction pressure.

4. Condenser too large.

5. Low ambient conditions.

1. Excessive load.

2. Expansion valve overfeeding.

1. Lack of refrigerant.

2. Evaporator dirty.

3. Clogged liquid line fil t er-dri er.

4. Clogged suction li ne or compressor suction gas strainers .

5. Expansion valve malfunc tioning.

6. Condensing temperat ure too low.

7. Compressor will not unload.

8. Insufficient water flow.

1. Clogged suction oil strainer.

2. Excessive liquid in crankcase.

3. Low oil level.

4. Flooding of refrigerant into crankcase.

1. Close switch

2. Check electri cal circuits and m otor winding for shorts or grounds. Investigate for possi ble overloading. Replace fuse or reset breakers after fault is corrected.

3. Overloads are auto reset. Check unit closely when unit comes back on line.

4. Repair or replace.

5. Determine type and cause of shutdown and correct it before resetting protection switch.

6. None. Wait until unit calls f or cooling.

7. Repair or replace coil.

8. Check mot or f or opens, short circuit , or burnout.

9. Check all wire junctions. Tighten all terminal screws.

1. Check superheat setting of expansion

valve.

2. Relocate, add or rem ove hangers.

3. Replace.

1. Readjust tem perature control or water

regulating valve. Investigat e ways t o increase water supply.

2. Clean.

3. EPA purge the noncondensables.

4. Remove excess refri gerant .

5. Open valve.

6. Check condenser rati ng tables against

the operation.

7. Check condenser rati ng tables against

the operation.

1. Check condenser c ont rol operation.

2. Check for leaks. Repair and add charge.

3. See corrective s teps for low suction

pressure below.

4. Check condenser rati ng table against the

operation.

5. Check condenser rati ng tables against

the operation.

1. Reduce load or add additional

equipment.

2. Check remote bul b. Regulate superheat.

1. Check for leaks. Repair and add charge.

2. Clean chemically.

3. Replace cartridge(s).

4. Clean strainers.

5. Check and reset for proper superheat.

Replace if necessary.

6. Check means for regulating condensing

temperature.

7. See corrective s teps for failure of

compressor to unload.

8. Adjust flow.

1. Clean.

2. Check crankc ase heater. Reset

expansion valve for higher superheat. Check liquid line solenoid valve operation.

3. Add oil.

4. Adjust thermal expansion valve.

52 WGZ 030A through 120A OM WGZ-2

PROBLEM POSSIBLE CAUSES POSSIBLE CORRECTIVE STEPS

Compressor Loses Oil

Motor Overload Relays or Circuit Breakers Open

Compressor Thermal Switch Open

Freeze Protection Opens

1. Lack of refrigerant.

2. Velocity in risers too low (A-C only).

3. Oil trapped in line.

1. Low voltage during high load conditions .

2. Defective or grounded wiring in m otor or power circuits.

3. Loose power wiring.

4. High condensing temperature.

5. Power line fault causi ng unbal anced voltage.

6. High ambient temperature around the overload relay

1. Operating beyond design condit i ons.

2. Discharge valve partiall y shut.

1. Thermostat s et too low.

2. Low water flow.

3. Low suction pressure.

1. Check for leaks and repai r. Add refrigerant.

2. Check riser sizes.

3. Check pitch of l i nes and refrigerant velocities.

1. Check supply volt age for excessive line drop.

2. Replace compressor-motor.

3. Check all connec t i ons and tighten.

4. See corrective steps for high discharge pressure.

5. Check Supply voltage. Notify power company. Do not start until fault is corrected.

6. Provide ventilation t o reduce heat.

1. Add facilities so t hat conditions are within allowable limits.

2. Open valve.

1. Reset to 42°F (6°C) or above.

2. Adjust flow.

3. See “Low Suction Press ure.”

Warranty Statement

Limited Warranty

Consult your local McQuay Representative for warranty details. Refer to Form 93343285Y. To find your local McQuay Representative, go to www.mcquay.com.

OM WGZ-2 WGZ 030A through 120A 53

This document contains the most current pr oduct information as of this printing. For the most up-todate product information, please go to www.mcquay.com.

Post Office 2510, Staunton, Virginia 24402 USA • (800) 432-1342 • www.mcquay.com OM WGZ-1 (3/05)

McQuay WGZ 030AW Installation Manual

Specifications and Main Features

Frequently Asked Questions

User Manual