Parameter Generation and Control 9354-4250 Installation And Operation Manual

Parameter Generation and Control, Inc.

Black Mountain, North Carolina

[phone]

500-1000 CFM Air Handler

460V, 60 Hz

Model #9354-4250

Installation and Operation Manual

Customer
Serial #
Ship Date

Parameter Generation and Control, Inc.

P. O. Box 129 1054 Old US 70 West Black Mountain, NC 28711

[phone] [phone] FAX

.
.
.

PGC Inc. Horizontal 500-1000 CFM June 2006

Parameter Generation and Control, Inc.

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PGC Inc. Horizontal 500-1000 CFM June 2006

Inspection........................................................................................................................ 4

Installation....................................................................................................................... 4

Plumbing..................................................................................................................... 4

Electrical Connections................................................................................................7

Electrical Connections................................................................................................8

Operation......................................................................................................................... 9

Turning the Chamber Off and On............................................................................... 9

Process Variable Display.......................................................................................... 10

Adjusting Set Points.................................................................................................. 10

Operation After Loss of Power................................................................................. 10

Fault Displays ........................................................................................................... 11

Control Modes .......................................................................................................... 12

Specifications, 500-1000 CFM..................................................................................... 13

Replacement Parts, 500-1000 CFM.............................................................................. 14

Appendices

Appendix A – Technical Information
Appendix B – SmartPad™ Operation Manual
Appendix C – Diagrams
Appendix D - Manuals for Accessory Equipment

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PGC Inc. Horizontal 500-1000 CFM June 2006

Inspection

If the equipment is damaged upon receipt, immediately request the delivering carrier to
perform an inspection and prepare a report. All claims for damage must be made against
the delivering carrier. Report the nature and extent of the damage to PGC, 828-669-8717,
and include instrument serial and catalog numbers to facilitate repair or replacement.

Installation

The 500-1000 CFM Conditioner was designed to be located adjacent to or on top of the
chamber to be conditioned. Allow at least 36 inches on the right side and front of the unit
for service. The location must be convenient to an adequate process water supply, drains
and electrical power. The conditioner must be reasonably level for proper water level
control.

Electrical power and water must be connected to this unit prior to operation. The required
voltage and current are listed on the nameplate located on the unit. The sump drain may
be connected directly to a facility drain, but the condensate drain must be connected to an
open (vented) trapped drain (see Figure 3) to ensure that backpressure on the facilities’
drain does not prevent proper drainage.

Note

The condensate drain has been supplied with a copper trap.

Plumbing

To prevent damage to the water pump and water heater, the unit must not

CAUTION

be operated until water is supplied to the unit and the sump has filled to the
proper level.

Process Water Supply Specifications

Units Maximum Typical Minimum

Process Water Pressure PSIG (Bar)
Process Water Daily

Gallons (Liters)

125 (8.6) N/A 5 (0.35)

5.0 (19) 1.5 (5.7) 0 (0)

Consumption
Condensate Production

Gallons (Liters)

5.0 (19) 1.5 (5.7) 0 (0)

per Day
Sump Water Volume Gallons (Liters)

15 (57) 15 (57) 6.6 (25)

Process Water Inlet

Connect a clean water supply line through an external customer-supplied hand valve to
the Process Water Inlet connection on the rear of the conditioner; this is a ½” male NPT
connection.

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PGC Inc. Horizontal 500-1000 CFM June 2006

Condensate Drain

Connect the condensate drain to an open (vented) trapped external drain. This drain is a
¾” female copper sweat connection on the rear of the conditioner.

Sump Drain

Connect the sump drain to a facilities
drain. This drain does not require a trap.
This drain connection is made to the ¾” ¼
turn ball valve, supplied on the rear of the

Coolant Water

Outlet

conditioner.

Coolant Water Supply and Return

If the refrigeration system is equipped
with a water-cooled condenser. Connect
coolant water to the condenser inlet
connection on the rear of the chamber
cabinet. Connect the coolant water return
line to the coolant water outlet connection.

Coolant Water

Inlet

Coolant flow requirements will vary based
on the operating conditions of condensing
units, as the temperature of the coolant fluid.
The following graph indicates the maximum

Coolant Water Connections

500-1000 CFM

coolant flow requirements for the condenser.

Maximum Condensor Water Flow Requirements

5.00

4.00

3.00

2.00

Gallons Per Minute

1.00

0.00
45 50 55 60 65 70 75 80 85 90 95 100 105

500-1000 CFM

Entering Water Temperature (Degrees F)

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PGC Inc. Horizontal 500-1000 CFM June 2006

Filling the sump

To fill the conditioner with water, ensure
that the sump drain valve is closed and open
the customer-supplied external water inlet
valve. When the sump is filled to the proper

Process Water

Inlet

level, a mechanical float valve will
automatically shut off the flow and maintain
the proper water level during operation. The
float valve is preset at the factory to
maintain the proper level (1/2” above the
evaporator tubing); to change the water

Condensate

Drain

level, adjust the angle of the float arm
slightly.

A low-water safety switch is located in the
front, left corner of the sump. This switch
will open when the water level is too low for
safe operation of the pump and water heater.
When the water level is correct, the float

Plumbing Connections

Service

Drain

switch will close and allow the controller to
resume operation of the unit.

The water fill valve float may be padded to prevent damage during

CAUTION

shipping. Remove the padding before connecting the water supply to the
inlet.

NOTE

The conditioner will not operate until the low water level safety is satisfied.

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PGC Inc. Horizontal 500-1000 CFM June 2006

CAUTION

Do not connect the drain connection to an un-vented drain.

NOR

Ensure that the drain connection is vented, as shown below.

OR

“Open” (Vented) Drain Connections

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PGC Inc. Horizontal 500-1000 CFM June 2006

Electrical Connections

Turn all electrical switches, circuit breakers, and motor starter protectors

CAUTION

(MSPs) off to prevent accidental starting of equipment when power is
connected.

Determine voltage and current requirements of equipment before making

NOTE

electrical connections. This information is on a data plate attached to the
machine.

Connect the air handler in accordance with all applicable codes, using a customer­supplied disconnect device.

The SmartPad™ user interface and the optional circular chart recorder can be located
remote from the air handler. Typically, the controller is located on the front of the
chamber to be controlled. These components are usually disconnected for shipment and
must be re-connected prior to operation. Refer to the attached wiring diagrams for re­connection information.

The SmartPad™ user interface interconnect cable has a maximum voltage

NOTE

of 24VDC. Refer to local codes to determine the proper conduit
requirements for the control cable.

The optional circular chart recorder can be powered by 24VDC or
120/230VAC. Refer to the wiring diagrams or the data plate on the
recorder for more information.

CAUTION

The compressor and blower will not
operate properly and may be damaged if
permitted to run backward. After the
Conditioner has filled with water and is
operating, observe the rotation of the
blower through the air bypass damper.
Ensure that the blower is turning as
indicated in the diagram below. If
necessary, turn off the wall disconnect and
interchanging any two phase wires at the
wall disconnect or of the line connection terminals. Exchanging

phases at this point will reverse the rotation of all 3-phase motors.

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PGC Inc. Horizontal 500-1000 CFM June 2006

Operation

The 500-1000 CFM Conditioner is a self-contained conditioner designed to control dry­bulb temperatures over a range of 7°C - 60°C (44.6ºF - 140ºF), dependent upon the size

and construction of the test chamber. The dry-bulb temperature is held to ± 0.2°C and
relative humidity constancy to ± 0.5% with dew points above 5°C (41°F).

The SmartPad™ may be remotely mounted; refer to the PGC SmartPad™ section at the
rear of this manual for instructions.

Operating Range

Turning the Chamber Off and On

When the chamber is energized and the Standby key has been pressed, the system
should begin to operate and control the temperature and humidity in the chamber at the
set points entered into the SmartPad™ user interface.

The SmartPad™ user interface is configured with a Standby key located in the lower
right corner of the keypad. Pressing this key will disable the system and place the
controller in a Standby mode. The SmartPad™ display will indicate:

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PGC Inc. Horizontal 500-1000 CFM June 2006

STANDBY MODE

Press the ON/OFF key

to energize the system

When the system is in Standby mode, it can be energized by pressing the Standby key

Process Variable Display

The Process Variable screen is the first screen that will be displayed when the conditioner
is energized. This screen will display the measured process variables and will allow
access to the other screens in the SmartPad™.

The bottom line of the SmartPad™ display is a label for the four function keys on the key
pad. This label will vary from screen to screen to reflect the action of each of the function
keys.

Refer to the SmartPad™ manual in the appendix for a complete listing and discussion of
available screens.

Adjusting Set Points

In the Process Variable screen, pressing the SP function key will access the Set Point
screen. The Set Point screen will allow the user to enter the desired air temperature and
relative humidity set points for the chamber.

The SmartPad™ has no ENTER key. In order to enter a value in any field

NOTE

all digits must be entered. For example, to enter 25.0°C air set point you
must press “2”, “5” and “0”. When the field has been filled and the data has
been entered, the cursor will jump back to the beginning of the field.

Operation After Loss of Power

If power is removed from the conditioner, the controller will resume operation in the
same mode when power is regained. For instance, if the SmartPad™ was in Standby
mode when power was lost, it will be in Standby mode when power is restored. If the
SmartPad™ was operating and controlling the chamber, it will return to that mode of
operation.

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PGC Inc. Horizontal 500-1000 CFM June 2006

The SmartPad™ is not equipped with a battery backup.

NOTE

All set points, tuning values and ramping profiles are stored in non-volatile
memory and will be permanently stored in the SmartPad™.

If power is removed from the controller it will resume operation when
power is restored.

In Steady State set point mode the controller will resume operation at the
previous steady state set points.

In Programmable set point mode the controller will resume operation at
exactly the same segment and time remaining in that segment if the

duration of the power loss is less than approximately 20 minutes. If the
duration of the power loss exceeds approximately 30 minutes the

controller will re-initiate the program according to the loop parameters
defined in the INIT screen.

Fault Displays

If the system encounters a temperature, low-water, remote on/off switch, or refrigerant
pressure fault, the system will shut down and the SmartPad™ will indicate the fault that
has occurred. The SmartPad™ will continue to indicate that the fault exists, and will
indicate if/when the fault has cleared.

If the fault has been cleared, the system can be re-energized by pressing the Standby key

. If the fault has not cleared, the source of the fault must be determined and corrected

before the system can be re-energized.

Some faults will clear automatically and others will require user

NOTE

intervention.
Regardless of the fault clearing mechanism, the user must press the Standby

key in order for the conditioner to resume operation.

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PGC Inc. Horizontal 500-1000 CFM June 2006

Control Modes

The PGC conditioning system offers four modes of temperature and humidity control.

1. Cascade Temperature Mode

This is the most commonly used mode because the user specifies only the desired
air temperature and relative humidity (Rh) level in the chamber. The temperature
of the water spray controls the dew point of the discharge air and the water
temperature is adjusted in order to achieve desired humidity level. The air is then
re-heated to the desired temperature before returning to the test chamber. This
allows the system to respond to load variations while retaining the basic stability
of a spray system.

2. Two-Temperature Mode

In this mode, the user establishes the desired air and water temperatures that are
required to produce the desired relative humidity level, as determined by a
psychometric chart. The Two-Temperature mode can be used when operating the
very edges of the system capabilities.

3. Slow Damper Mode

This mode is similar to Cascade mode with the difference being that the air
bypass damper control loop and the air heater control loop have been separated.
In this mode the damper is moved slowly and its final position is when the desired
percentage of air heat output is achieved. The desired percentage of air heat is
determined by the user in the tuning parameters (Manual Adjust) section of the
controller. In some situations, slow damper mode can be applied to improve
energy efficiency or extend the operating range of the system. Typically, slow
damper mode is most effective when the system is operated at a single condition
as it will often require manual tuning adjustments for proper operation at multiple
set points.

4. Dry Mode

This mode is required to control dew points below 4°C. In this mode, all water is
removed from the spray chamber and an optional desiccant dryer is used to
control humidity. Although this mode is accessible in SmartPad, it is non­functional unless the system is equipped with a desiccant dryer.

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PGC Inc. Horizontal 500-1000 CFM June 2006

Specifications, 500-1000 CFM

Voltage-------------------------------------------------------------------------------- 460V~
Frequency----------------------------------------------------------------------3ph, 60 hertz
Current------------------------------------------------------------------------------ 8.8 FLA
Circuit Capacity (Max / Min)--------------------------------------------------30A / 12A
Heater, Water ------------------------------------------------------------------- 1800 watts
Heater, Air (Two, 1500 watt) ------------------------------------------------- 3000 watts
Refrigerant-------------------------------------------------------------R-404a, 96 Ounces.
Process Water Pressure, (Max/Min) ------------------------------------------125/5 psig
Weight Net --------------------------------------------------------------------------1000 lb.
Weight Shipping--------------------------------------------------------------------1400 lb.
Temperature Range -------------------------------------------------------------7° to 60°C
Relative Humidity Range----------------------------------------------------10% to 95%

1

Temperature Constancy (control) ------------------------------------------------ ± 0.2°C
Rh Constancy (control) ----------------------------------------------------------± 0.5%

1

Minimum Rh is limited by a minimum dew point of 5°C (41°F) for standard Spray

Mode. For example:

Air

Max. Rh Min. Rh

Temperature

10°C (50°F) 88% 70%
25°C (77°F) 93% 32%

40°C (104°F) 95% 17%

> 50°C

95% 10%

(122°F)

Parameter Generation and Control, Inc.

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PGC Inc. Horizontal 500-1000 CFM June 2006

Replacement Parts, 500-1000 CFM

Description Mfg. / Supplier Mfg./Supplier # PGC #

ACE Master Micro Controller PGC ACE 503g N/A
ACE4 Controller Assy. PGC OEM 6000-1559
ACE4 Power Supply Meanwell PS45-24 1607-0024
Circuit Breaker,1 Pole, 2AMP Siemens 5SX2102-8 0426-1020
Circuit Breaker,2 Pole, 2AMP Siemens 5SX2202-8 0426-2020
Compressor Copeland CS14K6E-TFD-230 1510-0298
Contactor Siemens 3RT1025-1BB40 0419-0948
Damper Drive Motor Actuator Belimo

OEM

1608-

0916A
Door, Spray Chamber, Inner PGC N/A 6000-0303
Door, Spray Chamber, Outer PGC N/A 6000-0392
Evaporator Coil, 5/8 OD x .032 wall Super Radiator Co. OEM 1244-0066
Filter Bag,5 Micron, Polyester McMaster-Carr 9316T22 0215-1800
Fuse, Door Heat 5A Bussman FNM5 0409-0123
Gasket, Return Duct Transition

Refrig. Hardware 47-131 1604-0101
Box, 140”
Gasket, Spray Chamber Inner

Refrig. Hardware 47-131 1604-0101
Door, 95”
Gasket, Spray Chamber Outer

Refrig. Hardware 47-131 1604-0101
Door, 95”
Gasket, Supply Duct Transition Box Refrig. Hardware 47-131 1604-0101
Heater, Air Vulcan OEM 0416-0508
Heater, Water Watlow OEM 0416-0599
Hour meter, UV Durant E42DIR48230 0215-2821
HygroClip Connector and Cable,
5 meters, amplified analog, 0ºC to

PGC MOK-05-XX-005V-1-

DIO

1636-0159

100ºC
HygroClip Micro Controller PGC Hygro 503 N/A
HygroClip T/Rh Transmitter,

PGC OEM

1608-0865b

Full-Range Calibration
HygroClip T/Rh Transmitter,

PGC OEM

1608-0865a

Single-Point Calibration
HygroClip T/Rh Transmitter, Un-

Rotronic HygroClip S 1608-0865
calibrated
HygroPalm Calibration Cable PGC AC1620-modified 1609-0866
HygroPalm Calibrator Rotronic HygroPalm 2 1609-0865
Latches, Access Panel Southco 62-43-251-3 1008-0080
Latches, Inner Doors Southco OEM 1001-0082
Latches, Outer Doors McMaster-Carr 5481K19 1009-1017
Mist Eliminator PGC N/A 5000-0135
Motor Protector Siemens 3RV1021-1KA10 0427-1250
Motor Protector Siemens 3RV1021-0GA10 0427-0063

Parameter Generation and Control, Inc.

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PGC Inc. Horizontal 500-1000 CFM June 2006

Description Mfg. / Supplier Mfg./Supplier # PGC #

Motor Protector Siemens 3RV1021-1BA10 0427-0200
Motor, Blower Continental Fan RO-TMK280-2-34 1602-0199
Pump March TE5.5CMD 1619-0091
Refrigeration Dryer, Filter Sporlan CW-165S 0215-0887
Relay , Solid State, Door Heat Omron G3NE-210T-US 0416-0414
Relay, Solid State, 4-28 VDC Continental RVDC/6V25 0416-0403
Sensor , Door Jamb Temperature JMS Southeast OEM 1607-0652
Sensor ,Water Temperature JMS Southeast 3ESCK6BZZ3120JYTA1619-0862
SmartPad™ controller PGC OEM 1607-1100
SmartPad™ Micro Controller PGC Spad 503D N/A
Spray Nozzle Spraying System NO. 1/4A-SS5-15. 1612-0201
Stepper Micro Controller PGC Step 503 (SDR3) N/A
Strainer, Bronze “Y” McMaster-Carr 43935K24 0215-0904
Supply Duct Transition, 10” Round PGC N/A 5000-1389
Surge Suppressor Siemens 3RT1936-1TR00 0419-0891
Switch, Float Gems LS1750-192-908 0421-0060
Switch, Hi-Lo Refrig Pressure Copeland 085-CP2M-7K 0423-0683
Thermostat, Safety Thermtrol TS-120SR 30F-240F 1636-0223
Timer, Chamber Light Intermatic FF60MC 0419-0355
Transformer Micron B100MBT713XK 0419-0326
UV Lamp Severn Trent Water 5340UD 0215-2825
UV Lamp Power Supply Severn Trent Water 20697UD 0215-2831
UV Lamp Quartz jacket Severn Trent Water 2450UD 0215-2824
UV Plastic Support PGC OEM 0215-2826
Valve, Expansion, Body Danfoss 068U2287 0215-0872
Valve, Expansion, Cartridge Danfoss 068U1037 0215-0777
Valve, Hot Gas Temp Control Sporlan SDR-3-20-S 0215-0873
Valve, Sump Float Hawkeye Steel

UFV600 0209-0050

Products

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Parameter Generation and Control, Inc

Precise Humidity Control

Notes:

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www.humiditycontrol.com
[e-mail]

[phone]

Fax [phone] [phone]

Black Mountain, North Carolina

PGC, Inc 500-1000 CFM Air Handler May 2006

Appendix A

System Construction ................................................................................................................... 2

Theory of Operation.................................................................................................................... 3

Description of Operation............................................................................................................. 4

Measurement of Test Chamber Conditions ............................................................................ 4

Air Flow.................................................................................................................................. 4

Water Flow ............................................................................................................................. 5

Temperature Controls ............................................................................................................. 5

Description of Circuitry .............................................................................................................. 7

Safety Devices............................................................................................................................. 9

Troubleshooting ........................................................................................................................ 12

Operating Range of the System. ........................................................................................... 12

Water Temperature ...............................................................................................................12

Air Temperature.................................................................................................................... 13

Water Level .......................................................................................................................... 13

Rh Control ............................................................................................................................ 14

Maintenance .............................................................................................................................. 15

Preventive Maintenance Schedule........................................................................................ 15

Automatic Damper Motor Adjustments ............................................................................... 18

Calibration ............................................................................................................................ 18

Calibration ............................................................................................................................ 19

Calibration, Air/Rh ............................................................................................................... 19

Water Temperature Calibration ............................................................................................ 22

Appendix A A-1

PGC, Inc 500-1000 CFM Air Handler May 2006

SYSTEM CONSTRUCTION

The 500-1000 CFM Conditioner consists of four main sections:

1. Conditioning Compartment: spray bypass damper, blower, spray eliminators, spray

jets, water sump, low water level safety float switch, process water float valve, stirring
jet, evaporator coil, and particulate filter

2. Mechanical Compartment (side access panels): refrigeration condenser, compressor,

receiver, , high- and low-pressure safety switches, filter/dryer, hot gas bypass valve,
water pump, water heater, water RTD, Programmable Logic Controller (PLC), and power
panel with terminal strips, circuit breakers, motor starter, and contactors

3. Conditioner Exterior: sump drain valve, air bypass damper actuator, UV filter, and air

temperature safety thermostat.

4. Control Enclosure: SmartPad™ user interface and optional chart recorder.

The unit is sturdily constructed, with a stainless steel interior and exterior, and insulated door
with heavy refrigerator-type latches and vapor-resistant seals. Double walls separated by
insulation are used around the conditioning chamber. All internal seams are welded to preclude
saturation of the insulation.

The spray tree is a 3” stainless steel tube (spray header) with spray nozzles attached along the
sides, and a clamp on each end for sealing the tube. The clamp on the right end secures a blank
plate against an O-ring gasket. A UV lamp is inserted from the electrical compartment, through
the plate on the left end.

Appendix A A-2

PGC, Inc 500-1000 CFM Air Handler May 2006

THEORY OF OPERATION

PGC’s method of control is the
same for both reach-in
chambers and conditioning
systems. The environment to be
conditioned is controlled at a

Supply Air

targeted dew point temperature,
and then reheated to the desired
air temperature. This
methodology follows a proven
technique that maintaining a
constant dew point and air
temperature will produce a very
constant relative humidity. The
desired air temperature and
relative humidity or water

Blower

Air Filter

Return Air

Dampers

temperature are set via the
SmartPad™. If equipped with

Sprayed Coil

an optional recorder, it can be
wired to record the actual air
temperature and relative
humidity or water temperature.

Mechanical

The air is cooled by means of a
water spray which constantly
sprays water across the air
stream, saturating the air. A
submerged refrigeration
evaporator coil operates 1°C­2ºC (1.8°F-3.6°F) below the
desired dew point and cools the

Figure A-1 - Generic Conditioning Unit

water that is sprayed across the
air stream. The air is then re­heated before it is returned to
the test chamber.

NOTE

Dew point is the temperature at which the air can contain no more moisture and
some moisture begins to condense.

A portion of the air can be diverted around the water spray saturator by a bypass damper. If the
air does not pass through the water spray, it will not be cooled; if the air is not cooled, it will not
require as much (if any) air heat to be applied before it is returned to the test chamber. The
amount of air that passes through the saturator, or bypasses the saturator, is determined by the air
temperature control loop.

Appendix A A-3

PGC, Inc 500-1000 CFM Air Handler May 2006

DESCRIPTION OF OPERATION

The 500-1000 CFM Conditioner is a self-contained conditioner designed to control dry-bulb
temperatures over a range of 7°C – 60°C (44.6ºF - 140ºF), dependent upon the size and
construction of the test chamber. The dry-bulb temperature is held to ± 0.2°C and relative
humidity constancy to ± 0.5% with dew points above 5°C (41°F).

The temperature of the water spray saturator controls the dew point of the discharge air. When in
Rh Cascade or Slow Damper mode, the water temperature in the saturator is varied slowly in
response to a humidity control system. This allows the system to respond to wide load variations
while retaining the basic stability of a spray system. When in Two-Temperature mode, the user
establishes the air and water temperatures.

M

EASUREMENT OF TEST CHAMBER CONDITIONS

Precise control of temperature and humidity within the test chamber is obtained by accurately
measuring the dry-bulb temperature and the dew point temperature of the air in the test chamber
or the duct. The temperature of the water in the spray chamber controls the dew point
temperature, and is measured prior to the spray nozzles.

When operating in one of the spray modes, the dew point of the air exceeds the water temperature
by approximately 1°C for each 10°C difference between the air and water temperatures. During
the ramp portion of program cycling, the dynamic heat exchange process that takes place makes it
difficult to establish any exact relationship. When operating in the Two-Temperature mode, refer
to the air/Rh/water spray graph provided with the unit for air and water temperatures necessary
for the desired relative humidity.

A

IR FLOW

As the air enters the conditioner through the round, flexible duct connection in the removable top
cover. The process blower, located beneath this cover, will force the air into the conditioning
section. Entering the conditioning section, the air first encounters the by-pass damper; the
damper determines the volume of air that enters the saturator, and the volume that is bypassed
around the saturator. When the damper is fully closed, all of the air is forced through the water
spray. As the air passes through the water spray, it is saturated and cooled, nearly to the water
temperature. This method provides a stable dew point for the air as it leaves the saturator section.
The chilled and saturated air then passes through the water droplet eliminator to remove any free
moisture that may be present. The air then continues over the dry-bulb heaters, where it is heated
to the desired chamber air temperature (without affecting the dew point) and is returned to the
chamber through the round, flexible duct connection on the left end of the conditioner.

When the damper is fully open, most of the air bypasses the water spray and travels directly to the
air heaters. The bypassed air is then mixed with any air that traveled through the saturator section
and then returns to the test chamber. The spray bypass damper will be automatically positioned
by the actuator operating on a control signal derived from the duty cycle of the air heater. The
position of the damper can range from 0% to 100% open.

The dew point of the air stream is controlled even when most of the air is bypassed around the
water spray saturator. The air bypass damper is not 100% efficient, allowing some air to enter the
water spray saturator even when closed.

Appendix A A-4

PGC, Inc 500-1000 CFM Air Handler May 2006

In Slow Damper mode, the position of the damper is load dependent; the damper
will change slowly to achieve the desired conditions. The damper will also change

NOTE

position in order to compensate for droop or overshoot in the air temperature
control loop.

W

ATER FLOW

The water pump is located in the right section of the cabinet (accessible through the front or side
access doors). The water is picked up by the pump and heated, and then forced across the water
temperature sensor (100Ω platinum RTD) and into the spray header in the spray chamber. The
spray header is situated to spray water across air stream. The remainder of the water passes
through the particulate filter to remove debris.

T

EMPERATURE CONTROLS

The water temperature is sensed immediately prior to entering the spray headers, and the air &
humidity are measured by the HygroClip™ T/Rh transmitter that is located in the air stream.

The air heaters are positioned in the air-stream path between the chamber and the saturator. The
amount of heat applied is controlled by the dry-bulb control system with the sensing element in
the air stream. The duty cycle (the percentage of heat applied) for the air heater can be accessed
from the SmartPad™.

The water in the sump is cooled by the refrigeration evaporator, and is then sprayed across the air
stream to cool and saturate the air. Since the refrigeration system has a greater capacity than is
needed for most conditions, a hot gas bypass valve is provided to modulate the refrigeration
capacity as required. This valve is automatically adjusted by an actuator operating on a control
signal derived from the duty cycle of the water temperature control loop; the more the hot gas
valve opens, the more the refrigeration capacity is reduced. The relative position of the hot gas
bypass valve is represented by the water heater output percentage: Zero (0%) out is full
refrigeration capacity (hot gas bypass valve closed); one hundred percent (100%) out is minimum
refrigeration capacity (hot gas bypass valve open).

There are four factors that limit or control Water Set Point:

1. Humidity Control Band

Water Set Point will change in order to control Rh. If the measured Rh value is less
than the Rh set point, the Water Set Point will increase in order to increase the Rh by
increasing the dew point. The maximum rate at which the Water Set Point will
change is adjustable; the most common Water Set Point Rate of Change is

0.25ºC/minute (the maximum value). The Water Set Point Rate of Change is
proportional to the deviation from Rh Set Point. For example, if the Rh control band
is +/- 10% and the measured Rh is 10% below Set Point (at 100% of the control
bandwidth), the water Set Point will change at the rate of 0.25°C/minute (the
maximum Rate of Change X 100%). If the measured Rh is 5% below the Rh Set
Point (at 50% of the control bandwidth), the water Set Point will change at the rate of

0.125ºC/minute (the maximum rate of change X 50%).

Appendix A A-5

PGC, Inc 500-1000 CFM Air Handler May 2006

2. Water Temperature Set Point Limits

Minimum and maximum Water Set Point limits are factory pre-set in order to prevent
freezing or overheating the pump.

3. Dew Point

Humidity is a function of air temperature and dew point, and the water temperature is
directly related to dew point The controller limits the Water Set Point to 1ºC < Air
Set Point to prevent a runaway temperature control. Without this limit, a runaway
condition could be experienced when operating the unit with a high humidity set
point. Such a setting could cause the water temperature to keep increasing in order to
achieve the humidity set point, which would have the side effect of increasing the air
temperature; this increase in air temperature would increase the capacity of the air to
hold moisture, such that the system would never reach the humidity set point.

4. Measured Water Temp

If the Rh Set Point is set above or below the current Rh control band, the Water Set
Point Rate of Change will automatically maximize to change the water temperature
as quickly as possible. Many variables affect how fast the water temperature will
change, such as the efficiency of the pump, how much water is in the sump, how
often the test chamber is opened, etc. These are beyond the capability of the control
system to measure; however, the controller measures how quickly the water
temperature is actually changing, regardless of the uncontrollable variables. When
the measured Rh is outside of the control band, the Water Set Point is changed
automatically:

Water Set Point = Measured Water Temp + Control Bandwidth

For example, assume that the unit is operating with a Water Set Point of 25ºC and the
water control bandwidth is 5ºC, with the humidity controlling at 50% with the control
bandwidth at 10%. If the Humidity Set Point is set above the upper level of the
control band (>60%), then:

Measured Water Temperature + the Water Control Band = new Water Set Point

In this example, the new water Set Point would be (25ºC + 5ºC=) 30ºC. This will
cause 100% water heater output, and the Water Set Point will continue to increase at
a value equal to the rate that the water temperature is changing. As soon as the
measured humidity value is back within the control band (in this example, when the
measured Rh is 65.01%), the Water Set Point will resume changing at the normal
rate.

Appendix A A-6

PGC, Inc 500-1000 CFM Air Handler May 2006

DESCRIPTION OF CIRCUITRY

Although this conditioner utilizes 24 volts DC for the control circuits, some

CAUTION

components require 120 or 460VAC; these voltages can be present even when the
conditioner is not operating.

CAUTION

Power to the unit should be removed at the wall disconnect prior to opening any of
the access panels.

Line voltage is applied to the 24 VDC power supply. The 24VDC power supply provides power
to the Programmable Logic Controller (PLC), the HygroClip T/Rh transmitter, the air bypass
damper actuator, safety devices, and the line contactor.

The PLC has an on-board DC-DC converter that will produce +5VDC for the board-level logic
components. A second DC-DC converter produces +15VDC for use by the SmartPad user
interface, stepper motor, and the RTD amplifiers.

When power is applied to the conditioner, and control circuit breaker(s) are closed, the SmartPad
user interface will be energized. If all of the safety devices are satisfied (pressure switches,
thermostats, float switches, etc.), then the conditioner can be energized by pressing the Standby

key on the SmartPad™ user interface. This will instruct the PLC to energize the line contactor
(1CON).

When 1CON is closed, power is applied to the motor starter protectors (MSPs) and the heater
circuit breaker. If the MSPs are closed, then the compressor, blower, and pump will be energized.
If the heater circuit breakers are closed, then the air and water heaters will be enabled. The
operation of the air heaters and water heater is controlled by the PLC; the PLC determines the
duty cycle (On time verses Off time) for each of the heaters, based on the requirements of each
temperature control loop. The PLC will open and close digital outputs that will control the input
signals to solid-state relays, which will apply power to the respective heater based on the
respective control loop. An LED on each relay will indicate the On or Off status of that particular
heater control loop.

The UV filter will also be enabled by the control circuit breaker(s). Any time power is applied to
the conditioner, the control circuit breakers are closed, and the unit is operational (i.e. 1CON is
closed), the UV filter should be energized.

On initial power up, the PLC will determine the hot gas bypass valve position by driving the
stepper motor to fully close (0% output) the hot gas bypass valve in order to “zero” the valve.
This involves driving the motor past the full closed position; the valve will be seated against the
full closed stop but is not damaged by this over driving maneuver. Bumping the valve against the
full-closed stop can correct for any “lost steps” or accumulated errors that could occur over time
due to the constant reversal of the stepper motor.

During normal operation, the position of the hot gas valve is based on the output percentage of
the water temperature control loop. This output percentage is translated into a percentage of
“open” value for the stepper motor. The PLC converts this percentage open value into a step
count that will position the valve accordingly. When the valve is adjusted to the desired position,
the PLC will cease to step the motor, and the motor will maintain its current position.

Appendix A A-7

PGC, Inc 500-1000 CFM Air Handler May 2006

The position of the air bypass damper is determined by the PLC based on the air output
percentage. The input to the damper actuator is a frequency modulated (FM) square-wave signal.
The damper will be positioned based on the frequency of the FM signal. A yellow LED on the
PLC indicates the duty cycle. Zero percent (0%) air heat output will produce a 0.59 second On
time pulse, which instructs the damper to move to the full spray position. One hundred percent
(100%) air heat output will produce a 2.93 second On time pulse, which instructs the damper to
move to the full bypass position. An On time between 0.59 seconds and 2.93 seconds will
produce a proportional response in the damper position.

The water temperature is measured using a positive-coefficient 100Ω Platinum RTD temperature
sensor. This sensor consists of a very thin Platinum wire that is wound around a ceramic core. As
the temperature of this wire increases, the resistance of the Platinum element increases linearly.
This resistance is placed in a bridge network to produce a linear voltage proportional to the
change in temperature. This voltage is then converted to a digital value that can be used by the
PLC by and the A/D converter.

The air temperature is also measured using a 100Ω RTD located in the HygroClip T/Rh
transmitter. A circuit in the HygroClip converts this RTD input to a digital signal that is
transmitted to the PLC using a single-wire serial interface. The PLC receives this digital signal
and converts it to a digital value that the PLC can use in its calculations.

The HygroClip also converts the RTD input into a 0-1VDC analog signal that is scaled so that

0.1VDC = 1°C. This analog signal is applied to an amplifier built into the HygroClip connection
cable, which converts the 0-1VDC signal into a 0-5VDC signal (0-5VDC is required if the analog
signal is transmitted more than 10 feet). The 0-5VDC amplifier can be used to scale the analog
output for different ranges; the most common range is (0-5VDC) = (0°C to 100°C). However,
amplifiers are available for (-30°C to +70°C) and (-40°C to +60°C). This 0-5VDC analog
amplifier is not used by the chamber controller, and is only required when an analog device (such
as a chart recorder) is connected to the system. This analog output is available on the chart
recorder connector of the PLC.

The relative humidity is measured using a thin-film polymer capacitive element that changes
capacitance as moisture is absorbed or given off. The HygroClip T/Rh transmitter will convert
this change in capacitance into a digital value. This digital value is transmitted to the PLC in the
same single-line serial interface as the air temperature measurement. The PLC will decode the
digital value and convert it to a digital value that can be used by the PLC. The HygroClip T/Rh
transmitter will also convert the measured Rh to a 0-1VDC analog output. The same analog
amplifier that is used in the analog air temperature output will convert the 0-1VDC signal to a 0­5VDC signal. In all instances, the Rh output will be scaled so that 0-5VDC will equal 0-100%
Rh. This analog output is also available at the chart recorder connection on the PLC.

A separate voltage to current converter is installed in the air handler electrical compartment for
both the air temperature and relative humidity. This device will convert the 0-5VDC analog
signal from the HygroClip to 4-20mA. The output will be scaled so that 4-20mA corresponds to
the same temperature or Rh range as the analog signal from the HygroClip (typically this will be
4-20mA = 0-100°C or 0-100% Rh). The 4-20mA signal is provided as an interface to a customer
supplied monitoring device. This converter is equipped with a zero and span calibration
potentiometer that can be field adjusted in order to match the 4-20mA output with the NIST
traceable temperature and Rh output from the HygroClip.

Appendix A A-8

PGC, Inc 500-1000 CFM Air Handler May 2006

SAFETY DEVICES

The unit is equipped with several safety devices to guard against serious trouble due to failure of
any components.

Alarm contacts are available on the PLC, which will switch when either of the process variables
is in an alarm condition. The process variables are Air and Water in Two-Temperature mode, or
Air and Rh in any other mode. The alarm type, set points, and time delay are all programmable
from the SmartPad™; and the alarm can be disabled from the SmartPad™; refer to the
SmartPad™ manual for further information. The alarm contact is a single-pole double-throw
(SPDT), Normally Open / Normally Closed, dry contact relay rated at 6 Amps @ 250VAC.

Compressor Internal Overload: The refrigeration compressor is equipped with an internal

thermal protector. If the compressor draws excessive current, the motor windings will overheat. If
the windings overheat, the internal thermal protector will open and the compressor will not
operate. The rest of the chamber will continue to function, although it is not possible to control air
or water temperature unless the compressor is operating. As soon as the internal temperature of
the compressor motor drops to a safe operating level, the compressor will resume operation. This
reset process will normally require about 45 minutes.

Several potential causes of a compressor internal overload include the loss of coolant water flow,
excessive coolant water temperature, clogged coolant water inlet filter, high ambient temperature,
or excessive refrigerant charge, low line voltage, or unusually high ambient temperature.

Refrigeration High Pressure Fault: A pressure switch monitors the discharge pressure in the

refrigeration system. This switch is located beside the compressor. If the pressure is allowed to
operate at an excessive level, the compressor will be damaged. If the high-pressure switch opens,
the SmartPad™ will pad indicate “HIGH PRESSURE FAULT SET” and the system will shut
down. The high-pressure switch will automatically reset after the refrigeration discharge pressure
falls below the pressure trip point. When the switch is reset, the SmartPad™ display will indicate
“HIGH PRESSURE FAULT CLEAR”, and the system may be restarted by pressing the Standby

key on the SmartPad™ key

Several potential causes of a compressor internal overload include obstructed or dirty air cooled
condenser, excessive refrigerant charge, low line voltage, or unusually high ambient temperature.

Refrigeration Low Pressure Fault A pressure switch monitors the suction pressure in the

refrigeration system. If this pressure is allowed to operate below a safe level, the compressor may
be damaged. If the low-pressure switch opens, the SmartPad™ will indicate “LOW PRESSURE
FAULT SET” and the system will shut down. The low-pressure fault will automatically reset
when the refrigeration suction pressure rises above the pressure trip point; when this occurs, the
SmartPad™ display will indicate “LOW PRESSURE FAULT CLEAR”, and the system may be

restarted by pressing the Standby key on the SmartPad™ key pad.

Some potential causes of a low-pressure fault include, but are not limited to, low refrigerant

charge, frozen evaporator, or a poor spray pattern.

Appendix A A-9

PGC, Inc 500-1000 CFM Air Handler May 2006

r

High Pressure

Reset

Low Pressure

Switch

High Pressure

Switch

Figure A-2 - Pressure Switches

Air Temperature

Safety Thermostat

Over Temperature Thermostat An air over-temperature safety

thermostat has been incorporated into the chamber. The temperature
adjustment for this device is located at the rear of the unit, on the side of
the heater housing. This safety thermostat is designed to protect the
contents of the test chamber from excessive temperature rise in the event
of a system failure. The operator may set this manually to protect the
product under test, normally 2-3°C (5°F) degrees above highest test
temperature. If this thermostat opens due to excessive temperature, the
chamber will shut down and the SmartPad™ user interface will indicate
“TEMPERATURE FAULT SET”. The thermostat will automatically
reset when the temperature inside the chamber drops below the cut-out
temperature. After the thermostat has reset, the SmartPad™ user interface
will indicate “TEMPERATURE FAULT CLEAR”, and the system may

UV Time

be restarted by pressing the Standby key on the SmartPad™ key pad.

Low-Water Safety Switch A low-water level safety float

switch is located in the front left corner of the sump, near the
floor of the sump; this switch will shut down the air handler if the

Figure A-3 – Low Water

Safety Float Switch

Condensate

water level in the sump falls below a safe operating level. If this
float switch opens, the air handler will shut down. The
SmartPad™ user interface will indicate “LOW WATER FAULT
SET”. The float switch will automatically reset when the water
level in the sump returns to a safe operating level. After the
switch has reset, the SmartPad™ user interface will indicate
“LOW WATER FAULT CLEAR”, and the system may be

restarted by pressing the Standby key on the SmartPad™ key
pad.

Blower Motor Thermal Contact The blower motor is

equipped with a contact that will open if the blower motor

Figure A-4 – Low Water

Safety Float Switch

temperature exceeds a safe operating level. If this contact

Appendix A A-10

Drain

Low Water

Safety Float

PGC, Inc 500-1000 CFM Air Handler May 2006

opens, the air handler will shut down. The SmartPad™ user interface will indicate “FAN TEMP
FAULT SET”. The thermostat will automatically reset when the blower motor tempeature returns
to a safe operating level. After the thermostat has reset, the SmartPad™ user interface will
indicate “FAN TEMP FAULT CLEAR”, and the system may be restarted by pressing the

Standby key on the SmartPad™ key pad.

Motor Starter Protector If a motor starter protector (MSP) trips, that component will not

operate. The starter must be reset by turning it to the Off position and then to the On position.
MSPs are used by the process blower, pump, and compressor.

Manual motor
starters in on,
off and tripped
positions

On Off Tripped

Figure A-5 – Motor Starter Protector (MSP)

Appendix A A-11