CWC DIGICHEM-XP2 Instruction Manual

Instruction Manual

Cooling Water Treatment Controller

Model: DIGICHEM-XP2

Biocide A

Power
Bleed

Biocide B
Inhibitor
Alarm

Time & Date

UP

Main Menu

DOWN

Reset

ENTER

Water Treatment Controller

Comms

Supplied by:

Convergent Water Controls Pty Ltd

2/4 Huntley Street, PO Box 7058
Alexandria NSW 2015

t: [phone] w: cwc.com.au
f: [phone] e: [e-mail]

M1 ver 1.5

Fill in serial
number here

Ö

Refer to
back page

Manufacturer:

Convergent Water Controls Pty Ltd, Sydney Australia.

Note:

On-going product development at Convergent Water Controls may lead

to changes in the specifications of this product.

Warranty:

This product is guaranteed for a period of 12 months from installation

date or 18 months from Invoice date (whichever occurs first). The
warranty applies to manufacturing or component defects which may
cause the unit to malfunction under specified conditions. The guarantee
does not cover damage due to abuse, tampering or improper installation.

Disclaimer:

Convergent Water Controls will not be held liable for any consequential

damage or loss arising resulting from product malfunction.

TTaabbllee ooff CCoonntteennttss

1.

Introduction...........................................................................................................................7

2. Installation ............................................................................................................................7

2.1 Electrical Wiring...........................................................................................................................7

2.2 Conductivity Probe Installation & Maintenance...............................................................................8

3. Controller Functionality.........................................................................................................9

3.1 Menu Logic..................................................................................................................................9

3.2 Pushbuttons .............................................................................................................................. 10

3.3 LED Indication........................................................................................................................... 11

3.4 Comms Port............................................................................................................................... 12

4. Commissioning.....................................................................................................................13

4.1 Start-Up .................................................................................................................................... 13

4.2 Setting Time & Date................................................................................................................... 14

4.3 Calibration................................................................................................................................. 15

4.4 Testing Relay Outputs................................................................................................................ 18

4.5 Manual Dose.............................................................................................................................. 19

4.6 View Settings............................................................................................................................. 20

4.7 Factory Settings......................................................................................................................... 20

5. Programming Setup Menu...................................................................................................21

5.1 Set Units ................................................................................................................................... 23

5.2 Set Bleed Setpoint ..................................................................................................................... 23

5.3 Set Hysteresis............................................................................................................................ 24

5.4 Set Bleed Cycle..........................................................................................................................25

5.5 Alarm Parameters ...................................................................................................................... 26

5.5.1 High Conductivity Alarm....................................................................................................................27

5.5.2 Low Conductivity Alarm.....................................................................................................................27

5.5.3 No Flow Alarm..................................................................................................................................28

5.5.4 Delay On Alarm................................................................................................................................28

5.5.5 Bld Timer Alarm................................................................................................................................29

5.6 Inhibitor Setup........................................................................................................................... 29

5.7 Biocide Setup............................................................................................................................. 33

5.8 Pre-Bleed Setpoint ..................................................................................................................... 36

5.9 Bleed Lock-out Setpoint.............................................................................................................. 36

5.10 Auxiliary Output On Timer ........................................................................................................ 37

5.11 Flow Switch ............................................................................................................................. 39

5.12 Data Logging........................................................................................................................... 40

6. Factory Settings...................................................................................................................41

7. Specifications.......................................................................................................................42

8. Service & Technical Support................................................................................................43

1. Introduction

Designed for cooling tower water treatment, the DIGICHEM-XP2 electronic
controller incorporates the following key features:

• Conductivity bleed control

• Inhibitor pump dosing control

• Dual Biocide pump contro l (via 10 independent 28-day timer programs)

• Data logging

• Tower circulating/condenser pump override facility with delay-off timer

• High and Low Conductivity alarms with programmable delay-of f timer

2. Installation

Mount the DIGICHEM-XP2 on a flat vertical surface away from extreme heat,
humidity or areas where temperature variations are extreme, ideally at eye­level to allow good visibility of the LCD display. Also ensure that a 240VAC
mains power point is located nearby.

2.1 Electrical Wiring

CAUTION: If opening the controller, pull the lid away from the base slowly to

ensure you do not impose any strain on the interconnecting cable,
which easily unplugs from the motherboard.

Page 5 of 43

The diagrams below shows the connections to the DIGICHEM-XP2 controller
circuitry (release 1 & release 2).

L14

L13

L12

L11

L10

R4

R15

R14

R13

R5
R6

R3

R2

R1

FUSE

2A/250VAC

R20

R19

L9

L8

L7

L6

R10
R11
R12

R9

R8

R7

R18

R17

R16

Release 1

L6: Conductivity Probe PR+ (Brown or Red)
L7: Conductivity Probe PR- (Yellow)
L8: Conductivity Probe CM+ (Blue)
L9: Water Meter In
L10: Flow Switch In
L11: Flow Switch Common / Water Meter Common / Probe

Cable Screen (Grey)
L12 + L14: Alarm Relay N/O volt-free (10A/250VAC res)
L13 + L14: Alarm Relay N/C volt-free (10A/250VAC res)

R1: Mains Active 240VAC (power supply)
R2: Mains Neutral
R3: Auxiliary Continuous Active 240VAC (2A fused)
R4: Auxiliary Neutral
R5: Solenoid Valve Active 240VAC (2A fused)
R6: Solenoid Valve Neutral
R7: Inhibitor Pump Active 240VAC (2A fused)
R8: Inhibitor Pump Neutral
R9: Biocide ‘A’ Active 240VAC (2A fused)
R10: Biocide ‘A’ Neutral

Page 6 of 43

R11: Biocide ‘B’ Active 240VAC (2A fused)
R12: Biocide ‘B’ Neutral
R13 - R18: Common Earth
R19: Condenser Pump Relay common
R20: Condenser Pump Relay N/O volt-free (10A/250VAC res)

Fuse: 2A/250VAC (M205, 20mm x 5mm diameter)

Notes on Alarm Relay Contacts :

1. Alarm relay is energised (ie. L14 connected to L12) during normal
operation of the unit.

2. Alarm relay de-energises (ie. L14 connected to L13) when an alarm
condition is confirmed or when the unit loses power.

Notes on Flow Switch:

A flow switch with N/O or N/C volt-free contacts are required to be connected
to terminals L10 & L11 (not polarity sensitive). The flow switch logic is
programmable via the menu.

Page 7 of 43

L4

L13

L12

L11

L10

R4

R15

R14

R13

R5
R6

R3

R2

R1

FUSE

2A/250VAC

R20

R19

L9

L8

L7

L6

R10
R11
R12

R9

R8

R7

R18

R17

R16

L5

Release 2

L4: Conductivity Probe Cable Screen (Grey)
L5: Conductivity Probe PR+ (Brown or Red)
L6: Conductivity Probe PR- (Yellow)
L7: Conductivity Probe CM+ (Blue)
L8: Water Meter In
L9: Flow Switch In
L10: Flow Switch Common / Water Meter Common / Probe

Cable Screen (Grey)
L11 + L13: Alarm Relay N/O volt-free (10A/250VAC res)
L12 + L13: Alarm Relay N/C volt-free (10A/250VAC res)

R1: Mains Active 240VAC (power supply)
R2: Mains Neutral
R3: Auxiliary Continuous Active 240VAC (2A fused)
R4: Auxiliary Neutral
R5: Solenoid Valve Active 240VAC (2A fused)
R6: Solenoid Valve Neutral
R7: Inhibitor Pump Active 240VAC (2A fused)
R8: Inhibitor Pump Neutral
R9: Biocide ‘A’ Active 240VAC (2A fused)
R10: Biocide ‘A’ Neutral
R11: Biocide ‘B’ Active 240VAC (2A fused)

Page 8 of 43

R12: Biocide ‘B’ Neutral
R13 - R18: Common Earth
R19: Condenser Pump Relay common
R20: Condenser Pump Relay N/O volt-free (10A/250VAC res)

Fuse: 2A/250VAC (M205, 20mm x 5mm diameter)

Notes on Alarm Relay Contacts :

1. Alarm relay is energised (ie. L13 connected to L11) during normal
operation of the unit.

2. Alarm relay de-energises (ie. L13 connected to L12) when an alarm
condition is confirmed or when the unit loses power.

Notes on Flow Switch:

A flow switch with N/O or N/C volt-free contacts are required to be connected
to terminals L9 & L10 (not polarity sensitive). The flow switch logic is
programmable via the menu.

2.2 Conductivity Probe Installation & Maintenance

The probe is supplied screwed into a PVC Tee piece such that the electrode tips
are submerged in the water flowing through the manifold in which the tee is
usually fitted. The probe should be positioned with the black markers on the
probe aligned with the black markers on the manifold Tee. This ensures that
the 2 electrodes of the probe are positioned symmetrically with respect to the
direction of water flow. See the photograph and diagrams below:

DIRECTION

OF FLOW

Page 9 of 43

The probe’s electrodes should periodically be cleaned to maintain accurate TDS
measurements. The frequency of cleaning required will vary from one
application to another. In a new installation, it is recommended that the probe
be cleaned after 2 weeks of service.

To clean the probe, first unplug the probe lead and unscrew the probe from the
manifold. The probe can normally be cleaned using a cloth or paper towel.
Occasionally the probe’s carbon electrodes may be coated with substances
which requires more vigorous cleaning (this coating may not always be visible).
To clean a coated electrode, use a fine grit abrasive, such as emery paper.

After cleaning, apply more Teflon

®

tape to the probe thread and screw back
into the manifold. The controller should always be calibrated after probe
cleaning.

3. Controller Functionality

3.1 Menu Logic

The DIGICHEM-XP2 has an advanced but very user-friendly menu system:

• The menu structure is circular

• The relevant menu item, or programmed value flashes

• Up & Down arrow pushbuttons allow you to scroll through the menu items

and to increase/decrease programmed settings

• The MAIN MENU expands to several levels of SUB MENUS when pressing
ENTER on various menu items

• The LCD is backlit

The MAIN MENU of the controller is illustrated as follows (see next page):

Page 10 of 43

MANUAL DOSE

EXIT

SETUP MENU

FACTORY SETTINGS

TEST OUTPUTS

CALIBRATE

TIME & DATE

VIEW SETTINGS

995 TDS [1000]

Hold

To access
menu item
press

3.2 Pushbuttons

The DIGICHEM-XP2 has 3 pushbuttons which each have dual functions:

1. Scroll UP (Time & Date)

2. Scroll DOWN (Main Menu)

3. ENTER (Reset)

• The Scroll UP and DOWN pushbuttons allows you to scroll in both
directions in the circular menus. Once a menu item has been selected and
there is a value to program, the Scroll pushbuttons allow you to increase or
decrease the number programmed.

• The ENTER pushbutton allows you to ente r a part of the program that you
have selected. It also accepts any numbers programmed with the Scroll
pushbuttons.

Page 11 of 43

• If the Scroll UP (Time & Date) pushbutton is pressed momentarily in
NORMAL MODE (explained in section 4.1), the time and date is displayed.
To revert back to NORMAL MODE, press the pushbutton momentarily again.

The time and date is displayed as follows:

NOTE:
The Time & Date is programmable, but the Week No is automatically set.
Hence, if you have multiple controllers in the field, the Week No will be
the same on all (assuming the Time & Date are programmed correctly).

• To get into the me nus of the DIGICHEM-XP2, hold down the Scroll DOWN
(Main Menu) pushbutton. The display will count down until you access the
menus.

• If you wish to cancel an alarm or any timers activated, press and hold the
ENTER (Reset) pushbutton until the display says:

3.3 LED Indication

There are 6 LEDs on the front face of the DIGICHEM-XP2:

• Power (green): illuminates continuously when power is applied to the

controller

• Bleed (amber): illuminates continuously when power is applied to the

solenoid output of the controller. If the solenoid output
is suspended due to a pause in the bleed cycle, the LED
will flash on and off.

• Biocide A (amber): illuminates continuously when power is applied to the

Biocide A output of the controller.

• Biocide B (amber): illuminates continuously when power is applied to the

Biocide B output of the controller.

• Inhibitor (amber): illuminates continuously when power is applied to the

Inhibitor output of the controller. If the Inhibitor output
is suspended due to no flow, the LED will flash on and
off during the ON cycle.

Page 12 of 43

• Alarm (red): illuminates when the alarm relay switches. If the alarm

delay is timing before the alarm condition is confirmed,
the LED will flash on and off.

3.4 Comms Port

There is a Comms port on the front panel of the controller next to the LCD.
This is used to download data from the controller, and can also used to upload
new software versions should they be required.

The data is downloaded via the Comms port on the front panel of the
controller. An optional cable is required, P/N SP-XP2-COMCABLE-1, to perform
a direct download to a pc or laptop.

Page 13 of 43

4. Commissioning

CAUTION: Refer to previous section before reading this section

4.1 Start-Up

Power up the controller after installation. After a start-up sequence, the
controller automatically goes into NORMAL MODE. The display should read the
measured conductivity as well as the conductivity Setpoint within square
brackets (which alternates with the temperature as measured by the
conductivity probe), as follows:

NOTE: An asterisk ‘*’ flashes on the screen when the controller receives a
pulse from an optional water meter (Software version 2.0 and above). The
asterisk '*' may appear on the LHS of the display or within the square brackets
just before the Conductivity Setpoint or Temperature.

Other information that you may see on the display, which alternates with the
display above:

• When an alarm is reported, the actual alarm message will be periodically

displayed, e.g.

• When a flow switch is connected to the controller, each output is

suspended when there is no flow past the flow switch, if the output is
selected via the Flow Switch Menu.

Page 14 of 43

4.2 Setting Time & Date

Main Menu > TIME & DATE

TIME: 10:30

TIME: 11:00

TIME: 10:00

DATE: 1 Jan 2006

DATE: 2 Jan 2006

DATE: 2 Nov 2006

TIME & DATE

Press or to change day

then

Press or to change month

Press or to change year

Example: Setting time & date to 10:30 on 2 Nov 2006

NOTE: The Week No will be automatically set

Page 15 of 43

4.3 Calibration

IMPORTANT: Select the display in either µS or TDS before proceeding.

(Refer section 5.1)

Calibrating the SLOPE

Main Menu > CALIBRATE

Take a sample of water from the sample valve on the manifold and
measure the conductivity with a hand-held conductivity meter.
Alternatively, insert the Conductivity probe in a buffer solution of known
conductivity. Should the conductivity readout on the display differ from
the sample taken, calibrate the controller as follows:

Adjust the current reading via the Calibration Menu to the desired
reading.

Page 16 of 43

Calibrating the ZERO

The zero is factory set so should not require calibration. However, if the
display reads above zero with the conductivity probe disconnected,
recalibrate the zero as follows:

1. Remove the probe from the manifold.

2. Dry the electrodes of the probe, so that there is zero (or minimal)
conductivity between the electrodes.

3. Wait until the reading on the LCD is stable. If the reading does not
settle to exactly 0, wait until it does not drop any further.

4. Go into the Calibrate Menu and set the Zero Calibration (see below).

5. Screw the probe back into the manifold.

6. Perform the SLOPE calibration again.

Page 17 of 43

Resetting the CALIBRATION

If you inadvertently calibrate the zero and/or slope to the incorrect
values, and you cannot recover by repeating the normal calibration
procedure, then you can reset the calibration and start again.

Page 18 of 43

4.4 Testing Relay Outputs

Main Menu > TEST OUTPUTS

Bleed O/P[OFF]

TEST OUTPUTS

BIO ‘A’ O/P [OFF]

Press or to turn ON

AUX. O/P [OFF]

ALARM O/P [OFF]

BIO ‘B’ O/P [OFF]

INHIBTR O/P [OFF]

Press or to turn ON

Press or to turn ON

Press or to turn ON

Press or to turn ON

Press or to turn ON

When any of the Outputs is activated, the respective Output LED illuminates
and the Output relay switches, putting 240VAC power onto the output terminal,
which activates the pump or solenoid valve wired to it.

When the Alarm Output is activated, the red Alarm LED illuminates and the
relay de-energises, switching the Common from the Normally Open Contact to
the Normally Closed contact of the Alarm relay.

NOTES:

1. If any output is activated manually without reverting back to the de­activated state, the controller will automatically turn the output off 2
minutes after no pushbutton activity.

2. If you wish to drive an output for longer than 2 minutes, activate the
MANUAL DOSE function within the MAIN MENU

3. The outputs should all switch on when tested, regardless of the flow
condition.

4. Do not switch the Aux O/P On relay rapidly ON and OFF, if powering the
condenser pump of the cooling tower.

Page 19 of 43

4.5 Manual Dose

Main Menu > MANUAL DOSE

To perform an unattended slug dose of chemical, simply program the dose time
(up to 99 minutes, in 1 minute increments) as follows:

Note: The pump will not dose if there is no flow

To cancel a manual dose, press and hold the ENTER (Reset)
pushbutton

Page 20 of 43

4.6 View Settings

Main Menu > VIEW SETTINGS

To view all the settings you have programmed into the controller without going
into the menus themselves, you can simply scroll up and down to view them
all:

HYSTERESIS 10%

Display: [TDS]

SETPOINT: 1000

ID: 0620-65535

10 P00h00 L00h00

VIEW SETTINGS

Press at any point to escape

4.7 Factory Settings

Main Menu > FACTORY SETTINGS

CAUTION:

• Enter this part of the prog r a m ONLY if you wish to erase your program
settings.

• The default settings (listed in Section 6 of this manual) most likely will not
suit your application, so it will be necessary to reprogram the controller
with your desired settings.

• This menu gives the option of resetting the calibration as well.

Page 21 of 43

CONFIRM? [NO ]

RESET? [NO ]

RESET? [YES]

CONFIRM? [YES]

RESET CAL? [NO ]

RESET CAL? [YES]

FACTORY SETTINGS

Press to escape

Press to escape

Press to reset unit to Factory Settings
(most recent Calibration NOT reset)

Press to reset unit to Factory Settings
and to reset Calibration to Factory default

5. Programming Setup Menu

Main Menu > SETUP MENU

IMPORTANT:

• Once settings are changed, it is necessary to exit the SETUP MENU in order
to save your settings.

• Setup Menu Structure illustrated as follows:

Page 22 of 43

HYSTERESIS

PRE-BLD SETPOINT

UNITS

BIOCIDE SETUP

BLEED SETPOINT

BLEED CYCLE

ALARM PARAMETERS

INHIBITOR SETUP

FLOW SWITCH

LOCKOUT SETPOINT

AUX O/P ON TIMER

SETUP MENU

You will be prompted to save any changed settings

To access
menu item
press

Setup Menu

DATA LOGGING

EXIT SETUP

Page 23 of 43

5.1 Set Units

Main Menu > SETUP MENU > UNITS

Conductivity can be displayed in either:

• TDS (Total Diss olved Solids), or

• μS (Microsiemens)

Note: The displayed units should be selected before performing any

calibration or programming of the unit.

5.2 Set Bleed Setpoint

Main Menu > SETUP MENU > BLEED SETPOINT

SETPOINT: 0950

BLEED SETPOINT

SETPOINT: 1050

SETPOINT: 1050

SETPOINT: 1000

Example: Increasing setpoint from 950 TDS to 1000 TDS

The Bleed Setpoint is the desired conductivity value of the process (displayed
in TDS or μS). When a solenoid valve is connected to the bleed output, the

Page 24 of 43

valve opens when the conductivity rises above the setpoint. When this occurs,
the tower water is flushed to drain and fresh make-up water dilutes the
system, thus lowering the conductivity of the tower water. The valve shuts
when the conductivity drops to the hysteresis value (explained in the next
section). The cycle repeats.

5.3 Set Hysteresis

Main Menu > SETUP MENU > HYSTERESIS

HYSTERESIS 01%

HYSTERESIS

HYSTERESIS 04%

Example: Increasing Hysteresis from 1% to 4%

Hysteresis is the deadband between the two conductivity points at which the
solenoid valve opens and closes. The solenoid valve opens when the
conductivity rises above the programmed setpoint and shuts when it drops to a
level below the setpoint. This level is called Hysteresis and is a % of the
setpoint.

Page 25 of 43

5.4 Set Bleed Cycle

Main Menu > SETUP MENU > BLEED CYCLE

When the controller calls for bleed, the solenoid valve can be programmed to
bleed continuously or on a cycle until it reaches the Conductivity Setpoint. To
leave the Bleed Cycle in its disabled state, proceed to the next section. If you
wish to program a bleed cycle, then proceed as follows:

The menu asks for a Bleed Time and a Wait Time to be programmed. The Wait
Time follows the Bleed Time, and the cycle is repeated until the Setpoint minus
hysteresis is reached.

A bleed cycle can prevent excessive tower drainage in a very small system and
allows the make-up to efficiently mix with the cooling tower water.

The ability to cycle is also useful because it prevents flooding by slowing down
the bleed flow rate into a blocked drain.

The following diagram illustrates a bleed cycle programmed for a 10 second
bleed off followed by 40 second wait:

In the example above, the solenoid bleeds 10 seconds during every 50 second
cycle (ie 10+40), which equates to a 20% bleed cycle.

If you wish to have the control output continuously active during bleed (rather
than cycling ON and OFF), simply set the Bleed/Wait times to 00/00s

Note: If the conductivity is greater than 25% above the programmed

setpoint, then the controller automatically adjusts the ON/OFF
bleed cycle to bring it to setpoint more quickly.

Page 26 of 43

5.5 Alarm Parameters

Main Menu > SETUP MENU > ALARM PARAMETERS

NO FLOW ALARM

HIGH ALARM

LOW ALARM

DELAY ON ALARM

BLD TIMER ALARM

EXIT

ALARM PARAMETERS

To access
alarm menu item
press

The controller has 5 programmable alarm functions as outlined above. If any
of the alarms are activated and confirmed, the common alarm contact
switches, the red Alarm LED illuminates, and the Alarm message is displayed
on the LCD.

Page 27 of 43

5.5.1 High Conductivity Alarm

The High Conductivity Alarm is activated if the Conductivity rises above the
programmed setting, and automatically resets if the Conductivity drops
below the programmed setting again.

Main Menu > SETUP MENU > ALARM PARAMETERS > HIGH ALARM

HIGH ALARM

HIGH ALARM: 1400

HIGH ALARM: 0000

Example: Setting a High Alarm of 1450 TDS

HIGH ALARM: 1450

then

Note: A setting of 0000 means the High Alarm is disabled.

5.5.2 Low Conductivity Alarm

The Low Conductivity Alarm is activated if the Conductivity drops below the
programmed setting, and automatically resets if the Conductivity rises
above the programmed setting again.

Main Menu > SETUP MENU > ALARM PARAMETERS > LOW ALARM

Note: A setting of 0000 means the Low Alarm is disabled.

Page 28 of 43

5.5.3 No Flow Alarm

Main Menu > SETUP MENU > ALARM PARAMETERS > NO FLOW ALARM

If the No Flow Alarm is enabled, the Alarm will activate when there is no
flow detected by the optional flow switch. If the No Flow Alarm is left
disabled, then the Alarm is unaffected by a no-flow condition.

5.5.4 Delay On Alarm

Main Menu > SETUP MENU > ALARM PARAMETERS > DELAY ON ALARM

DELAY ON ALARM

TRIP DELAY: 0030s

TRIP DELAY: 0008s

then

Example: Setting alarm delay of 30 seconds

When an alarm condition is detected, eg High Conductivity Alarm, the relay
only trips immediately if the Trip Delay is set to 0 seconds. However, if
alarms do not become immediately critical, it is better to program a delay
on the alarm to prevent “nuisance trips”.

If a Trip Delay, eg. 120s, is programmed, the alarm relay will only trip if
the High Conductivity condition exists continuously for 120 seconds.
However, if the Conductivity drops to below the High Conductivity Alarm
level before the 120 seconds times out, the Alarm condition will reset.

Whilst the Trip Delay is timing, the red Alarm LED will flash. If the alarm
condition still exists after the time delay, the LED will illuminate
continuously until the alarm cancels, at which point, the LED goes off.

Page 29 of 43

5.5.5 Bld Timer Alarm

Main Menu > SETUP MENU > ALARM PARAMETERS > BLD TIMER ALARM

The Bld (Bleed) Timer Alarm is the maximum acceptable bleed time for the
system to reach the Setpoint. This alarm is designed to protect the system
from excessive bleeding in the event of a false reading from a faulty
Conductivity probe, or if the controller itself is faulty.

To leave the alarm in its disabled state, the programmed setting is 000m.
If the system Conductivity reaches the Setpoint within the programmed

time, the timer resets. However, if the timer times out before the
Conductivity reaches the Setpoint, the bleed solenoid switches off and
remains disabled until the unit is manually reset by holding down the Reset
pushbutton.

5.6 Inhibitor Setup

Main Menu > SETUP MENU > INHIBITOR SETUP
There are 4 Possible Inhibitor Feed Pump Modes to select from:

• Continuous on Bleed

• % of Time on Blee d

• % of Time on Flow (24 hrs/day) – [Note: Optional Flow Switch required]

• Water M e ter Pulse

Page 30 of 43

Inhib: [On Bleed]

INHIBITOR SETUP

Inhib: [24hr/day]

Inhib: [ Pulses]

*

*

*

* Press to access settings

Continuous on bleed:

Pump doses continuously when measured Conductivity > Setpoint,
regardless of any bleed cycle programmed.

% of Time on Bleed:

Pump doses on a duty cycle when measured Conductivity > Setpoint,
independent from any bleed cycle programmed. Duty cycle is repeating
ON and OFF times, eg ON=30sec, followed by OFF=30sec & repeating (ie.
50% duty cycle).

Main Menu > SETUP MENU > INHIBITOR SETUP

ON Period: 0000s

Inhib: [On Bleed]

OFF Period: 0000s

ON Period: 0010s

OFF Period: 0040s

Example: Setting a 10s on period followed by a 40s off period

then

then

Page 31 of 43

% of Time on Flow (24 hours/day):

Pump doses on a continuous duty cycle. Duty cycle is repeating ON and
OFF times, eg ON=20sec, followed by OFF=60sec & repeating (ie. 25%
duty cycle). If there is not continuous flow through the manifold at all
times, flow switch option AF04 should be fitted.

Main Menu > SETUP MENU > INHIBITOR SETUP

ON Period: 0000s

Inhib: [24hr/day]

OFF Period: 3600s

ON Period: 0060s

OFF Period: 3600s

Example: Setting a 60s on period followed by a 3600s
(i.e. 1 hr) off period

then

then

For any of the % of Time modes above, you can use the following table as a
guide to set your Inhibitor pump duty cycle:

Dosing Pump Turn-down required ON Period OFF Period

10% of maximum dose rate 0010s 0090s
20% of maximum dose rate 0020s 0080s
30% of maximum dose rate 0030s 0070s
40% of maximum dose rate 0040s 0060s
50% of maximum dose rate 0050s 0050s
60% of maximum dose rate 0060s 0040s
70% of maximum dose rate 0070s 0030s
80% of maximum dose rate 0080s 0020s
90% of maximum dose rate 0090s 0010s
100% of maximum dose rate 0000s 0000s

Page 32 of 43

Water Meter Pulse:

Pump doses proportional to pulses received from a water meter fitted in the
make-up line. The DIGICHEM-XP2 activates the pump for a set time once a
pre-determined number of pulses is counted, explained further in the following
example:

Water meter pulse rate = 1 pulse / litre
Desired concentration = 100 p.p.m.

[100 p.p.m. = 10ml chemical / 100 litres flow = 10ml chemical / 100 pulses]

Hence, we require the pump to dose 10ml every 100 pulses counted.

How long does the pump need to dose to deliver 10ml?

Pump dose rate = 1300ml/hr = 0.36ml/sec
Dose time = 10ml / 0.36ml/sec = 27.8 seconds (i.e. approx. 30 sec)

Set PULSE COUNT = 100
Set DOSE PERIOD = 30 seconds

In the example above, the pump doses for 30 seconds (i.e. programmed dose
time) every 100 litres of make-up water (i.e. programmed pulse count of 100).

Main Menu > SETUP MENU > INHIBITOR SETUP

Pulse Count 0100p

Inhib: [ Pulses]

Dose Period 0000s

Pulse Count 0100p

Dose Period 0030s

Example: Setting Inhibitor to dose for 30s every 100 pulses

from water meter

then

then

Notes: (v2.0 or later) An ‘*’ will be displayed on the LCD screen
momentarily for each water meter pulse received.

Page 33 of 43

5.7 Biocide Setup

Main Menu > SETUP MENU > BIOCIDE SETUP

Biocide is dosed according to 28 day timer programs set up by the user.
There are 10 independent programs which can be programmed to operate
daily, once per week, or on any number of days per week, fortnightly or once a
month. A typical biocide program, which will operate at the same time on the
specified days of the week, consists of 3 consecutive time durations:

1. Pre-bleed

2. Biocide Dosing

3. Bleed Lock-out

1. Pre-bleed

This reduces the system conductivity to a lower temporary setpoint (eg.
85% of setpoint) prior to biocide dosing in order to allow for a longer
Bleed Lock-out duration without the risk of entering scaling conditions.
Pre-bleed duration is programmable from 1 minute up to 23 hours.
(Note: The Pre-Bleed Setpoint of 85%, ie. Setpoint -15% is fully
programmable, and is explained further in section 5.8).

2. Biocide dosing

The biocide pump (Pump A or Pump B) doses chemical, typically into a
manifold. Dose duration is programmable from 1 minute up to 23
hours and commences immediately after Pre-Bleed. Bleed-off is
disabled (ie. locked out) during dosing provided the Bleed Lock-out
setpoint is not exceeded.

3. Bleed Lock-out

After biocide dosing, bleed-off continues to be disabled for the lock-out
duration, programmable from 1 minute up to 23 hours, provided the
Bleed Lock-out setpoint is not exceeded. (Note: The default Bleed Lock­out Setpoint of Setpoint +20% is fully programmable, and is explained
further in section 5.9).

By preventing bleed-off during and after biocide dosing, the system is ensured
of receiving maximum benefit from the dosed biocide, as no biocide will be lost
during this time via bleed-off. Furthermore, because the conductivity is
reduced during Pre-Bleed, the system has a longer retention period. As a
result, a highly effective “kill” is achieved without resulting in high scaling
conditions.

Each of the 10 Biocide Dosing programs can be set up to operate Biocide pump
A or Biocide pump B. In other words, the programs can be allocated in any
combination to either of the two biocide outputs, A and B.

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For instance, if pump A is set up in 6 programs, pump B can only have up to 4
programs controlling it. Not all of the programs need to be allocated. If only
two of the programs are required, then the other 8 will remain disabled. Pump
A and Pump B work totally independently and each program has its own START
TIME, followed by its own consecutive PRE-BLEED, BIOCIDE DOSING and
BLEED LOCK-OUT durations. However, biocide programs should not

overlap.

Main Menu > SETUP MENU > BIOCIDE SETUP

PROGRAM [01]

BIOCIDE SETUP

EXIT

PROGRAM [02]

PROGRAM [10]

* Press to access program settings

*

*

*

Main Menu > SETUP MENU > BIOCIDE SETUP > PROGRAM [02]

(see next page)

Page 35 of 43

Example: Setting a Biocide Dosing Program (i.e. 2) to take place in Week 2 and Week 4, on a

Monday beginning at 14:15. Biocide will be dosed for 30 minutes after a pre-bleed
time of 45 minutes, after which bleed lockout will occur for 4 hours.

Page 36 of 43

5.8 Pre-Bleed Setpoint

Main Menu > SETUP MENU > PRE-BLD SETPOINT

PreBLD: Setp – 15%

PRE-BLD SETPOINT

PreBLD: Setp – 10%

Example: Decreasing Pre-bleed Setpoint from Setpoint - 15% to Setpoint - 10%

In the example above, the Pre-Bleed setpoint is set as the Normal Conductivity
Setpoint less 10%. Hence, during the Pre-bleed time (ie. Immediately before
biocide dosing), the normal conductivity setpoint is reduced by 10%, and the
controller will try to maintain this reduced setpoint until biocide dosing
commences. The objective of pre-bleed is to allow for a longer Bleed Lock-out
duration without the risk of entering scaling conditions.

5.9 Bleed Lock-out Setpoint

Main Menu > SETUP MENU > LOCKOUT SETPOINT

Lock/O: Setp + 20%

LOCKOUT SETPOINT

Lock/O: Setp + 50%

Example: Increasing Lockout Setpoint from Setpoint + 20% to Setpoint + 50%

In the example above, the Lockout setpoint is set as the Normal Conductivity
Setpoint plus 50%. Hence, during Biocide Dosing and during the Lockout time
(ie. Immediately after biocide dosing), the normal conductivity setpoint is
increased by 50%, and the controller will try to maintain this increased setpoint
until the Lockout Period expires. By preventing bleed-off during and after
biocide dosing, the system is ensured of receiving maximum benefit from the
dosed biocide, as no biocide will be lost during this time via bleed-off.
Furthermore, because the conductivity is reduced during Pre-Bleed, the system
has a longer retention period. As a result, a highly effective “kill” is achieved
without resulting in high scaling conditions.

Page 37 of 43

5.10 Auxiliary Output On Timer

Main Menu > SETUP MENU > AUX O/P ON TIMER

Biocid dose + 000m

AUX O/P ON TIMER

Biocid dose + 015m

Example: Setting Auxiliary Output Timer to 15 minutes

Often when biocides are dosed into the manifold of the DIGICHEM-XP2
systems, the circulating/ condenser pump of the cooling tower is not running.
This can cause problems of clogging and corrosion in the manifold, as well as
biocide not being dosed into the cooling tower water.

The DIGICHEM-XP2 controller has an on-board relay contact (N/O) which can
be wired into the condenser pump contactor (see wiring diagram in section

2.1). The contact provided is a dry contact so can be connected in series with
the condenser pump contactor circuit, or any other circuit as required.
Alternatively, the relay contact can power the contactor by looping 240VAC
active to the common of the relay contact and connecting the N/O contact to
the coil of the contactor. Note: In this instance, the contactor must have a
240VAC coil and must be normally powered from the same 240VAC mains
circuit as the DIGICHEM-XP2.

When either biocide pump starts dosing, the N/O contact closes, powering the
contactor which in turn starts the condenser pump. The condenser pump will
continue to run while the biocide is dosing, as well as for a period of time after
biocide dosing. This ensures continuous water circulation and effective mixing
of the biocide chemical.

This time that the pump runs AFTER a biocide dose, is programmed here as the
Auxilliary Output ON Time.

IMPORTANT: If this feature is used, it is not recommended to switch the

condenser pump on and off rapidly using the output test
feature, explained in section 4.4

Page 38 of 43

The following is another example of a biocide program set to dose on a weekly
cycle:

Start time: 07:00
Pre-Bleed: 00h60m (ie. 07h00 to 08h00)
Dose for: 00h60m (ie. 08h00 to 09h00)
Bleed L/O: 04h00m (ie. 09h00 to 13h00)

Other Program Settings

Setpoint = 1000 TDS
Pre Bleed Setpoint = Setpoint – 13% (ie. 870 TDS)
Bleed Lock-out Setpoint = Setpoint + 50% (ie. 1500 TDS)
Program = 01
Pump = A
Auxiliary Output On Timer = 30m (i.e. delay off time after A dose)

Page 39 of 43

5.11 Flow Switch

Main Menu > SETUP MENU > FLOW SWITCH

If an optional flow switch (eg. AF04) is connected to the controller, any or all of
the outputs can be disabled when there is no flow. An output, when selected
via this menu for flow detection, will stop immediately if no flow is detected.
For example, when bleeding, the solenoid valve will close immediately if no
flow is detected.

There are 3 possible settings in the menu for the flow switch:

• DISABLE: All outputs activate if required, regardless of flow or no flow

• NORMAL: Enabled outputs activate if required, only if the flow switch

input is shorted

• REVERSE: Enabled outputs activate if required, only if the flow switch
input is open circuit

LOGIC: [DISABLE]

LOGIC: [REVERSE]

LOGIC: [NORMAL]

Press to disable

FLOW SWITCH

Press to select which outputs
are disabled by flow switch

Press to select which outputs
are disabled by flow switch

None, one, two, three or all four of the outputs can be selected to be disabled if
there is no flow. Typically, the Bleed output and Inhibitor output are disabled if
there is no flow and the Biocides dose during their programs regardless of the
flow status. However, either or both of the Biocide outputs can be set to be
disabled if there is no flow.

Page 40 of 43

Main Menu > SETUP MENU > FLOW SWITCH > LOGIC [NORMAL]

5.12 Data Logging

Main Menu > SETUP MENU > DATA LOGGING

The controller has the facility to log the following items at the pre-programmed
intervals:

• Date

• Time

• Conductivity reading (in TDS or μS )

• Temperature

• Percentage of time the Flow Switch was registering flow

• Percentage of time the Bleed Output was active

• Percentage of time the Inhibitor Pump was dosing

• Percentage of time the Bio cide A Pump was dosing

• Percentage of time the Bio cide B Pump was dosing

• Percentage of time the Co mmon Alarm was activated

Page 41 of 43

The pre-programmed intervals are 5, 10, 15, 30, 60, 120 or 240 minutes.
If the controller is set to log every 0 minutes, then logging is disabled.

Each logged entry takes up memory, so the longer the interval, the longer the
time can be between downloads. For example, the controller will have enough
memory to store data for 9.4 days for a log taken every 5 minutes, 56.8 days
for a log taken every 30 minutes, or for 455 days for a log taken every 240
minutes.

Once the memory is full, the data logger loses the oldest information first.
The data is downloaded via the Comms port on the front panel of the

controller. An optional cable is required, P/N SP-XP2-COMCABLE-1, to perform
a direct download to a pc or laptop.

6. Factory Settings

The default factory settings are outlined below. These are the settings
programmed when a manual Factory Reset is initiated via the menu.

Menu Setting/Item Default

Units TDS (ie ppm Total Dissolved Solids)
Bleed Setpoint 1000 ppm TDS
Hysteresis 3%
Bleed Cycle ON/OFF = 00s/00s (ie. Disabled)
High Conductivity Alarm 0000 ppm TDS (ie. Disabled)
Low Conductivity Alarm 0000 ppm TDS (ie. Disabled)
No Flow Alarm Enable? [No]
Delay on Alarm Trip Delay: 0008s
Bleed Timer Alarm Max Bleed: 000m (ie. Disabled)
Inhibitor Mode On bleed
Inhibitor Duty Cycle ON/OFF = 0050s/0050s (ie. On Bleed Only)
Biocide Programs All programs disabled
Pre-Bleed Setpoint Setpoint -15%
Bleed Lockout Setpoint Setpoint +20%
Aux O/P On Timer Biocide Dose + 000m
Flow Switch Logic Disabled (ie no flow switch fitted)
Outputs disabled on no flow * Bleed & Inhibitor
Data Logging LOG Every: 000m (ie. Logging disabled)

* only if flow switch fitted and flow switch logic enabled

Page 42 of 43

7. Specifications

Item Specification

Power Supply 220-240VAC, 50/60Hz
Power Consumption 10W max (with no loads on outputs)

Inputs Conductivity Probe (incl.)

Water meter volt-free contact (optional)
Flow switch (optional, code AF04)

Auxiliary Mains Output 240VAC continuous (2A fused)
Control Output 2A/250VAC (fused)
Alarm Relay Output N/O & N/C (10A/250VAC resistive)
Condenser Pump (Aux) Relay Output N/O (10A/250VAC resistive)

Optional Outputs 4-20mA (P/N AF09)

4-20mA plus events (P/N AF10)
4mA = 0 µS/TDS, 20mA = 5000 µS/TDS

Measured Conductivity Resolution 1µS / 1 ppm TDS
Accuracy 0.5% of measured range
Repeatability & drift 1.0% of measured range

Logged Items Controller Model, Software version, No of log

entries, Controller ID No, Date, Time,
Conductivity, Temperature, Flow %, Bleed %,
Inhibitor %, Biocide A %, Biocide B %, Alarm %

Data retention 100 years
Battery backup 1 year (approx)
Enclosure rating IP55
Operating Temperature 0 - 50°C

Page 43 of 43

8. Service & Technical Support

Important: Please note the serial number and product/system

part number before calling for assistance.

Note:

1. Controllers incorporated in a system, have the same serial
numbers as the system itself.

2. The First 6 digits of serial is the date of manufacture (yymmdd)

Company Pty Ltd

Street, Suburb, State Postcode
Tel: ( ) Fax: ( )
E-mail

Part No: DIGICHEM-Plus+
Description: Cooling Tower Controller
Serial No: 0804070613

220-240 VAC 50/60Hz 10W IP65

warranty void if l a b e l removed

N1665

Company details

Part number &
description of controller

Controller unique

Serial Number

Supply voltage &
fre

q

uency

Device power consumption

Enclosure rating

C-tick logo & registration
number

Example of Controller Info Label

(Adhered to Controller Enclosure)