ULTIMA 2000
Chillers
Chillers
Installation & Maintenance Manual : 903-099 IM E 05/00
23
Controls
ADJUSTING CUSTOMER CONTROL SETTINGS
Software Knobs
The following factory set unit operating and alarms settings may be viewed and adjusted:
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Knob Title & Sequence
Factory Set
Range
•
Restart Delay
10 seconds
10
- 120
•
Supply Water Temperature Setpoint
7°C
-7
- 20
•
Unit Temperature Difference
5°C
4
-
8
•
Supply Water Temperature Low Limit
3°C
-10
- 20
•
Low Suction Level
3.2 BarG
2.5
- 10
•
Compressor Loading Delay
90 seconds
10
- 120
•
Head Pressure Control Setpoint
17 BarG
10
- 25
•
Head Pressure Control Stage Differential
18%
0
- 18
•
Head Pressure Control Proportional Gain
-20
-100
-
0
•
Head Pressure Control Integral Term
5
0
- 100
•
Unit Loading Stage 1 to 8
Refer to Airedale
0
- 100
Restart Delay
The Restart Delay
is the delay before the controller energises any of its controlled outputs
after a power failure. In order not to induce large currents on multiple unit systems start-
up, the restart delay may be adjusted to different values within each chiller controller.
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Supply Water
Temperature Setpoint
The controller uses the Supply Water Temperature Setpoint and the unit temperature
difference setting to calculate the individual cooling stage setpoints, i.e. the temperatures
at which each of the compressor stages are activated or de-activated.
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The setpoint is utilised for both Constant and Variable Supply Water Temperature
controls schemes.
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Unit Temperature
Difference
The Unit Temperature Difference
entered should be equal to the temperature difference
between supply and return water when the unit is operating at maximum cooling capacity.
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Supply Water
Temperature Low Limit
If the Supply Water Temperature
falls below the low limit value set by this knob the
controller will generate a manual reset alarm and de-activate all controller outputs.
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Due to the application of low temperature glycol systems, it is possible to adjust this
temperature below 0°C.
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CAUTION
Under no circumstances should the low temperature value be adjusted to within
less than 3°C of the freezing temperature of the fluid being used.
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Low Suction Level
When the suction pressure sensor value falls below the value set by the Low Suction
Level for a period exceeding 1 minute or 3 minutes on compressor start-up, an audio-
visual alarm will be generated at the display and the relevant compressor will be de-
activated.
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Compressor Loading
Delay
If, after a cooling stage has been initialised there is still a cooling demand; the controller
will inhibit the next cooling stage output until the duration in this knob setting has elapsed.
If the cooling demand is still required after this delay period has elapsed the controller will
initialise another cooling stage.
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Head Pressure Control
Setpoint
The head pressure of each circuit will be controlled to the value entered in this knob.
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Head Pressure Control
Stage Differential
When the stepped head pressure control option is selected the value in this knob is used
to calculate the actual on and off switching points for each condenser fan stage.
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Head Pressure Control -
Gain & Integral Term
The Gain and Integral Term
are used together to calculate the head pressure control
output. The proportional gain value must be entered as a negative number.
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Unit Loading Stage 1 - 8
Factory set to suit the percentage loading of each cooling stage with respect to the unit
temperature difference.
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