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Operation Manual
D
–EOMWC00A07-16_02EN
8.3
Circuit Status
The displayed circuit status is determined by the conditions in the following table:
Enum
Status
Conditions
0
Off:Ready
Circuit is ready to start when needed.
1
Off:Stage Up Delay
Circuit is off and cannot start due to stage up delay.
2
Off:Cycle Timer
Circuit is off and cannot start due to active cycle timer.
3
Off:Keypad Disable
Circuit is off and cannot start due to keypad disable.
4
Off:Circuit Switch
Circuit is off and circuit switch is off.
5
Off:Oil Heating
Circuit is off and Discharge Temperature
– Oil Saturated Temperature
at gas pressure <= 5°C.
6
Off:Alarm
Circuit is off and cannot start due to active circuit alarm.
7
Off:Test Mode
Circuit is in test mode.
8
EXV Preopen
Circuit is in preopen state.
9
Run:Pumpdown
Circuit is in pumpdown state.
10
Run:Normal
Circuit is in run state and running normally.
11
Run:Disc SH Low
Circuit is running and cannot load due to low discharge superheat.
12
Run:Evap Press Low
Circuit is running and cannot load due to low evaporator pressure.
13
Run:Cond Press High
Circuit is running and cannot load due to high condenser pressure.
8.4
Compressor Control
The compressor will run only when the circuit is in a run or pumpdown state. This means the compressor should not be
running any time the circuit is off or during preopening the EXV.
Cycle Timers
A minimum time between starts of the compressor and a minimum time between shutdown and start of the compressor
will be enforced. The time values are set by global circuit set points.
These cycle timers are enforced even through cycling of power to the chiller.
These timers may be cleared via a setting on the controller.
Compressor Run Timer
When a compressor starts, a timer will start and run as long as the compressor runs. This timer is used in the alarm log.
Compressor Capacity Control
After starting, the compressor will be unloaded to the minimum physical capacity and no attempt to increase compressor
capacity is made until the differential between evaporator pressure and oil pressure meets a minimum value.
After the minimum differential pressure is met, compressor capacity is controlled to 25%.
Compressor capacity will always be limited to a minimum of 25% while it is running, except for the time after compressor
start when the differential pressure is being built and except when changes to capacity are performed as needed to meet
unit capacity requirements (see unit capacity control section).
Capacity will not be increased above 25% until discharge superheat has been at least 12°C for a time of at least 30
seconds.
Manual capacity control
The capacity of the compressor can be controlled manually. Manual capacity control is enabled via a set point with choices
of auto or manual. Another set point allows setting the compressor capacity from 25% to 100%.
The compressor capacity is controlled to the manual capacity set point. Changes will be made at a rate equal to the
maximum rate that allows stable circuit operation.
Capacity control reverts back to automatic control if either:
•
the circuit shuts down for any reason
•
capacity control has been set to manual for four hours
Slide Control Solenoids (Asymmetric compressors)
This section applies to the following compressor models (asymmetric):
