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Operation Manual
D
–EOMWC00A07-16_02EN
Figure 6, Circuit Sequence of Operation
Is circuit commanded to
start?
Is circuit commanded to
shut down?
Pumpdown circuit
Yes
Yes
No
Unit power up
Circuit is in Off state
No
Run circuit
When the circuit begins to run, the compressor will be started and the EXV, fans,
and other devices will be controlled as needed. The normal circuit status at this
time will be
Run
.
When the circuit is commanded to shut down, a normal shut down of the circuit will
be performed. The circuit status during this time will be
Run:Pumpdown
. After
the shut down is completed, the circuit status will normally be
Off:Cycle Timer
initially
.
When the circuit is in the Off state the EXV is closed, compressor is off, and all fans
are off.
Is circuit is enabled to
start?
Yes
No
The circuit must be enabled before it can run. It may be disabled for several
reasons. When the circuit switch is off, the status will be
Off:Circuit Switch
.
If the BAS has disabled the circuit, the status will be
Off:BAS Disable
. If the circuit
has an active stop alarm then the status will be
Off:Cir Alarm
. If the circuit has
been disabled via the circuit mode set point, the status will be
Off:Cir Mode
Disable
.
Is compressor oil sump
ready?
Yes
No
If the compressor is not ready due to refrigerant in the oil, the circuit cannot start.
The circuit status will be
Off:Refr In Oil.
Circuit is ready to start
If the compressor is ready to start when needed, the circuit status will be
Off:Ready
.
Are compressor cycle
timers active?
No
Yes
A minimum time must pass between the previous start and stop of a compressor
and the next start. If this time has not passed, a cycle timer will be active and the
circuit status will be
Off:Cycle Timer
.
AWS Sequence of Operation - Circuits
