Zone
Zone
SECTION 2: SEQUENCE OF OPERATIONS
Main Chiller Controller Technical Guide
22
Compressor Circuit Module Operation
Compressor Circuit Module
The Compressor Circuit Module performs the following functions:
•
Controls the operation of the compressor via
communications with the compressor control
board.
•
Manages the isolation valve.
•
Manages the load balance/startup bypass valve.
•
Communicates with and manages operation of the
Economizer/sub-cooling module.
• Communicates with and controls its associated
compressor via Modbus from the Modbus Master
port.
Points of Information and Control
The Compressor Circuit Module provides the following critical
points of information (beyond general status) to the Main Chiller
Controller via E-BUS (Modbus):
Commands
Compressor-Run
– This is a binary condition to run or stop
the compressor operation. This condition can be overridden by
the Disable Binary Input; if the input is active, the Compressor-
Run is overridden to indicate a stop condition.
Compressor-Demand
– This is a value provided to drive the
demand of the compressor. This should be a 0-100% value, with
0% = compressor minimum capacity and 100% = compressor
maximum capacity.
Status
Startup-Status
– This is a binary indication that this board
has completed all steps required for complete startup, including
all valve positioning operations.
Running-Status
– This value should indicate if the
compressor is running at, beyond, or below the demand.
Fault-Status
– This value should indicate any faults in the
compressor or within this module, including indication that the
Disable binary input is active.
Shutdown-Status
– This is a binary indication that the
board has completed all steps required for complete shutdown,
including all valve positioning operations.
Sequence
The sequence consists of several sub-sequences:
•
Load Balance/Startup Bypass Valve
• Isolation Valve
• Compressor Operation
Load Balance/Startup Valve Control
In the Off state, this valve shall be maintained closed.
Startup
1. When Compressor-Run is activated, wait a settable
delay.
2. Open the valve fully at the maximum operating rate.
3. Wait for the compressor control startup sequence to
complete.
4. Close this valve at a settable rate.
5. Startup is completed when the valve is fully closed.
Shutdown
1. Prior to Compressor-Run deactivation, open valve
to 100% (6386 steps).
2. Wait 20 seconds before deactivating the
compressor.
3. Once the Compressor is confi rmed off , close the
valve.
Isolation Valve Control
Startup
1. When Compressor-Run is activated, open this valve
immediately.
2. Wait a settable delay before considering startup
complete (default is 90 seconds).
Shutdown
1. When Compressor-Run is deactivated and the
compressor control sequence has completed, close
this valve.
2. Wait a settable delay as used in opening and
consider shutdown complete.
