64
AGZ 026B through 130B
IOMM AGZ-5
High Condenser Pressure
If the discharge pressure rises above the High Condenser Pressure Unload setpoint, and
more than one compressor on the circuit is running, the circuit will stage down. One
compressor will shutdown as soon as the pressure rises above the unload setpoint, and
if two remain running, then one more will shut down 10 seconds later, if the pressure is
still above the unload setpoint. No stage up will be allowed on the circuit until the
condenser pressure drops to the unload setpoint, less 100 psi, and the outdoor ambient
temperature drops 5 degrees F.
Low Ambient Lockout
If the OAT drops below the low ambient lockout setpoint, then all running circuits will
do a normal stop. Once the lockout has been triggered, no compressors will start until
the OAT rises to the lockout setpoint plus 5 degrees F.
High Ambient Limit
On units not configured with multi-point power connections, the maximum load amps
could be exceeded at high ambient temperatures. If all circuit 1 compressors are
running or all but one compressor on circuit 1, power connection is single point, and
the OAT is greater than 116
°
F, circuit 2 is limited to running all but one compressor.
The circuit 2 status will indicate if this is the case. This action will allow the unit to
operate at higher temperatures than 116
°
F.
Unit Capacity Overrides
The following conditions override the automatic capacity control when the chiller is in
COOL mode only.
Demand Limit
The maximum unit capacity can be limited by a 4-to-20 mA signal on the Demand
Limit analog input. This function is only enabled if the Demand Limit setpoint is set to
ON. The maximum unit capacity stage is determined as shown in the following graphs:
1
2
3
4
0.0
25.0
50.0
100.0
75.0
Max
Stage
3
4
5
6
0
16.7
66.7
83.3
50.0
Limit Signal (%)
Max
Stage
33.3
100.0
2
1
0
Limit Signal (%)
Limit Signal vs. Max Stage
(with 4 compressors)
Limit Signal vs. Max Stage
(with 6 compressors)
Summary of Contents for AGZ026BS
Page 103: ...IOMM AGZ 5 AGZ 026B through 130B 103...
Page 104: ...104 AGZ 026B through 130B IOMM AGZ 5...
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