OM AGSD-1
53
Low Evaporator Pressure
Alarm description (as shown on screen):
Evap Press Low N
Trigger:
[Freezestat trip AND Compressor State = Run AND Low OAT Start not active]
OR Evaporator Press < -10 psi
Freezestat logic allows the circuit to run for varying times at low pressures. The lower the
pressure, the shorter the time the compressor can run. This time is calculated as follows:
Freeze error
= Low Evaporator Pressure Unload – Evaporator Pressure
Freeze time
= 70 – 6.25 x freeze error, limited to a range of 20-70 seconds
When the evaporator pressure goes below the Low Evaporator Pressure Unload setpoint, a
timer starts. If this timer exceeds the freeze time, then a freezestat trip occurs. If the
evaporator pressure rises to the unload setpoint or higher, and the freeze time has not been
exceeded, the timer will reset.
Action Taken:
Rapid stop circuit
Reset:
This alarm can be cleared manually via the Unit Controller keypad if the evaporator
pressure is above –10 psi.
Evaporator Pressure Switch Fault
Alarm description (as shown on screen):
Mech Low Pressure Sw N
Trigger:
Mechanical Low Pressure switch input is low and Remote Evap setpoint = Yes
Action Taken:
Rapid stop circuit
Reset:
This alarm can be cleared manually via the Unit Controller keypad if the MLP
switch input is high.
High Lift Pressure
Alarm description (as shown on screen):
Lift Pressure High N
Trigger:
Condenser Saturated Temperature > Max Saturated Condenser Value for time >
High Lift Delay setpoint
Action Taken:
Rapid stop circuit
Reset:
This alarm can be cleared manually via the Unit Controller keypad
Mechanical High Pressure
Alarm description (as shown on screen):
Mech High Pressure Sw N
Trigger:
Mechanical High Pressure switch input is low
Action Taken:
Rapid stop circuit
Reset:
This alarm can be cleared manually via the Unit Controller keypad if the MHP
switch input is high.
High Discharge Temperature
Alarm description (as shown on screen):
Disc Temp High N
Trigger:
Discharge Temperature > High Discharge Temperature setpoint AND compressor
is running
Action Taken:
Rapid stop circuit
Reset:
This alarm can be cleared manually via the Unit Controller keypad.
Summary of Contents for AGS 225D
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