McQuay AGZ026BS, Installation, Operation And Maintenance Manual

Page: 59 / 106

IOMM AGZ-5 AGZ 026B through 130B 59
Table 40, Shutdown Alarms
Description Occurs When:
Action
Taken
Reset
No Evaporator Water Flow
Evap Pump State = RUN AND Evap Flow Digital
Input = No Flow for time > Evap Flow Proof SP
Rapid Stop
Unit
Evap flow switch
closes
Low Evaporator Pressure
Evaporator Press < Low Evap Pressure SP for
time > Low Evap Pressure Delay SP
Rapid Stop
Circuit
manual
High Condenser Pressure Condenser Press > High Condenser Pressure SP
Rapid Stop
Circuit
manual
Mechanical High Condenser
Pressure/Motor Protect
Digital Input = Off
On Power Up: Delay 150 Sec. before checking
Rapid Stop
Circuit
manual
Phase Voltage Protection (opt.)
If Phase Voltage Protection = Y, Then
Digital Input Off= Phase/Voltage Problem
Rapid Stop
Circuit
Phase/Voltage
Input returns to
normal
Ground Fault Protection (opt.)
If Phase Voltage Protection = Y, Then
Digital Input Off= Phase/Voltage Problem
Rapid Stop
Circuit
manual
Re-Start Fault Re-Start = Third Time
Rapid Stop
Circuit
manual
Evap. Freeze Protect
Evap LWT < Evaporator Freeze SP AND Unit state
= enable
Rapid Stop
Unit
manual
Leaving Evap. Water Temp.
Sensor Fault
Sensor shorted or open
Normal Stop
Unit
manual
Evaporator Pressure Sensor
Fault
Sensor shorted or open
Rapid Stop
Circuit
manual
Condenser Pressure Sensor
Fault
Sensor shorted or open
Rapid Stop
Circuit
manual
Outside Ambient Temp. Sensor
Fault
Sensor shorted or open
Normal Stop
Unit
manual
NOTE: SP=SetPoint
Events (Limit Alarms)
The following events limit the operation of the chiller in some way, as described in the Action
Taken column. These events are auto-clearing based on reaching the conditions in the reset
column.
Table 41, Limit Alarms
Description Occurs When: Action Taken Reset
Condenser Pressure Stage
Down Pressure > High Condenser Stage Down
Setpoint Shutoff
Stage #2 Condenser Press drops
below (SP – 100psi)
Low Ambient Lockout Any compressor is running AND Outside
Ambient < Low Amb Lockout SP Shutoff Stages #1
& #2 Outside Ambient > Low
Amb Lockout
(SP + 5ºF)
Low Evaporator Pressure –
Hold Pressure < Low Evap Pressure–Hold
Setpoint Hold @
Stage 1 Evap Press rises above
(SP + 8psi)
Low Evaporator Pressure –
Unload Pressure < Low Evap Pressure–Unload
Setpoint Shutoff
Stage 2 Evap Press rises above
(SP + 10 psi)
NOTE: SP = Setpoint
Logging
When an alarm or event occurs, the description, date, and time are stored in the active alarm
buffer corresponding to that alarm, viewed on the Alarm Active screens, and also in the alarm
history buffer, viewed on the Alarm Log screens. The active alarm buffers hold a record of all
current alarms. The active alarms can be cleared by pressing the Enter key when the end of the
list has been reached by scrolling. Active alarms may only be cleared if the appropriate
password level is active.
A separate alarm log stores the last 25 alarms and events that occur. When an alarm or event
occurs, it is put into the first slot in the alarm log, and all others are moved down one, dropping
the last entry. The date and time of the occurrence are stored in the alarm log, as well as the
unit state. If the alarm is a circuit alarm, then the circuit state, refrigerant pressures and
temperatures, and number of fans on are also stored. The parameters may be accessed by
scrolling the last line on the alarm log screen (similar to a setpoint).