www.DaikinApplied.com 57 IOM 1322 • WATER-COOLED SCROLL COMPRESSOR
No Pressure Change at Start
Alarm description (as shown on screen):
NoPressChgAtStartN
Trigger: Circuit has failed twice on a No Pressure Change
at Start Condition. A No Pressure Change at Start Condition
indicates that after the start of the rst compressor on the
circuit, at least a 1 psi drop in evaporator pressure OR a 1
psi increase in condenser pressure has not occurred after 15
seconds of compressor operation.
Action Taken: Rapid stop circuit
Reset: This alarm can be cleared manually via the keypad.
Alarm description (as shown on screen):
No EXB comm CP1
Trigger: CP1 does not have communication with either EXB1
for 60 seconds after power up. This alarm will only occur if 10
Fan , evaporator pump #2, or condenser pump #2 operation
is selected. After communication is established, when
communication is lost to either EXB an immediate shutdown
occurs.
Action Taken: Rapid stop all circuits
Reset: Auto clear when EXB1 is communicating with CP1.
Alarm Log
An alarm log stores the last 25 alarms and/or events to occur.
When an alarm or event occurs, it is put into the rst slot in the
alarm log and all others are moved down one, dropping the last
entry. In the alarm log, the date and time the alarm occurred
are stored, as well as a list of other parameters. These
parameters include compressor states, evaporator pressure,
condenser pressure, number of fans on, OAT, and evaporator
LWT.
Active Alarms
When an alarm occurs, it appears in the active alarm list. The
active alarm list holds a record of all active alarms, which
includes the date and time each occurred.
Clearing Alarms
A password is NOT required to clear an active alarm. Active
alarms must be cleared at the unit controller. To clear active
alarms scroll down to the end of the Active Alarm list press
Enter to clear all active alarms. If the user attempts to clear an
alarm while the alarm condition still exists, a new alarm will be
generated immediately.
Limit Events
The following events do not cause a rapid stop but limit
operation of the chiller in some way as described in the Action
Taken. All limit events do NOT appear in the Active Alarm
window and are NOT logged in the Alarm Log
Low Evaporator Pressure - Hold
Event description (as shown on screen):
Evap Press Low HoldN
Trigger:
This event is triggered if all of the following are true:
• Circuit state = Run
• Circuit is not currently in a low OAT start
• Has been at least 30 seconds since a compressor has
started on the circuit.
• Evaporator pressure <= Low Evaporator Pressure - Hold
set point
Action Taken: Inhibit staging on of additional compressors on
the circuit.
Reset: While still running, the event will be reset if evaporator
pressure > (Low Evaporator Pressure - Hold set point + 8psi
for R134a or 13 psi for R410A). The event is also reset if the
circuit state is no longer run.
Low Evaporator Pressure - Unload
Event description (as shown on screen):
EvapPressLow Unload N
Trigger:
This event is triggered if all of the following are true:
• Circuit state = Run
• More than one compressor is running on the circuit
• Circuit is not currently in a low OAT start
• Has been at least 30 seconds since a compressor has
started on the circuit.
• Evaporator pressure <= Low Evaporator Pressure -
Unload set point for a time greater than halfof the current
freezestat time
Action Taken: Stage o one compressor on the circuit every
10 seconds, except the last one.
Reset: While still running, the event will be reset if evaporator
pressure > (Low Evaporator Pressure - Hold set point + 8psi
for R134a or 13 psi for R410A). The event is also reset if the
circuit state is no longer run.
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