Operating Manual
D-EOMCP00104-14_01EN
EWYD_BZ
33/35
No delay is introduced if the suction pressure falls below the low pressure alarm setpoint by an amount greater or equal to
1 bar. Five automatic reset alarms (both from transducers and switches) are managed in all modes (cooling, cooling glycol,
ice, heat pump). These alarms switch off the compressor without signalling (alarm relay is not activated). Only the sixth
will be a manual reset alarm.
The “Low suction pressure alarm” are disabled during prepurge cycles and during pumpdown.
At compressor startup (after the end of prepurge cycles) the “Low suction pressure alarm” are disabled if a low ambient
start has been recognized. A manual reset of the alarm are required to restart the unit.
•
Low oil pressure.
A “Low oil pressure alarm” will trip the compressor if the oil pressure remains below the following
thresholds by a time longer than an adjustable value during compressors running and at compressor startup
Suction pressure*1.1 + 1 bar at compressor minimum load
Suction pressure*1.5 + 1 bar at compressor full load
Interpolated values at compressor intermediate load
A manual reset of the alarm are required to restart the unit
•
High oil pressure difference.
A “High oil pressure difference alarm” will trip the compressor if the difference between
the discharge pressure and the oil pressure remains over an adjustable setpoint (default 2.5 bar) by a time longer than
an adjustable value. A manual reset of the alarm are required to restart the unit
•
Low pressure ratio.
A “Low pressure ration alarm” will trip the compressor if the pressure ratio remains below the
adjustable threshold at rated compressor load by a time longer than an adjustable value.A manual reset of the alar m
are required to restart the unit
•
Compressor Startup failure.
A “Failed transition or starter alarm” will trip the compressor if the transition/starter switch
remains open for more than 10 seconds from compressor start. A manual reset of the alarm are required to restart
the unit
•
Compressor overload or motor protection.
A “Compressor overload alarm” will trip the compressor if the overload
switch remains open for more than 5 seconds after the compressor start. A manual reset of the alarm are required to
restart the unit.
•
Slave board failure.
A “Unit xx off-line alarm” will trip slave compressors if the master board cannot communicate with
slave boards for a time longer than 30 seconds. A manual reset of the alarm are required to restart the unit
•
Master board failure or network communication.
A “Master off-line alarm” will trip the slave compressors if slave board
cannot communicate with master board for a time longer than 30 seconds.
•
Probe failure.
A “Probe failure” will trip the compressor if the reading of one among the following probes goes out of
probe allowable range for a time longer than ten seconds.
-
Oil Pressure probe
-
Low Pressure probe
-
Suction temperature probe
-
Discharge Temperature probe
-
Discharge Pressure probe
The control display will show the faulted probe identification
•
Auxiliaries signal failure.
The compressor is tripped if one among the following digital inputs is opened for a timer
greater than an adjustable value (default is 10 s).
-
Compressor phase monitor or Ground protection failure
-
Variable speed driver alarm
6.3 Other trips
Other trips may disable particular functions described in the following (e.g. heat recovery trips). The addition of optional
expansion boards will also activate the alarms related to communication with expansion boards and to probes connected
to expansion boards. For units with electronic expansion valve, all the drivers critical alarms will trip the compressors
6.4 Unit and compressors alarms and corresponding codes
In the following table the list of the managed alarms for both unit and compressors is shown.
Alarm code
Interface alarm label
Details
0
-
1
Phase Alarm
Phase alarm (Unit or Circuit)
2
Freeze Alarm
Freeze alarm
3
Freeze Alarm EV1
Freeze alarm on Evaporator 1
4
Freeze Alarm EV2
Freeze alarm on Evaporator 2
