EVCO c-pro nano CHIL - Manual (Page 123)

C-PRO NANO CHIL AND C-PRO MICRO CHIL – APPLICATION MANUAL
Pag. 123
6.16 Pressure Alarm Control
6.16.1 Management of high-pressure pressure-switch alarm
Via a digital input connected to an external pressure switch, it is possible to monitor an excess of
maximum condensing pressure. The high-pressure alarm AL11 (and AL12 for Circuit # 2) causes
the immediate stopping of the refrigerating circuit, also shutting down any compressors which may
be ON, and inhibiting the start-up of others.
This alarm is only detected when the machine is switched ON.
This is a manual-reset alarm.
6.16.2 Management of high-pressure transducer alarm
If condensing pressure exceeds a given threshold, a high-pressure alarm AL31 (and AL32 for
Circuit # 2) is generated. The alarm causes the immediate stopping of the refrigerating circuit, also
shutting down any compressors which may be ON, and inhibiting the start-up of others.
This alarm is only detected when the machine is switched ON.
This is a manual-reset alarm and it can be reset if in the meantime pressure has fallen below the
maximum threshold of a given differential value.
- PA21 = High-pressure alarm set point
- PA22 = High-pressure alarm differential
6.16.3 Management of low-pressure pressure-switch alarm (chiller mode)
Via a digital input connected to an external pressure switch, it is possible to monitor the presence of
a minimum intake pressure in the refrigerating circuit. The low-pressure alarm AL41 (and AL42 for
Circuit # 2) causes the immediate stopping of the refrigerating circuit, also shutting down any
compressors which may be ON, and inhibiting the start-up of others.
At start-up of the first compressor, the alarm is delayed for a given interval, to enable the
compressors to take the refrigerating circuit to full pressure.
The alarm is initially auto-resetting, unless it exceeds a given number of events within one hour
(PA14), in which case it becomes a manual-reset alarm.
- PA13 = Low-pressure alarm by-pass time
- PA14 = Maximum number of auto-reset low-pressure alarms
If, with the machine switched ON and in the presence of a request for chill from the
thermoregulator, low pressure is detected, compressor start-up is inhibited and a Start-up low-
pressure alarm AL21 (and AL22 for Circuit # 2) is displayed. The purpose of this condition is to
inhibit compressor start-up in the absence of Freon® gas in the circuit (there could be a refrigerant
leak from the piping system).
6.16.4 Management of low-pressure transducer alarm (heat pump mode)
If intake pressure falls below a given threshold, a low-pressure alarm AL41 (and AL42 for Circuit #
2) is generated. The alarm causes the immediate stopping of the refrigerating circuit, also shutting
down any compressors which may be ON, and inhibiting the start-up of others.
At start-up of the first compressor, the alarm is delayed for a given interval, to enable the
compressors to take the refrigerating circuit to full pressure.