EVCO c-pro nano CHIL - Manual (Page 124)

C-PRO NANO CHIL AND C-PRO MICRO CHIL – APPLICATION MANUAL
Pag. 124
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, which can be reset if in the meantime
pressure has risen above the minimum threshold by a certain differential value.
- PA11 = Low-pressure alarm set point
- PA12 = Low-pressure alarm differential
- PA13 = Low-pressure alarm by-pass time
- PA14 = Maximum number of auto-reset low-pressure alarms
In the presence of low temperatures of external air, intake pressure could fall below the minimum-
pressure threshold, thus inhibiting compressor start-up. In such a situation, it is possible to activate
a control, which shifts the alarm-control threshold to a higher value for a given interval from start-
up of the first compressor, leaving nevertheless in place all protection devices and pre-start checks.
- PA16 = Low-pressure control enable at low external temperature
- PA17 = Low-pressure alarm set point at low external temperature
- PA18 = Low-pressure alarm differential at low external temperature
- PA19 = Low-pressure alarm control duration at low external temperature
This control can only be enabled in heat-pump operating mode.
6.16.5 Low start-up pressure alarm
In a low-pressure condition (pressure switch or transducer-induced) and in the impossibility to
activate any of the compressors at the request of the same, there is a Low-pressure start-up alarm
AL51 (and AL52 for Circuit # 2). This is an auto-reset alarm, and thus should disappear, unless
there is a leak of Freon® gas from the circuit.
At compressor shutdown following a low-pressure alarm, this alarm is delayed by a given interval
PA20, to give the refrigerating circuit the chance to enable compressor start-up.