Carel pCO1 series Application Program

Standard air-conditioning units
Carel Cod. +030221421 – Rel. 1.2 – April, 11, 2003
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15.4 COMPRESSOR ALARMS
Compressors alarms are distributed in two digital inputs, with an exception for the two-compressor ED configuration on small boards, in which
the alarms are compacted in a single digital input.
In case two digital inputs are present, the alarms mean Thermal alarm / High and Low pressure alarm.
In case a single digital input is present, the alarm means General alarm.
If any alarm input shall not be used, the 24Vac supply needs to be energised.
As for electrical connections of alarm digital inputs, refer to the pCO1 – pCO2 boards technical manual.
15.4.1 HIGH PRESSURE – THERMAL ALARM
Immediate alarm originated by external pressure switch or compressor overload; the digital input switches from closed to open and compressor
is immediately stopped. To start the compressor again, the user has to rearm the alarm manually by pushing the terminal Alarm button, provided
that the pressure switch or compressor overload have rearmed energising the digital input. After the compressor has turned off, timing is
enabled; for this reason, after alarm rearming, the compressor could not immediately turn on again.
15.4.2 LOW PRESSURE ALARM
Delayed alarm originated by an external pressure switch. When opening, the digital input enables two timers; if, when the timers delay time
(programmable by screen) elapses, the contact is open, the compressor turns off and the alarm goes off. On the contrary, if the contact closes
before delay time elapses, the alarm does not go off and timers reset. Timers are: running compressor delay time and compressor start delay
time. Running delay is always counted, whereas compressor start delay is counted only if the input opens immediately after compressor start
and allows for fluid stabilisation. The two timers are counted in sequence.
To start the compressor again, the user has to rearm the alarm manually by pushing the terminal Alarm button, provided that the pressure switch
has rearmed energising the digital input. After the compressor has turned off, timing is enabled; for this reason, after alarm rearming, the
compressor could not immediately turn on again.
15.4.3 GENERIC ALARM
Alarm including all compressor safety devices in a single digital input, used on two-compressor small boards. This alarm goes off immediately
when opening the digital input and locks the compressor. To start the compressor again, the user has to rearm the alarm manually by pushing the
terminal Alarm button, provided that the digital input has been energised. After the compressor has turned off, timing is enabled; for this reason,
after alarm rearming, the compressor could not immediately turn on again.
16.0 HEATERS
The heaters are managed as simple ON-OFF loads. Normally up to 2 heaters with the same power can be managed, connected to the 2 outputs.
“Binary management” allows the use of three heating steps with just two outputs. Consequently, there are two possible options:
management of 2 loads with different power values;
management of 3 loads. To use this system, a recognizer is required (NOT supplied), which, connected to the outputs, reads the logic and
activates the loads.
The outputs behave as follows:
CODE 2 DIFFERENT LOADS 3 LOADS
STEP 1 Relay 1=On Relay 2=Off 10 Heat.1=On / Heat.2=Off Heat.1=On / Heat.2=Off /
Heat.3=Off
STEP 2 Relay 1=Off Relay 2=On 01 Heat.1=Off / Heat.2=On Heat.1=On / Heat.2=On /
Heat.3=Off
STEP 3 Relay 1=On Relay 2=On 11 Heat.1=On / Heat.2=On Heat.1=On / Heat.2=On /
Heat.3=On
The outputs are activated with a slight delay from one to the other, to avoid simultaneous peaks.
16.1 HEATER ALARMS
Each heater is provided with a digital input to be connected with a compressor overload or differential for signalling any failure.
If any input shall not be used, the 24Vac supply needs to be energised.
Immediate alarm originated when the digital input switches from closed to open; the heater is immediately disabled. To enable the heaters again,
the user has to rearm the alarm manually by pushing the terminal Alarm button, provided that the compressor overload or the differential have
rearmed energising the digital input.

Carel pCO1 series Specifications

General

Brand	Carel
Model	pCO1 series
Category	Controller
Language	English