Carel pCO1 series Application Program

Standard air-conditioning units
Carel Cod. +030221421 – Rel. 1.2 – April, 11, 2003
32
13.0 CONDENSER FANS
Condensing pressure control is available on ED type units, in which fans are managed based on condensing coil pressure and compressors state.
Fans are enabled by 0-10V modulating or digital outputs (on medium boards). Control is based on the condensation set point and differential, as
shown in the following diagram:
The following diagram shows fans operation with modulating outputs:
The maximum and minimum speeds of 0-10V outputs can be set; in case the set minimum speed is higher than 0V, the fan is operated at
minimum speed 1.0 bar below the condensation set point before switching off, as indicated in the diagram above.
13.1 SINGLE OR SEPARATE COILS
In case of single coil, only one output (on-off or modulating) is enabled. In case of units with at least one condensing probe and enabled on-off
outputs (medium boards), two on-off outputs may be enabled in sequence, dividing the differential by two.
In case of separated coils, two different outputs (on-off or modulating) are enabled, one per circuit.
13.2 NUMBER OF PROBES
Foreword: besides the values read by the probes, fans enabling always considers the compressors state.
In case of single probe and separated coils, fans enabling is based on the probe value for both circuits.
In case of two probes and single coil, fans enabling is based on the highest probes value.
In case of two probes and separated coils, fans enabling is based on the probe value of the relevant circuit.
In case no probe is present, fans are enabled simultaneously with the compressors; in case of single coil, fans are enabled when at least one
compressor is on; in case of separated coils, each compressor controls the fans of its own circuit.
13.3 PREVENT FUNCTION
High pressure alarm prevention with compressors stopped. Normally, the condensing fans turn on only if compressors are enabled, but in this
case they are forced so as to decrease pressure and try to prevent the high pressure alarm, which would cause unit shutdown. Pressure increase
with compressors stopped may be due to radiance on the coil. In case of 0-10V modulating fans, modulation is by-passed.
13.4 SPEED-UP FUNCTION
To overcome inertia at high-power modulating fans peak, they may be started at maximum speed for some seconds, then speed decreases to the
required value and modulation starts.
13.5 PRESSURE – TEMPERATURE CONVERSION
Both pressure and temperature probes can be selected. In case of pressure probes, branch I/O screens display the temperature value
corresponding to the pressure of each probe, based on the coolant type (to be selected in the Manufacturer branch).
Opening start point (100%)
Opening end point
(0%)
Compressor
state
Condensation
p
ressure
(
bar
)
CONDENSATION HP PREVENT HP
Condensation differential Prevent differential HP differential
Condensation set
14.0 16.0 18.0 20.0 23.5 24.5
2.0 bar 2.0 bar 1.0 bar
ON
OFF
Condensing fans
state
ON
OFF
Condensation
p
ressure
(
bar
)
Condensation differential
13.0 0% 14.0 16.0
2.0 bar
100%

Carel pCO1 series Specifications

General

Brand	Carel
Model	pCO1 series
Category	Controller
Language	English