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17.2 Forced and self-adjusting control
The condensing pressure control can be forced in cooling mode in two cases:
Case 1:
If HP > P54
– P195 – 0.5, the fans run at maximum speed for 30 minutes and the stages turn on at 1-second intervals. This 30-
minute runtime applies in case 2 as well.
- If intertwined coils are used, the first fan is turned on by the sensor that reads the highest value.
- If split coils are used, the function is managed by each circuit.
- If mixed coils are used, fans 1 and 2 are managed by each circuit. In the case of common fans 1 and 3, they are turned on by the sensor that
reads the highest value.
Case 2:
Management of control stage 1 (case of propeller fans with on/off control).
If fan stage 1 turns on more than 5 times in 10 minutes while the other stages are off, increase the stage differential by 4.5 b to shut off the
other stages. Normal control mode resumes (extra 4.5 b pressure eliminated and other stages allowed to turn on) if HP > P54 - P195 - P196 or
if HP > P181 + P183 for 10 minutes.
If the common fan 1 stage (common to both circuits) turns on more than 5 times in 10 minutes and the other higher stages on both circuits are
off, increase the stage differential by 4.5 b on both circuits.
The following message appears when P11 = split and mixed if stage 1 or 4 turns on more than 5 times in 10 minutes:
The following message appears when P11 = intertwined and mixed if stage 3 turns on more than 5 times in 10 minutes:
17.3 Fan speed control
The speed of the fans is controlled by the HP pressure sensor and the 0-10 V outputs on the motherboard and additional board 2. This control
functions in cooling mode only in order to reduce the sound level of the units. In heating mode, the fans run at maximum speed once a
compressor stage turns on.
If P21 = 2 or 3 (speed control with energy or acoustic optimisation) the speed of fan 1 on each circuit will be controlled; the other fans will be
adjusted to P180 by the on/off inputs.
The moment the fan starts in speed control mode and the moment the other stages are turned on must be separated by an interval of
3 seconds.
Variable speed drive (VSD):
In order for it to adjust the speed based on the 0-10 V signal, the variable speed drive selected must first be supplied electrically and informed
of the direction of rotation.
VSD power supply:
Power will be supplied, via the power contactors, by the control for fan 1 on circuit 1 (terminal 5 on terminal block J3), the control for fan 1 on
circuit 2 (terminal 6 on terminal block J3 on additional card 2) and the control for fan 1 common to both circuits (terminal 5 on terminal block J3
on additional board 2).
In both
heating
and
cooling
mode, these three outputs must be powered as soon as the unit is turned on by pressing the
On
/Off button on
the console or by turning off the Automatic Operation control. They will shut off after the Automatic Operation control is turned on or if the
On/
Off
button on the console is pressed.
Authorisation of VSD operation:
External VSDs (ALTIVAR) will not be controlled by the software. Instead, they will be controlled electromechanically via two auxiliary relays on
the KGs of the compressors (as soon as a compressor turns on, the associated relay sends the information to the VSD). As a result, running
the VSDs without the compressors will not be possible.
In the case of electronically commutated fans (built-in variable speed drive), authorisation for the VSDs to turn on is given by the board when
the fan contactor outputs are in the On position (no relay needed).
17.3.1 Fan speed control with split coils (P11 = split):
This configuration requires a variable speed drive for each circuit.
- 0-10 V output, stage 1, circuit 1, terminals 1-2 on motherboard terminal block J2
- 0-10 V output, stage 1, circuit 2, terminals 2-1 on terminal block J6 of additional board 2
Speed control mode is turned on as soon as the circuit is on.
a) P21 = 2 with acoustic optimisation
1 condenser fan module per circuit
= 1 stage (1 fan) with speed control
+ 1 single-speed stage (same as
standard)
2 condenser fan modules per
circuit = 1 stage (2 fans) with
speed control + 2 single-speed
stages (same as standard)
1er: stage 1, 2ème: stage 2
3ème: stage 3,
DEE = Interstage differential
H P x P R E S S U R E C O N T R O L
S T A G E 1 O N L Y
H P P R E S S U R E C O N T R O L
S T A G E 1 O N L Y
Summary of Contents for Magister 2 Series
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