EN - 48
HP bar
Temperature
variation
18.7 Automated self-regulating control
This type of control adjusts the operation of the unit at the head end of the system.
If the compressor stops after running
for less than
5 minutes, the compressor stage cut-in value is changed but the cut-out points remain
unchanged.
The following message appears in the unit status table:
This message is saved in the fault memory:
Only one message is saved at a time, i.e. each control fault must be separated by another type of fault.
However, if the compressor runtime is
>
7 minutes, the initial state resumes.
Note:
This control mode is turned off if the system is switched to test mode or turned off via the On/Off button, or if the automatic machine
control or automatic pump control output opens.
18.8 Compensation
Enabled if P150
≠
1.
►
Purpose:
Allow the control system to anticipate changes in load on the loop by monitoring for variations in the return temperature.
►
Action:
It adjusts the controller time delay.
►
Principle:
The water return temperature is measured:
θ
t0 ; evaporator in cooling mode, condenser in heating mode at time t0 then t0 + P151.
The calculated temperature variation |
θ
t1-
θ
t0| is used to define the compensator coefficient.
The PID control polling time then becomes: remaining time × compensator coefficient.
Configuring the compensator coefficient:
The compensator coefficient can be set to between 0.1 and 1 (parameter P150).
If the compensator coefficient = 1, the function is disabled.
If the water return temperature variation < 0.5°C, there is no compensation.
The compensator coefficient is maximum when the temperature variation = 10°C between each time.
.
Compensator coefficient diagram:
19. CONDENSING PRESSURE CONTROL
19.1 Staged control for a machine with an air-cooled condenser
This type of control, known as CASCADE control, is used to control the air-cooled condenser fans.
The condensing pressure is adjusted in relation to the operation of the associated compressor. The fans are shut off by the On/Off button, the
automatic operation control or the emergency stop fault.
For each circuit, the number of condenser modules can vary and the number of HP control stages varies.
The first stage is turned on by a set setpoint value (P181
+
stage differential). Each additional stage is turned on by a set interstage differential.
Each circuit has its own stage differential and interstage differential.
- If the condenser air inlet temperature is
>
P182, all the fans are forced on while the compressors are on. Control resumes at P182
–
2°C.
- If the condenser air inlet temperature is
<
P182, the control is as follows:
Description of condensing pressure control possible per circuit:
LX 1800 to 2500:
2 V-frame condenser fan modules per circuit = 3 single-speed stages
A D A P T I V E S Y S T E M
C O N T R O L M O D E
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