KGL Operating Manual – VS 3010 BS
2018-07-02
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This threshold (t0 Comp. OFF Z2) can be configured in menu 3-4. The monitoring of the starts is not active for
compressor control via consumer. For compressor control via consumer, the compressor is always coupled
with the solenoid valve of the refrigeration point.
If any of the following operating statuses occurs, the compressor with the "disable refrigeration points" signal is
disabled:
If no compressor is available (due to Manual OFF, HP fault or motor protection)
If oil equalisation is performed by the controller
In the case of an error, the pack controller automatically changes over to the low-pressure controller so that
the cooling is also guaranteed in the event of a CAN bus fault. The compressor is switched off in the event of
failure of the case controller. The actual value screens do not show any setpoints for the direct coupling.
The consumer control operating mode is not intended for use together with the UA 300 E / UA 400 E.
If this operating mode is set in the pack controller, this can result in stock loss or damage to the
system.
4.4.7 Compressor packs with suction gas bypass (evaporation pressure regulator)
If the pack controller is used for compressor packs in which both temperature ranges regulate in the plus
range, suction gas bypass can be used. Using the suction gas bypass, both suction lines can be connected in
part-load operation (night operation). The required refrigeration capacity can then be provided with the usually
smaller Z2 compressor.
Mode of operation
The suction gas bypass opens if the pressure of the Z1 suction line exceeds the pressure set on the
evaporation pressure regulator. The setting value of the evaporation pressure regulator must be larger than t0-
Sollwert-Tag and similar to t0-Sollwert-Nacht of the Z1 compressors so that the evaporation pressure regulator
is only active during night operation.
The suction gas pressure of the Z2 compressor can increase during night operation due to the loading of a Z1
consumer or Z2 consumer. Z2 capacity stages are loaded if the pressure at the Z2 compressor is greater than
the specified setpoint. During night operation, the Z2 compressors can cover the refrigeration requirement of
the Z1 and the Z2 refrigeration points. If the refrigeration requirement of the Z1 refrigeration points increases,
the suction gas pressure of the Z1 compressors increases above the t0-Sollwert-Nacht that results in switching
on a Z1 compressor.
Example
Setpoint t0 Z1 daytime operation = -7 °C
Setpoint t0 Z1 night operation = -5 °C
Neutral zone Z1 night operation = 4 K
Setpoint t0 Z2 daytime operation = -11 °C
Setpoint t0 Z2 night operation = -9 °C
Evaporation pressure regulator setting value = -5 °C
The suction gas pressure of the Z2 compressors increases if a Z2 consumer has been loaded. Z2 capacity
stages are loaded if the suction gas superheat is greater than -9 °C plus half the Neutral Zone. The suction
gas pressure of the Z1 compressors increases if a Z1 refrigeration point has been loaded. If the suction gas
superheat is higher than -5 °C, the evaporation pressure regulator (suction gas bypass) opens and lets the
suction gas pressure of the Z2 compressors increase.
Due to this process, all available Z2 compressors are loaded first during night operation. Z1 compressors
