ECKELMANN VS 300 - Disabling Refrigeration Points

Function of VS 300
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Doku-Version 2.05 - Firmware 2.10 - 15. September 2017
With compressor control by refrigeration point, request for compressor actuation is coupled to the refrigeration
point solenoid valve. To ensure that cooling continues in the event of a CAN bus malfunction, the pack controller
switches automatically to the suction pressure controller in occurrence of a fault condition.
The compressor is shut down on failure of the case or coldroom controller. During direct coupling, no setpoints
are shown in the actual value screens.
Compressor control by refrigeration point is only available with UA 300 universal controllers for con
trol of solenoid valve.
Compressor control by speed controller:
With speed control, suction pressure is controlled by t
0
shift through the refrigeration demand of the display
case. For this purpose the UA 300 case controller supplies the control error to the VS 300 (deviation between
measured case temperature and temperature setpoint). The UA 300 can control two temperature zones. With a
two-zone controller the VS 300 forms the mean of the separate control errors. With a single-zone controller the
control error of the first zone is taken. Depending on the control error, a new to setpoint is calculated by the for
mula:
t
0
new
 t
0
alt
 Dt
M
*0.1
t
0
new
: New t
0
setpoint
t
0
old
: Previous t
0
setpoint
Dt
M
: Case control error
Cycle time is one minute, meaning that a new setpoint is calculated every minute. Shift of t
0
can only be made
within defined limits. The upper limit is defined by parameter S100/110 and the lower limit by parameter
S101/111. The VS 300 contains limits for day and night operation. If the t
0
value calculated during the daytime
lies beyond the defined limits in nighttime operation, the t
0
setpoint is reset to the upper or lower limit. In the
event of a bus fault or power failure, the lower t
0
setpoint (S101/111) is used for control. Following external fast
unload or restart, the VS 300 starts with the t
0
setpoint (S101/111) defined under t
0
-Min.
Minimum standstill time is 1 minute when compressor shutdown takes place during control with variable-speed
controllers.
If case temperature is too low by 2 K or more, the pack performs fast unload. The pack is re-enabled when the
case temperature is too high by 1 K or more after the minimum standstill time of 1 minute. The VS 300 then
starts with a t
0
setpoint 1 K higher than that prior to shutdown.
Following externa fast unload, the VS 300 starts with the t
0
setpoint (S101/111) defined under t
0
-Min. No t
0
shift
takes place during forced shutdown of the VS 300 (oil equalization), meaning that the t
0
setpoint remains un
changed for such time.
4.3.19 Disabling refrigeration points
In the occurrence of a fault on the compressor pack, the pack controller can transmit a refrigeration point disable
signal to all associate refrigeration points. The associate refrigeration points are case/coldroom controllers on
which the node address of the pack controller has been programmed in the controller configuration.
The refrigeration point disable signal is sent to all associate refrigeration points when no compressor or refrige
ration capacity is available. Possible causes of disabling of refrigeration points are:
S Auslösen des digitalen Eingangs der Sicherheitskette
S Betätigung des digitalen Eingangs für den Schnellrücklauf
S Vorübergehend über die Funktion Zwangsabschaltung Verdichter (Ölausgleich)
Refrigeration points are not disabled in the event of a low-pressure fault due to low suction pressure.