ECKELMANN VS 300, Operating Instructions Manual

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Function of VS 300
37 Doku-Version 2.05 - Firmware 2.10 - 15. September 2017
4.3.14 Demand-dependent calculation of setpoint
This function is only available in conjunction with case/coldroom controllers that deliver load-level
data (valve opening), e.g. UA 300 E.
In order to ensure optimum operation of a compressor pack and associate refrigeration points at minimum
operating cost it is appropriate for the low pressure controlled by the compressor pack to be set as a function of
refrigeration load at the refrigeration points.
The opening of the expansion valves at the refrigeration points lends itself as a reference input for this purpose.
With a load level equal to a definable maximum at a minimum of one refrigeration point served by the
compressor pack, it may be assumed that the temperature cannot be maintained reliably with the existing low
pressure at this/these refrigeration point/s. The limit of the load-level are programmable. In this instance low
pressure is decreased so as to be able t
0
supply sufficient refrigeration capacity.
Conversely, when the load level at all refrigeration points served by the compressor pack is less than a
definable minimum, it may be assumed that the refrigeration capacity supplied by the pack is more than
sufficient. In this instance the low pressure is increased in the interests of energy-efficient operation of the plant.
The t
0
setpoint should not be shifted up when superheat control is active on a transmitting case/coldroom
controller. In this instance the defined t
0
setpoint is retained or shifted down by increasing the valve opening.
4.3.15 Processing load-level information
Each case/coldroom controller on which load-level transmission is activated transmits up to four load levels to
the respectively assigned pack controller at intervals.
Decrease of low-pressure setpoint takes place on the pack controller when a single load level exceeds the
definable maximum load level. Increase of low-pressure setpoint takes place on the pack controller when the
load level of all case/coldroom controllers falls below the definable minimum load level.
When neither of the above conditions applies, the t
0
setpoint remains at the given value. No suction pressure
increase takes place as long as superheat control is active on at least one refrigeration point.
Only when superheat control is not active on any of the associated refrigeration points can low pressure be
increased according to the above rules. The reason for this is that, during superheat control, the valve opening
at the refrigeration point is normally small while refrigeration load continues high. In other words, this is a
precaution against erroneously increasing low pressure.
Change of low-pressure setpoint takes place within definable limits at definable increments and a definable
updating interval.