ECKELMANN VS 3015 CT, Инструкция по эксплуатации, Страница: 28 / 219

Firmware V1.41 V1 08.11.2022 28/219
L.WorkFreq[Hz] = 35 Lower operating frequency: The minimum FC speed output by the pack controller is set
here. This must be selected to be greater than or equal to the minimum frequency to be output by the FC.
5.4.3.2 Loading / Unloading of Fixed-Speed Compressors During Operation with Capacity-
Controlled Compressors
Combined control operating mode with non capacity-controlled fixed-speed compressors (parameter
M.com.out.reg . = No)
With capacity-controlled compressors the additional capacity stage is only used for the speed controlled
compressor. The fixed-speed compressor is always operated at 100%. This means that the basic and capacity
stages of these compressors are always loaded and unloaded simultaneously.
The graph shows the controller profile of a compressor pack with 2 compressors with two-stage capacity
control.
The characteristic of the frequency converter must be configurable for this so that an output signal of 0 V at the
analogue output for compressor control corresponds to the minimum frequency and an output signal of 10 V
corresponds to the maximum frequency. The input signal of the frequency converter must be configured as 0 V
– 10 V interface.
Operating mode combined control with capacity-controlled fixed-speed compressors (parameter
M.com.out.reg
.
= Yes)
With compressor combined control of capacity-controlled fixed-speed compressors, a single-stage speed
controlled compressor is combined with one or more capacity-controlled fixed-speed compressors.
Using an adjustment of the compressor speed and the loading and unloading of the fixed-speed compressors,
this operating mode is designed to provide every operating point with the appropriate, continuously provided
refrigeration capacity.
The objective of this operating mode is to be able to provide the appropriate pack capacity for every load case:
if the pack exclusively uses single-stage compressors with the same or comparable capacity, load points
normally exist that cannot be represented by this pack. In such systems this results in the clocking or switching
on and off of mains compressors which reduces or eliminates the advantages of continuous control (low control
error and reduction in the switching frequency).
The advantage of the combination of a single-stage speed controlled compressor with capacity-controlled, i.e.
multi-stage fixed-speed compressors is that the sudden power variation when switching on or off the output
stage of a fixed-speed compressor is lower than when a complete compressor would be switched on or off.
Using the simultaneous change in speed of the speed controlled compressor, this small output variation can be
compensated for in all cases.
The simplified diagram below shows an example of the connection of a system with one single-stage FC
compressor in combination with three two-stage fixed-speed compressors: