Capacity Regulation Of Compressor; Regulation; External Displacement Of Reference - Danfoss AKC 25H1 Description

Capacity regulation of
compressor
AKC 25H1
The step regulator in the controller can control up to nine capacity steps that can be
distributed on one, two or more compressors. (The controller has a total of nine relay outputs
that have to be distributed between compressor steps and condenser steps).

Regulation

The cut in compressor capacity is controlled by the actual value of the suction pressure and
whether the pressure is rising or falling.
- In the neutral zone there is no cut in/cut out of capacity steps.
- In the "+zone" and "-zone" bands cut in/cut out will depend on whether the pressure is rising
or falling. Cut in/cut out takes place with the selected time delays.
- In the "++zone" and "--zone" bands cut in/cut out takes place with the selected time delays.
- Refrigeration is stopped at pressures that are lower than the set "limit" value. (Cf. section on
"monitoring").
Control reference
The regulation is based on the set value and the pressure measured by pressure transmitter
PO.
Compressor Capacity Ctrl.

External displacement of reference

The reference for the regulation can be displaced by means of two functions:
1. An external voltage signal transmitted to the "EXT.REF" terminal. The voltage must be 0-10 V.
With this signal the reference can be displaced by up to 50 K in positive or negative
direction. 10 V gives max. displacement.
The reference change is damped with a time constant of approx. 300 seconds.
Compressor Capacity Ctrl. Settings Compressor Ctrl.
New reference = set reference + voltage signal x "K1 Gain K"/10
2. A night setback signal connected to terminal "S6". The signal must short circuit the input.
With this signal the reference can be displaced by up to 25 K in positive or negative
direction. (Cf. also later section "Temperature sensor").
The reference change is damped with a time constant of approx. 300 seconds.
Compressor Capacity Ctrl. Settings Compressor Ctrl.
The "Forced Nght" signal can also be generated via a setting in the controller.
Compressor Capacity Ctrl.
(This setting can also be made from a mastergateway's override function).
New reference = set reference + voltage signal x "K1 Gain K"/10 + "Night Ref.K".
Function description RC.1J.Z4.02 © Danfoss 09/1999
Settings Compressor Ctrl.
Settings Compressor Ctrl.
P0 SP ° C
___
K1 Gain K ___
Night Ref. K ___
Forced Nght OFF/ON ___
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