32
Capacity
controller RS8HE202 © Danfoss 2017-07
AK-PC 781A
Design of a compressor and condenser control
Procedure:
1. Make a sketch of the system in question
2. Check that the controller’s functions cover the required
application
3. Consider the connections to be made
4. Use the planning table. / Note down the number of connections
./ add up
5. Are there enough connections on the controller module? – If
not, can they be obtained by changing an ON/OFF input signal
from voltage signal to contact signal, or will an extension
module be required?
6. Decide which extension modules are to be used
7. Check that the limitations are observed
8. Calculate the total length of modules
9. The modules are linked together
10. The connection sites are established
11. Draw a connection diagram or a key diagram
12. Size of supply voltage/transformer
1
Sketch
2
Compressor and condenser functions
AK-PC 781A
Application
Regulation of a compressor group
x
Regulation of a condenser group
x
Both compressor group and condenser group
x
Regulation of compressor capacity
Regulation sensor. Either P0, S4 or Pctrl
x
PI-regulation
x
Max. number of compressor steps
10
Max. number of unloaders each compressor
3
Identical compressor capacities
x
Different compressor capacities
x
Speed regulation of 1 or 2 compressors
x
Run time equalisation
x
Min. restart time
x
Min. On-time
x
Liquid injection in suction line
x
Liquid injection in cascade heat exchanger
x
External start/stop of compressors
x
Oil management
Oil injection in compressor. Shared or individual
x
Make a sketch of the system in question.
Follow these 12
steps
Receiver pressure control
x
Monitoring of oil level in receiver
x
Management of oil level in oil separator
x
Reset of oil management
x
Cutout of compressors at oil failure
x
Safety relays during forced compressor control
x
Suction pressure reference
Override via P0 optimization
x
Override via “night setback”
x
Override via "0 -10 V signal"
x
Regulation of condenser capacity
Regulation sensor. Either: Pc, Sgc or S7
x
Step regulation
x
Max. number of steps
8
Speed regulation
x
Step and speed regulation
x
Speed regulation first step
x
Limitation of speed during night operation
x
Heat recovery function for tap water control
x
Heat recovery function for heating
x
Controlling the gas cooler (high pressure valve). parallel valve, if
applicable
x
Summary of Contents for AK-PC 781A
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