Compressor Control; Starting Control; Rotation Control - Hitachi RCUE40AG2 Service Manual

Control system

4.3. Compressor control



Compressor control

pag. 53
SMGB0003 rev.0-01/2007
Compressor Control:

1. Starting control

2. Time Guard
3. Sequential starting control

4. Rotation control

4.3.1. Starting control
Starting control, Time Guard and Sequential starting control.
These three controls are performed in the control circuit on PCB.
∆ starting control of screw compressor (
−
at minimum load. (for 30 seconds)
Time guard function which limits the frequency of Run/Stop when cooling/
−
heating load is small (at minimum 3 minutes of stop time to avoid more than
6 ON/OFF in one hour)
Sequential starting control which reduces the starting current of the unit.
−
(Cycles start sequentially with a 1 minute delay between each one. Finally all
work together for 30 seconds before capacity control starts.).
4.3.2. Rotation control
Run/Stop order of compressor is modifi ed in each Run/Stop in order to balance
the compressors operation time and unit life is prolonged.
ON
No. 1
Compressor
OFF
ON
No. 2
Compressor
OFF
operation lasts 5 seconds),
Stop the
compressor
whose operation
time is longest
Operate the
Stop the
compressor
compressor
whose
Operate fi rst
operation
time is
longest
4 4