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Chiller Water-cooled Screw
Power Panel
On the right side of the power panel, the terminal block for the main power connection is installed. This part
is connected to the Rated electrical input main power cable for control power and to neutral line to the ter-
minal block.
There is the OCR (Over-Current Relay) for 3 magnetic contactors and compressors to start the Wye-delta
of the compressor. 3 magnet contactors are installed to start Wye-delta within the power panel.
The starting inflow of current by Wye-delta start up is reduced by 1/3 by the direct start method. All wire
voltages (VL) of Wye and Delta coil configuration are Rated electrical input, but the phase voltage (VP) of
the Wye coil configuration is reduced by 1/3 of the Delta coil configuration. Also the line current (IL) is
reduced by 1/3 of the Delta coil. By using this principle, the compressor is equipped with the Wye coil con-
figuration. Coil configuration changes to Delta configuration after a few seconds for normal operation of the
compressor.
Fig. 33
Fig. 32
Compressor
OCR
Compressor
Wye-delta
Contactor
Main power
L1
L3
L2
1M
2M
1
4
5
2
3
6
1M
1M
2M
S
S
S
3
L
P
V
V
=
P
L
I
I
=
Wye Starting
Delta Running
L1
L3
L2
1M
2M
1M
1M 2M
2M
S
S
S
1
4
5
2
6
3
L
P
V
V
=
P
L
I
I
x
=
3
