4 Troubleshooting
Pressure sensor characteristics
SMGB0120 rev.0 - 11/2017
128
4.11 Pressure sensor characteristics
4.11.1
High-pressure sensor
0
2.5
5.0
4.5
2.5
0.5
(V)
(Mpa)
4.11.2
Low-pressure sensor
0
1.0
2.0
4.5
2.5
(0.3)
(V)
(Mpa)
0.5
(-0.1)
4.12
Procedures for trouble
The following table shows efficient checking procedures for trouble.
Fault
Possible cause
Check/corrective action
Compressor does not
operate
Interlock circuit for chilled water pump is open
1. Check the pump contactor. Repair or replace, if
necessary.
2. Check for the faulty pump.
Electrical protective devices are tripped.
Remove the causes, and reset the “ON” button.
See the following causes.
Incorrect wiring connection for compressor power
source
Interchange two of three terminals R, S and T at the
main power source terminals.
Compressor stops on
high pressure switch
Excessively high discharge pressure
See
High discharge pressure
Malfunction of high pressure switch
Readjust the setting or replace, if defective.
Compressor stops on
overcurrent relay
Excessively high discharge pressure and suction
pressure
See
High discharge pressure
and
High suction
pressure
.
High or low voltage, single-phase or phase
imbalance
Check the power supply line and contactors.
Repair, if necessary.
Loose connection
Tighten the loose electrical connection or repair, if
necessary.
Faulty compressor motor
Check the compressor motor. Repair or replace, if
necessary.
Faulty overcurrent relay
Replace it, if necessary.
