mycom UD Series - Chapter 6 Troubleshooting; Compressor Start-up and Operation Issues

Chapter 6 Troubleshooting
UD-series Screw Compressors
6-1
Chapter 6 Troubleshooting
Table 6-1 Troubleshooting
Trouble Direct causes Factors Actions
01
Compressor
does not
start up
Power source is off.
Power source not
turned on after
inspection.
Prevent oversight by checking a
check sheet after inspection.
Main motor
malfunction
Most cases are due
to overload
protection circuit.
Refer to the motor instruction
manual as well for other causes and
actions.
Capacity control of
0% undetected by
unloader indicator
Malfunction of
micro-switch
Replace micro-switch.
Capacity control
hydraulic circuit
defect
Maladjustment of oil
flow control valve
(decreased too
much)
Readjust.
Leak or clogging in
pipes and solenoid
valves
Remove factors. Check oil
contamination level and replace oil
if necessary.
Unconfirmed
hydraulic pressure
Malfunction in hy-
draulic pressure
protection device,
pressure sensor,
relays, etc.
Identify malfunctioning devices,
examine their causes, and take
measures.
Then, replace malfunctioning
devices.
Clogging in
connecting pipes
Remove clogging. Check oil
contamination level and replace oil
if necessary.
Unconfirmed
cooling water
circulation
Malfunction in
devices such as
cooling water
pumps and related
circuits
Identify malfunctioning devices,
examine their causes, and take
measures.
Then, replace malfunctioning
devices.
Clogging in circula-
tion routes
Remove clogging.
Malfunction in mag-
nets, relays, etc., in
compressor start
circuit
Aging degradation
Replace with new devices.
Bad installation
environment
Replace ventilation fans, etc, if
malfunctioning.
Improve temperature, humidity, and
ventilation for installation site.
02
Compressor
stops imme-
diately after
startup.
Low pressure
protection circuit
(switch) activated
Insufficient refriger-
ant circulation
volume
 Insufficient refrig-
erant amount
 Insufficient refrig-
erant supply
 Heat exchange
failure at heat
exchanger
For insufficient refrigerant amount,
check the system and stop leak,
and then recharge refrigerant.
* Be cautious about moisture
contamination in the system.
For insufficient supply, inspect
expansion valves and liquid supply
strainers, and then take necessary
measures.
Also, inspect devices and
parameters (setting values) for
expansion value aperture (opening)
adjustment device, and then take
necessary measures..