mycom UD Series User Manual

Chapter 6 Troubleshooting
UD-series Screw Compressors
6-5
Trouble Direct causes Factors Actions
06
Abnormally
high
discharge
temperature
High oil supply
temperature
Heat exchange
failure in oil cooler
For water-cooled oil cooling, refer to
“Heat exchange failure at
condenser (heat exchanger)” in
item 05.
For liquid-injection oil cooling,
inspect liquid supply expansion
valve, temperature sensor, related
relays, wiring, terminals, etc., and
take necessary measures.
Failure in oil
temperature
increase protection
feature
Inspect temperature protection
device (switch), temperature
sensor, related relays, wiring,
terminals, etc., and take measures.
Defect in discharge
temperature
detection and
protection devices
Malfunction in
temperature protec-
tion device,
temperature
sensor, relays, etc.
Identify malfunctioning devices,
examine their causes, and take
measures.
Then, replace malfunctioning
devices.
Insufficient supply
oil
Refer to item 04,
“Low hydraulic
pressure (low
oil-supply pres-
sure)”.
Same as on the left
07
Leak from
mechanical
seal
Initial leak after
replacement until
mating surface(seal
and shaft) fit each
other.
Initial wear stage of
mating surface.
For initial leak, amount of leak might
increase temporarily. However, it
will gradually decrease, so check
that the amount of leak does not
increase continuously.
Period of initial leak might differ
according to design and operating
conditions. 200 hours can be a
rough guide.
Damaged sliding
surfaces due to
excessive heat of
sliding surfaces
Most cases are due
to excessive
repetition of
compressor
start/stop.
*Under normal
operating
condition, more
than 4 times /h is
considered as
excessive.
If heat load is below the design
operating conditions, re-examine
the conditions and set the control
settings to fewer start/stop times.
For capacity control malfunctions,
see item 10, “Capacity control
malfunction”.
A lot of refrigerant
mixed into the
lubricant, resulting
in decreased
viscosity.
For liquid backflow operation,
remove the causes.
For malfunction of oil heater and
other devices on control circuit,
replace them.
Overheat operation
Refer to Factor “Insufficient
refrigerant circulation volume” in
item 02.
High supply oil
temperature
Refer to the Direct cause “High
supply oil temperature” in item 06.

mycom UD Series Specifications

General

Brand	mycom
Model	UD Series
Category	Air Compressor
Language	English