mycom SCV Series Instruction Manual page 125

Trouble
10 Capacity Capacity control
control hydraulic line defect
malfunction
Unloader piston
does not move.
(A defect of the
capacity control
hydraulic line is one
of the causes, but
described
separately.)
11 Abnormal Insufficient
vibration alignment between
and/or compressor shaft
noise of and motor shaft
compressor
Large axial runout
of Male rotor
SCV-series Screw Compressors
Direct causes
Maladjustment of oil
flow controller valve
Leak and clogging
in solenoid valve
gland and oil pipes
Damaged cap seal
for unloader piston
Pinched cap seal
Worn cap seal
Refrigerant gas
retention in
unloader cylinder
If vibration value is
higher in the axial
direction,
insufficient
alignment might be
the cause.
Uneven tightening
for thrust bearing
glands
Loose thrust
bearing
Imprecision in
dynamic balance of
rotors
Factors
Readjust it.
Remove factors. Check oil
contamination level and replace oil
as necessary.
Check oil contamination level and
replace oil as necessary.
Replace O-ring, cap seal, etc.
Replace O-ring, cap seal, etc.
Check oil contamination level and
replace oil as necessary.
Replace O-ring, cap seal, etc.
Stop compressor. Operate oil pump
and repeat loading and unloading to
purge refrigerant gas from cylinder.
For liquid flow-back operation,
remove the causes.
For malfunction of oil heater and
other devices on control circuit,
replace them.
Realign the shaft-center.
If abnormal vibration and noise fre-
quently occur in monocoque unit,
hot alignment is recommended.
(operate compressor at design
conditions once to increase shaft
temperature and realign before the
temperature decreases).
If loose locknuts exist and no other
fault is found in parts such as thrust
bearing, tighten locknuts evenly.
Forgetting to bend lock washer claw
or wear of thrust bearing rolling
element (ball) can be considered.
→Check for any defects in thrust
bearings. If there are any defects,
replace it. Then perform end
clearance adjustment as well as
axial runout check, and
reassemble it.
If no other causes for abnormal
vibration are found, and if on-site
overhaul has been repeatedly
performed, imprecision in rotor
dynamic balance might be the
cause of abnormal noise and
vibration. If this is the case,
overhaul and inspect compressor
where rotor dynamic balance
measurerment and adjustment is
feasible.
6-8
2205Q2JE-HO-S6-N_2020.01.
Chapter 6 Troubleshooting
Actions