mycom i160S - Page 102

2203M4JE-MY-iS2-N_2017.04.
Chapter 6 Troubleshooting
Screw Compressor i-series
6-4
Symptom
Direct cause
Root cause
Action
05
Abnormally
high
pressure
(Abnormal
discharge
pressure)
Refrigerant is
excessive.
In some cases,
insufficient cooling
is judged as
caused by
insufficient
refrigerant and, as
a result, refrigerant
is charged
repeatedly.
Properly adjust the refrigerant
charge.
Capacity of heat
changer is
insufficient.
If the symptom is caused by
change in operating conditions,
re-examine the conditions for
improvement.
If improvement is difficult, add
heat exchangers or increase their
sizes.
Discharge oil
pressure detection
function is defective.
Failure of high
pressure protection
switch, pressure
sensor, relay, etc.
Identify defective device(s),
investigate causes of failure and
take necessary actions.
Then, replace failed device(s).
Clogging of
pressure pipe
Remove clogging, and check oil
for contamination/replace oil.
Outlet shut-off valve
of oil separator is
closed.
Operator forgot to
restore after shut
down operation.
Human error
Open the valve or perform
emergent stop.
Be sure to conduct tagout while
handling valves.
Be sure to check valves before
starting the compressor.
06
Discharge
temperature
is abnormally
high.
Overheated during
operation
Insufficient
refrigerant flow
See the causes listed in item 02
above.
Heat load on load
side is higher than
design value.
Inspect the conditions on load
side (warehousing volume,
opening/closing of doors, etc.),
and take necessary measures.
Failure of low
pressure protection
switch, pressure
sensor, relay, etc.
Identify defective device(s),
investigate causes of failure and
take necessary actions.
Then, replace failed device(s).
Non-condensable
gases mixed into
the system
Leak on low
pressure side
Perform a leak check, and take
necessary measures.
Air-purge the heat exchanger.
Oil supply
temperature is high.
Heat exchange
failure in oil cooler
For water-cooling system, see
"Heat exchange failure in heat
exchanger" in item 05 above.
For liquid cooling system, check
liquid supply expansion valve,
temperature sensor and related
relays/wiring/terminals, and take
necessary actions.
Oil temperature
rise protection
feature does not
function.
Check temperature protection
switch, temperature sensor and
related relays/wiring/terminals,
and take necessary actions.