Operating manual - SAB 120-151 A-frame (including ATEX)
008668 en 2019.08
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Troubleshooting
Compressor unit, general issues
Symptom
Probable cause Solution
Compressor cannot
start
Electrical supply.
Check main switch and fuses. Reset
emergency stop switch, etc.
Alarm in control system.
Register the alarm, correct if neces-
sary and reset (refer to the Control
manual).
Oil level too low.
Charge oil.
Compressor starts
but stops
immediately
Oil system failure (temperature,
pressure, level).
Check oil level.
Check valve positions.
Oil filter differential
pressure too high
Oil filter clogged. Replace oil filter.
Oil temperature too
high (and high dis-
charge
temperature)
Valves in oil system are not fully
open.
Check stop valves and opening posi-
tion of the oil regulation valve.
3-way oil temperature control valve.
(Water-cooled or refrigerant-cooled
(Thermosyphon)).
Check function, replace the sensor
element.
Insufficient oil cooling function
(water-cooled).
Check oil cooler, fouling, water inlet
temperature, (too high), water flow
(too low).
Insufficient oil cooling function (re-
frigerant-cooled).
Check/drain accumulated oil in the
oil cooler. Check that the gravity fed
refrigerant system is full flooded.
Insufficient oil cooling function
(liquid injection).
Check the settings in control system,
valves and strainer in liquid injection
line.
Compressor protection valve is open
or leaking.
Check the discharge pressure safety
cut-out settings. Check the pilot and
main protection valve.
Discharge tempera-
ture very low. Oil
temperature low and
oil may be foaming
in oil separator
Excessive liquid in suction line/liquid
slugging.
Check evaporator (and economiser
(optional)) and expansion valve
function. Decrease the rate of evap-
orator temperature “pull down”.
Liquid injection (optional)
overfeeding.
Check the settings in control system
(increase the set point). Check the
stability of the liquid injection.
Suction pressure
high and insufficient
refrigeration
capacity
Compressor protection valve is
opening or leaking.
Check the discharge pressure safety
cut-out settings. Check the pilot and
main protection valve.
Oil return valve fully open.
Adjust the regulating valve accord-
ing to manual.
Suction strainer clogged.
Clean strainer.
Table 9: Compressor unit, general issues
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