Alternator Trouble Shooting; Engine Trouble Shooting - Atlas Copco QAS 14 Instruction Manual

6.4 Alternator trouble shooting

Symptom
Alternator does not excite
After being excited alternator
does not excite
Low voltage at no load
High voltage at no load
Lower than rated voltage at
load
Higher than rated voltage at
load
Unstable voltage

6.5 Engine trouble shooting

The table below gives an overview of the possible engine problems
and their possible causes.
6.5.1 The starter motor turns the engine too
slowly
– Battery capacity too low.
– Bad electrical connection.
– Fault in starter motor.
– Wrong grade of lubricating oil.
6.5.2 The engine does not start or is difficult
to start
– Starter motor turns engine too slowly.
– Fuel tank empty.
– Fault in fuel control solenoid.
– Restriction in a fuel pipe.
– Fault in fuel lift pump.
– Dirty fuel filter element.
– Air in fuel system.
– Fault in atomisers.
2954 2100 01
Possible cause
Blown fuse.
Insufficient residual voltage.
No residual voltage.
Connections are interrupted.
Voltage potentiometer out of setting.
Intervention of protection.
Winding failure.
Voltage potentiometer out of setting.
Failed regulator.
Voltage potentiometer out of setting.
Intervention by protection.
Failed regulator.
Rotating bridge failure.
Voltage potentiometer out of setting.
Failed regulator.
Speed variation in engine.
Regulator out of setting.
Corrective action
Replace fuse.
Increase the speed by 15 %.
For an instant apply on the + and – terminals of
the electronic regulator a 12 V battery voltage
with a 30 Ω resistor in series respecting the polar-
ities.
Check connection cables as per attached draw-
ings.
Reset voltage potentiometer.
Check rpm.
Check windings.
Reset voltage potentiometer.
Substitute regulator.
Reset voltage potentiometer.
Current too high, power factor lower than 0.8;
speed lower than 10% of rated speed.
Substitute regulator.
Check diodes, disconnect cables.
Reset voltage potentiometer.
Substitute regulator.
Check regularity of rotation.
Regulate stability of regulator by acting on
"STABILITY" potentiometer.
– Cold start system used incorrectly.
– Fault in cold start system.
– Restriction in fuel tank vent.
– Wrong type or grade of fuel used.
– Restriction in exhaust pipe.
6.5.3 Not enough power
– Restriction in a fuel pipe.
– Fault in fuel lift pump.
– Dirty fuel filter element.
– Restriction in air filter/cleaner or induction system.
– Air in fuel system.
– Fault in atomisers or atomisers of an incorrect type.
– Restriction in fuel tank vent.
– Wrong type or grade of fuel used.
– Restricted movement of engine speed control.
– Restriction in exhaust pipe.
– Engine temperature is too high.
– Engine temperature is too low.
Instruction manual
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