23
11.5. Alternator Insulation Test
Before starting the generating set after installation, test
the insulation resistance of the windings. The Automat
-
ic Voltage Regulator (AVR) should be disconnected
and the rotating diodes either shorted out with tem
-
porary links or disconnected. Any control wiring must
also be disconnected.
A 500 V Megger or similar instrument should be used.
Disconnect any earthing conductor connected be
-
tween neutral and earth and megger an output termi-
nal to earth. The insulation resistance should be in ex-
cess of 1 MΩ to earth. Should the insulation resistance
be less than 1 MΩ the winding must be dried out.
11.6. Meccalte Alternator Troubleshooting
12. STORAGE
In case of the engine is not used for long time, preserve
the engine from corrosion, faulty matters in order to
run the engine operation easily and keep it long main
-
tenance.
12.1. Engine preservation
Notes:
• There are three grades of preservation listed below,
(together with their applications) for complete engines
and associated equipment, such as radiators, silencers,
spares etc.
• For all recommended preservatives contact the Ap
-
Alternator does not excite
High voltage at no load
Blown fuse
Insufficient residual voltage
No residual voltage
Replace fuse
Increase speed by 15 %.
For an instant apply on the (+) and
(-) terminals of the electronic
regulator a 12V battery with 30Ω
resistor in series respecting
the polarities.
Check connection cables as per
attached drawings.
Reset voltage
Check engine speed
Check windings
Reset voltage potentiometer
Substitute regulator
Reset voltage potentiometer
Current to high, power factor lower
than 0,8; speed lower than 4% of
rated speed
Substitute regulator
Check diodes, disconnect cables.
Reset voltage potentiometer
Substitute regulator
Reset voltage potentiometer
Substitute regulator
Connections are interruptedAfter being excited alternator
does no excite
Voltage potentiometer out of
setting
Invention of protection.
Winding failure
Low voltage at no load
Voltage potentiometer out of
setting
Failed regulator
Voltage potentiometer out of
setting
Intervention by protection
Failed regulator
Rotating bridge failure
Lower than rated voltage
at load
Higher than rated voltage
at load
Unstable voltage
Voltage potentiometer out of
setting
Failed regulator
Speed variation in engine
Regulator out of setting
To Next Page
