Warnings; Service Address; Special Procedures Alternator; Residual Voltage Check / Excitation Procedure - Whisper Power W-SC3 User Manual

5.2.3

Warnings

Generator must be shut off immediately if:
• Motor RPM suddenly rises or drops.
• Unusual noise comes from generating set.
• Exhaust gases suddenly colour dark.
• Engine failure warning light is on
5.2.4

Service address

If you cannot correct a problem with the aid of the mal-
function table, contact your Whisper Power Service Centre
or Whisper Power in the Netherlands for an extended
service list, tel: INT +31-20-3422100.
5.3

SPECIAL PROCEDURES ALTERNATOR

Figure 14
5.3.1 Residual voltage check / excitation
procedure
When residual magnetism disappears there is no residual
voltage. Residual magnetism can disappear after the
generating set being out of service for a long period or
suffered a short circuit. This can be solved by charging the
capacitor ("flashing") independently with a small 9 Volt
battery. This can be done while the engine is stationary
and the wiring is connected.
If the generating set battery is used for
flashing one must take care. A short circuit
can cause heavy sparking, fire and injuries
When flashing does not bring back voltage, the
capacitor(s) should be renewed. When this does not help,
the rotating rectifier diodes should be tested and a winding
resistant test should be executed.
5.3.2

Testing rotary rectifier diodes

The diodes in the rotor can be checked with a multimeter.
When both diodes are faulty the alternator will not
generate any voltage. When only one diode is faulty the
EN / W-SC3 Mobile / January 2011
1 Varistor (420V);
2 EMC capacitors (4,7nF - 630V);
3 Diodes (25A - 1200V).
alternator will generate about half the normal voltage. The
flexible lead connected
disconnected at the terminal end, and the forward and
reverse resistance checked. A healthy diode will indicate a
very high resistance (infinity) in the reverse direction, and
a low resistance in the forward direction. A faulty diode will
give a full deflection reading in both directions with the test
meter on the 10,000 ohms scale, or an infinity reading in
both directions. The problem can also be in a faulty surge
suppressor which is a metal-oxide varistor connected
across the diodes, or the ESD capacitor. Replace the
diodes, the suppressors and the capacitors.
5.3.3

Winding resistant values

If after establishing and correcting any fault on the
capacitor and diodes output is still low when separately
excited, then the main rotor, stator and exciter stator
winding resistance should be checked as the fault must be
in one of these windings. The respective leads must be
disconnected before taking the readings.
Resistance values should be within 10% of the values
given in the table below:
Resistance
• Resistance both main stator windings
in series
• Resistance both rotor windings
• Resistance battery charger winding
• Resistance exciter stator winding
TROUBLE SHOOTING
Fig15
to the diode should
50Hz
1.2 Ohm
2.1 Ohm
0.15 Ohm
2.4 Ohm
25
be