Technical information

TROUBLE SHOOTING
26 May 2010 / M-SC3.5 / EN
5.1.3 Other electrical problems
PROBLEM POSSIBLE CAUSE WHAT TO DO?
No output (Voltage) at all. • Circuit breaker "off" or faulty fuse. Check switches and fuses and measure
directly on the alternator to exclude external
causes.
• Low engine RPM. Check the engine RPM and adjust (refer to
special procedures).
• Loss of residual magnetism. Check the residual magnetism and flash the
alternator (refer to special procedures).
• Capacitor loose or broken. Check by independent excitation if the problem
is in the capacitor or in the windings.
• Rotor diodes broken. Check the diodes in the rotor (refer to special
procedures) The M-SC3.5 has two diodes in
the rotor. It happens very rarely that both are
broken. When only one diode is broken the
voltage will be low but will not varnish
completely.
Generator output voltage too
low when no load is on it (less
than 210V).
• No load at all or very low load. Switch on a load and check voltage.
• Engine is not reaching the rated RPM. Refer to special procedures to readjust RPM.
• Defective capacitor. Check capacitor and replace if necessary
(refer to special procedures).
• Defective diode (one of the two) Check the diodes in the rotor and replace
(refer to special procedures).
Generator output voltage too
low when no load is on it (less
than 210V).
• No load at all or very low load. Switch on a load and check voltage.
• Engine is not reaching the rated RPM. Refer to special procedures to readjust RPM.
• Defective capacitor. Check capacitor and replace if necessary
(refer to special procedures).
• Defective diode (one of the two) Check the diodes in the rotor and replace
(refer to special procedures).
Generator output voltage too
low under load (less than 210V).
In no load condition it is ok.
• Generator is overloaded. Switch off a load; (part off) consumers.
• Engine is not reaching the rated RPM. Refer to engine RPM problems.
• Defective capacitor Check capacitor and replace if necessary
(refer to special procedures).
Generator voltage too high,
(more than 245V)
• Engine is running too fast (RPM too
high).
Check engine speed and adjust (refer to
special
(more than 245V).procedures).
• Over-energising due to defective
capacitors
Check capacitor specification and replace
capacitors if necessary.
• Presence of a strong capacitive load
(leading power factor)
Compensate for this capacity and seek for
experts advice.
Generator voltage fluctuates. • Disturbances on the electrical system/
user side.
Check if electrical load is fluctuating
• Engine runs irregularly. When engine runs irregularly refer to section:
"Engine runs irregularly".