Meggering; Special Procedures Engine; Setting The Rpm - Whisper Power M-SQ27 User Manual

5.3.5

Meggering

One can try to measure resistance between the housing
and the windings with a multimeter which should read
infinity. When readings are infinity but a fault is suspected
one can do a high voltage resistance test (MEGGERING)
This procedure should be carried out by an expert. The AVR
should be disconnected during this test. A 500V 'Megger' or
similar instrument should be used. The insulation resistance
to earth of all windings should be in excess of 2 MOhm.
Should the insulation resistance be less than this value,
drying out the generator windings is essential. Drying out
can be carried out by direct warm air (60-80ºC) from a fan
heater or similar apparatus into the generator air inlets or
outlets.
5.4

Special procedures engine

5.4.1

Setting the RPM

RPM is set by the manufacturer and should not need
readjustment! However a very slight offset after running in
could occur. RPM can be measured by a frequency meter.
Before readjustment check any other explanation for the
wrong speed. Engine speed is set at the factory at nominal
1500 (50 Hz) RPM. A RPM drop of 5% at full load is
acceptable. Therefore a no load setting should be at ± 1575
RPM = 52.5 Hz. Under no circumstances should the RPM
be under full load below 1470 RPM = 49 Hz. When no cause
can be found for a wrong speed, the setting can be
adjusted:
EN / M-SQ 27 / August 2020
01 Engine speed adjusting screw
Fig. 27: Location engine speed adjustment screw
It is very important to identify the correct setting assembly
(see fig. 27). The screw is to be locked in position with the
lock-nut.
TROUBLESHOOTING
01
37