Testjng The Exciter Windings - Westerbeke 6.5 MCG Service Manual

BC GENERATORS TROUBLESHOOTING
TESTING
THE EXCITER
WINDINGS
AC voltage can be measured across the capacitor electrical
connections while the generator is operating. This voltage
may be as hlgh as 350 to 400 volts AC.
This AC voltage build-up is accomplished as the exciter
winding for each capacitor charges the capacitor and the
capacitor discharges back into the winding.
This
flow of
saturating AC in the exciter winding produces a phase-
imbalance type of filed that affects the auxiliary windings
of the
rotor:
The AC voltage reading is taken between the two electrical
conn~ctions
on each separate capacitor with the generator
operating at its correct no load speed.
EXCITER WINDING INTEGRITY (RESIDUAL AC VOLTAGE)
The condition of each exciter winding can
be
determined
by the residual AC voltage each exciter winding should be
producing with the generator running at proper no load speed.
To do thls: Unplug all connections from the capacitor. Locate
the electrical connection for each winding end. Place your
AC volt meter connects across these two connections. Start
the generator and observe the residual AC voltage produced
by the winding. Check the other exciter winding in the same
way. Residual AC voltage lower than listed below will.
indicate a faulty winding.
RESIDUAL VOLTAGE (EACH WINDING GROUP)
MEASURED BETWEEN #50 AND #9 OF EACH GROUP
7·9 VOLTS AC.
TESTING WINDING LEADS
FOR NO CONTINUITY
TO METAL CASE
THERE SHOULD BE NO
CONTINUIJY BETWEEN LEADS
50HZ AND 19 TO CASE
GROUNDS
#60hz
MEASURE THE RESISTANCE
VALUE OF THE EXCITER
WINDINGS BETWEEN THE
END LEADS OF EACH WINDING
73
MEASURING VOLTAGE
GENERATOR RUNNING
SET THE METER DIAL
ATAC VOLTS