Westerbeke 9.0 BCG Technical Manual page 211

Group # 1 - Measure resistance value between terminal with lead # 1, and terminal with lead # 3. (Check
that there is no continuity of Group # 1 windings to the case ground.)
Group #2 - Measure resistance value between terminal with lead # 4, and terminal with lead # 6. (Check
that there is no continuity of Group #2 windings to the case ground.)
Check for a possible short between the two groups of stator windings by placing one lead of the
ohmmeter on the terminal with stator lead 3 and the other ohmmeter lead on the terminal with stator
lead # 6. There should be no continuity between the two groups of stator windings.
c.
Exciter Windings
BCG 4.0KW: 1.9 Ohm
BCD 4.4KW: 1.9 Ohm
BCG 6.5KW: 2.2 Ohm
BCD 6.0KW: 2.2 Ohm
An AC voltage is induced in these windings by the
rotating field. (Residual voltage measured between
#9 and the 50 hertz leads unplugged from the
capacitor - BCG 4.0KW & BCD 4.4KW: 6 - 8 volts AC;
BCG 6.5KW
&
BCD 6.0KW: 8 - 10 volts AC.) This
residual voltage must be present for the exciter cir-
cuit to function. Do not unplug capacitor leads while
the generator is operating.
An AC voltage can be measured across the
capacitor(s) while the generator is operating. This
voltage may be as high as 450 to 500 volts AC. This
voltage buildup is accomplished as the exciter wind-
ings charge the capacitor(s) and the capacitor(s) dis-
charge back into the exciter windings. This AC
voltage reading is taken between the #50 hertz con-
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nector and the #9 connection between the capacitor(s) while the generator is operating at its rated hertz
(60.5 - 61.5 for gasoline models, and 61.5 - 62.0 for diesel models).
This flow of saturating AC voltage in the exciter windings prod uces a phase-imbalance type of field that
effects the rotating auxiliary windings: A beneficial result that produces good motor starting characteris-
tics for this type of generator.
To measure the resistance value of the exciter windings, locate the #9 and the #50 hertz capacitor con-
nections.
NOTE: Three numbered capacitor connections exist: #7, #8, and #9; and two hertz connec-
tions, #50 and #60.
Unplug any other connections from the capacitor(s) noting their position on the capacitor.
Place one lead of the ohmmeter on plug connection #9 and the other lead on plug connection #50
hertz. Measure the resistance value of the exciter windings. Check to make sure there is no continuity
to the ground/generator case from either of the two leads. Also check that no continuity exist between
either the #50 hertz plug or the #9 plug and any of the main stator winding leads on the AC terminal
block (refer to paragraph B). If continuity is found here, a fault exists between these two winding groups.
205 Westerbeke Generators