Westerbeke 9.0 BCG Technical Manual page 191

1. The amount of no-load voltage produced by the generator can be an indicator of where in the generator
the problemlfault may lie.
Residual Voltage 18 - 22 Volts AC
This voltage is the AC voltage produced by the generator from magnetism in the exciter stator field. This
voltage is measured between the Neutral and Hot leg(s) with no load on the generator, with it running at
rated rpm.
The presence of residual voltage is an indication that the following generator components are OK
1. Exciter Rotor (B-1)
2. Rotating Field (B-3)
3. Main Stator (C-1 & 2)
4. Compound Transformer (0-1 &2)
The fault lies in one or more of the following components in the exciter circuit:
A. Exciter Stator (A-1 & 2)
B. Bridge Rectifier (G)
C. Selector Switch (F)
o.
Main Stator Auxiliary Windings (C-3)
E. Compound Transformer Auxiliary Winding (0-3)
2. Twelve (12) volt DC excitation of the exciter stator windings with the selector switch in COMP should cause
the generator to produce between 125 - 135 volts AC between each hot lead and the neutral. (Twelve
volts DC is applied between the lifted (+) and (-) leads of the bridge rectifier, + to + and - to - .) Cor-
rect voltage produced with twelve volts DC excitation indicates the fault is in one or more of the above
listed components B, 0 or E. If the generator does not produce 125 - 135 volts AC, then include A and C.
The following is a list of faults with the generator operation on compound (COMP) transformer regulation.
(No A.V.R. installed)
FAULT
Correct voltage at
NIL and loss of voltage
as load is applied.
(No loss of engine speed
and hertz.)
High voltage at NIL
125 -135 volts with
correct voltage 115 - 120
at FIL.
High voltage at NIL
and FIL.
CAUSE
1. Selector switch
in wrong position.
1. Generator's engine
speed (rpm) high
at NIL.
1. Generator's engine speed
(rpm) is too high.
185
CORRECTION
1. Place selector switch
in COMP position.
1. Check NIL speed and
adjust voltage.
1. Check NIL rpm and
adjust NIL voltage
Westerbeke Generators