Testing Exciter Windings; Testing The Capacitor - Westerbeke 5.0Kw BCDR Operator's Manual

5.0KW BC GENERATOR SINGLE PHASE
Ballast Resistor 0.5 Ohm
Early model integral controllers have a ballast resistor
installed along the DC positive (+) lead running from the
bridge rectifier to the integral controller. This coil-type resis-
tor functions to suppress high amperage draw coming from
the controller when it is trying to charge a discharged starting
battery.
BALLAST RESISTOR
Early controllers having this resistor in the DC charging cir-
cuit are of the three lead type. These three lead types consist
of either three spade plugs in connections or consist of three
wire leads from the controller.
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50
60 7 8
91
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fC~PACITO~Sf
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TESTING THE EXCITER WINDINGS
Single
Capacitor
1.9 Ohms
Dual
Capacitor
2.2 Ohms
Dual
Exciter
1.3 Ohms
An AC voltage is induced in these windings by the rotating field.
Checking the residual voltage output from this winding can
determine the condition of the winding when troubleshooting.
RESIDUAL VOLTAGE:
Single Capacitor Model:
Dual Capacitor Model:
Dual EIcHer Model:
10 -14 Volts AC from each winding
14 -16 Volts AC from each winding
7 - 9 Volts AC from each winding
AC voltage can be measured across the capacitor(s) while the
generator is operating. This voltage may be as high as 400 to
500 volts AC. This voltage buildup is accomplished as the
exciter windings charge the capacitor(s) and the capacitor(s)
discharge back into the exciter windings. This AC voltage
reading is taken between the #60 Hertz connector and the #
connection plugged into the capacitor(s) while the generator
is operating at its rated Hertz
(61.5 - 62.0).
This flow of satu-
rating AC in the exciter windings produces a phase-imbal-
ance type of field that effects the auxiliary windings: a
beneficial result that produces good motor starting character-
istics for this type of generator.
To measure the resistance value of the exciter windings,
locate the #9 and the #50 Hertz capacitor connections.
NOTE: Three numbered capacitor connections exist: #7, #8,
and #9,. and two Hertz connections, #50
and
#60.
Unplug any other connections from the capacitor(s) noting
their position on the capacitor. Place one lead of the ohmme-
ter on plug connection #9 and the other lead on plug connec-
tion #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 exists between either the #50 Hertz
plug or the #9 plug and any of the main stator windings leads
on the AC terminal block. If continuity is found here, a fault
exists between
the~e
two winding groups.
FIELD TESTING
CAPACITORS
FIELD· TESTING THE CAPACITOR
With a capacitor meter, test the capacitor following the
instructions included with the meter, and compare the results
with the value shown on the capacitor. When a capacitor
meter is not available, perform the following simple test:
1. Marking them so they may be reattached correctly,
unplug the connections from the capacitor.
2. With a jumper, short across the two connections exposed
in the previous step. This ensures the capacitor is dis-
charged as it would be at shutdown.
. 3. With an ohmmeter
~et
on the high R scale, place its plus
(+) lead on one capacitor connection and the negative (-)
lead on the other capacitor connection. A resistance
should be read and should rise slowly as the meter
attempts to charge the capacitor. This indicates a presum-
ably good capacitor.
4. Indications of a defective capacitor:
a. Zero resistance or no rise in resistance value (shorted
capacitor).
b. Infinite resistance (open capacitor).
c. No continuity should be found between the capacitor's
connections and the capacitor's case or base.
s.
Capacitor Ratings (Capacitor meter)
a. Single Capacitor Units: 25.0 microfarads (uF) 5°
b. Dual Capacitor Units:
31.5
microfarads
(uF)
5°
NOTE: Ratings are found on the capacitor case.
NOTE:
The older single capacitor models used a 25.0
microfarad capacitor. All new model single capacitor
units now have a
31.5
microfarad capacitor. When
replacing a capacitor in either an early model or a later
model, ensure that the correct rated capacitor is
installed. The capacitor rating is marked on the housing
of the capacitor:
25.0 Microfarad capacitor PN 035985
31.5 Microfarad capacitor PN 035978.
Engines & Generators
51