Testing The Diodes; No-Load Voltage Adjustment; Ac Hertz Conversion - Westerbeke 6.5 MCG Service Manual

BC GENERATOR SINGLE PHASE
TESTING THE DIODES
Carefully unsolder the thin connection to the diode and
remove the diode using a then walled, deep well7/16"
(llmm)
socket and a box wrench as needed.
Test the diode as shown with ohmmeter leads at both ends,
then re~erse the positions
A low resistance should be found with the leads in one
direction and infinate resistance (blocking) in the other
direction.
DIODES: 1.4- 1.5 OHMS (APPROX)
USING A 260 FLUKE 76 METER
Note that different meter models
may
show different ohm
values, but should read the same for both diodes.
DIODES RATING 1600 VOLTS 26 AMPS
The diode's rating is far in excess of the circuit's
requirements. Most likely a diode failure will result from
a generator overspeed or load surge.
NO·LOAD AC VOLTAGE OUTPUT ADJUSTMENT
No-load AC voltage output can be adjusted up or down using
one of the three numbered taps #7, #8, or #9. Moving up in
the number sequence increases circuit excitation and
increases AC output and the reverse when moving down ·
the numbered sequence.
The #60 or #50 is plugged into one connection on the circuit
capacitor
to
correspond to the hertz the unit is operating at.
Either the #7, #8, or #9 can be plugged into the second
connection. This connection on each exciter circuit's
capacitor does not have to be the same for both. One circuit
can have a #7 plugged into its capacitor and the other circuit
a #9. Whatever combination gives the best No-Load AC
output sought after. The un-used connector ends must be
covered and tied off.out of harms way.
A
CAUTION:
Make all connection changes with the
generator not operating as high AC voltage is present in
these .circuits while the generator is operating.
AC/HERTZ CONVERSION
The MCG model BC style generators can be converted from
60 hertz 120 volt output to 50 hertz 230 volt output by
following these procedures.
1. Tum OFF the AC breaker and the DC breaker on the
Control Box. Open the Control Box on the generator.
This will give you access to the AC output winding
connections, Exciter Circuit connections and Battery
Charge Circuit connections. All of which will need
connection changes.
2. Reference the AC output configuration drawing below and
configure the output leads as shown. AC circuit breaker
may need to be replaced with a different rating. Breaker
listing is below. Be sure to properly position the
Neutral to Gen. frame wire (white/green). Failure to do
so will result in a severe electrical short in the main stator
windings.
1
4 AC TERMINAL CONNECTIONS 1 6
CIRCUIT
BREAKER
2
CIRCUIT
BREAKER
ISOLATED
POST
120V60Hz
L1
230V50Hz
AC BREAKERS
5.0/4.2 MCG #042232
6.5 MCG #038798
5.2 MCG #042713
3. At the two excitor circuit capacitors, change the hertz
connection on each either #50 to #60 or #60 to #50.
4. At the Battery Charge circuit, the hertz connection on the
circuit's bridge rectifier needs
to
be changed to either the
#50 or the #60 to correspond to the hertz selected
5. The above completed, the ECU must be reprogrammed to
the hertz selected. Refer to Setting/Changing Engine
Speed (Hertz) discussed in this manual.
FUSE PROTECTION
Four DC circuit protectors are found in the engines electrical
circuit. A 15 amp DC breaker and an 8 amp buss fuse on the
control panel. A 30 amp buss fuse in the control panel and a
30 amp spade fuse by the starter motor for the battery charge
circuit.
BATTERY CHARGING CIRCUIT
EXCITER CIRCUIT
WITH DUAL CAPACITORS
EXCITER CIRCUIT CAPACITORS
5.0/4.2 MCG #046875
~
6.5MCG#049627
~
I I . l . . 1
J
5.2 MCG #046639
FUSE·
INTEGRAL CONTROLLER
WfNDfNG: NO TtME DELAY
Pn/43634 30A
250V
MDA-30
50HZ 60HZ
• •
7 8. 9 •••
9 \
s.·
7 60HZ 50HZ
• • • • •
(·)
50Hz
Engines & Generators
71