Specifications
7.6KW
BT
GENERATOR
SINGLE
PHASE
BRIDGE
RECTIFIER
The bridge rectifier
is
supplied AC voltage from the auxiliary
windings
in
the generator stator
«(::-3)
and the compound
transformer (D-3). The AC voltage measured across the AC
terminals
of
the rectifier during engine operation
is
as fol-
lows:
120
Volts
NIL
FIL
17 - 44 Volts AC
; 120/240
Volts
NIL
FIL
. 17 -
44
Volts
AC
Diodes
in
the rectifier convert this AC voltage to
DC
and
supply it
to
the windings
of
the exciter stator to induce a field
through which the exciter rotor revolves. The
DC
voltage
measured across the
(+) and
(-)
terminals
of
the bridge recti-
fier during engine operation
is
as follows:
120
Volts
120/240
Volts
NIL
FIL
NIL
FIL
(
8 -
17
Volts
DC
: 8 - 17
Volts
DC
Failure
of
the bridge rectifier will result in a weak field being
produced
by
the exciter stator windings. A weak field is pre-
sent, due to the magnetism
in
the exciter stator, which will
cause the generator to produce residual voltage.
BRIDGE
RECTIFIER
POINT
#1
POINT
#4
Testing
The
Bridge
Rectifier
For
Faults
With
An
Ohmmeter
(Meter used: Simpson 260)
1.
Set the ohmmeter scale on
RXI
(+ DC) and set the
needle to zero.
2. Connect the positive
(+) lead from the ohmmeter to point
#4. Taking the ohmmeter's negative
(-)
lead, momentar-
ily contact points #1, #2, #3, and #5. The ohmmeter
should register no deflection for any
of
the points
touched.
3. Remove the positive
(+) lead from point
#4
and connect
the negative
(-)
lead to point
#4
and, with the positive (+)
lead, momentarily touch points #1, #2, and #3. The ohm-
meter's needle should deflect when each point
is
touched,
showing a passage
of
meter voltage through the diodes
in
the rectifier.
4. Leaving the negative
(-) ohmmeter lead on point #4,
touch point #5 with the positive
(+) lead. No deflection
of
the needle should occur.
S.
Place the positive (+) lead
of
the ohmmeter on point # I
and the negative
(-)
lead on point #3. The ohmmeter
should not register any deflection
of
the needle (no
deflection indicates infinite resistance). Reverse these
connections and the ohmmeter should again register
no
deflection.
If
the rectifier fails any
of
the previous tests
(1
-4) it
is
defective and should be replaced.
NOTE:
Different style/model meters may produce opposite
results from the above tests.
Engines & Generators
42