time. The relay contacts are made of
(6) The reverse current relay located on the
silver and should not require cleaning or
right side of the panel is used to connect
dressing.
the auxiliary generator across the battery
when the generated voltage reaches a
(3) If the relay contacts are changed or
predetermined value and to remove the
replaced at any time, they should be
auxiliary generator from the battery circuit
carefully set.
when the engine speed falls to a value so
e. Putting the Relay in Service. Before putting in
low that the regulator can no longer
service, test as follows:
maintain the proper voltage, as when the
(1) Be sure the battery and generator are
engine is shut down. The relay carries the
both connected with the same polarity.
auxiliary generator current through its
(2) Insulate the contacts of the A contactor.
contacts. The contacts are sufficiently
(3) Start the engine and close the auxiliary
large to carry full current without
generator cutout breaker.
overheating.
(4) Measure the voltage from N to AG. This
(7) The coil of the reverse current relay is
should be about 37 volts.
wound in two sections; a shunt section
(5) Measure the voltage between the contacts
and a series or current section. The shunt
of the A contactor. This should be 5 or 6
coil of the reverse current relay is
volts. If it is 60 or 70 volts, it indicates
connected in series with a ballast resistor
that either the generator or the battery is
across the generator voltage. When the
connected with the wrong polarity.
voltage rises to the pull-in setting, the
relay closes and connects the auxiliary
(6) If the preceding tests show that all is
generator to the battery and load. The
clear, remove the insulation from the A
load current through the relay series coil
contactor. Stop and start the engine
aids in holding the relay closed.
several times while observing the
operation of the reverse current relay to
(8) When the engine stops, the auxiliary
be certain it is operating properly.
generator tries to motor from the battery.
f. Adjustment and Setting.
This reverses the current through the
series coil which then opposes the shunt
(1) Check panel wiring and lettering against
coil and causes the relay to open, which in
turn disconnects the auxiliary generator
(2) Check the resistance of coils and resistor
from the battery and load.
tubes. The regulator coil resistance is 4.5
c. Relay Armature and Contacts. The relay has a
ohms at 25 C. The shunt section of the
clapper-type armature with a rocking pivot which is
reverse current relay coil has 18.8 ohms
practically friction-free. The armature is held in position
resistance.
Resistor tube values are
by the same compression spring which provides part of
shown on the diagram.
the calibration. A brass residual button on the end of
(3) With 37 volts across AG to N (make AG
the iron core maintains the proper magnetic gap when
positive), adjust regulator spring so
the armature is closed. The moving contact is a bridge
contacts float. Coil must be warm. The
which connects two stationary contacts when the
change in voltage to move the movable
armature closes. The stationary contacts are threaded
contact from the right hand stationary
studs to permit adjustment. All contact surfaces are
contact to the left hand stationary contact
silver.
must not exceed 1/2 volt. When making
d. Inspection.
this adjustment, be sure the stationary
contacts are adjusted so that the lower
(1) Inspection of the regulator panel consists
edge of the armature overlaps the frame
largely of a visual inspection to make sure
1/8 inch and the contact gap is 1/16 inch.
that all parts are in proper working order.
All points of the contact surfaces must
Changes in adjustments without good
make contact, simultaneously.
cause should not be made.
(4) Regulator auxiliary panel should hang
(2) The reverse current relay will normally
parallel to the main regulator panel and
require no attention for long periods of
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