TM 5-3895-346-14
REGULATOR
ENGINE OVERHAUL
REGULATOR
AC CHARGING CIRCUIT
The alternating-current generator regulator is similar in outward appearance to the regulator used with the dc
generator. The dc and ac regulators are NOT interchangeable.
The internal wiring circuits of all standard ac generator regulators are similar, but the internal connections vary
somewhat according to the method used to control the circuit breaker relay.
There are two and three unit standard ac generator regulators; the two-unit regulators have a circuit breaker
relay controlled by a relay rectifier or by an oil-pressure switch and the three unit regulators have a circuit
breaker relay controlled by a built-in control relay.
The generator field circuit is insulated in the generator and grounded in the regulator. This type of connection
is designated as Circuit A.
CAUTION
Each type of regulator is used with a certain circuit. Do not attempt to interchange
regulators.
The two-unit ac generator regulator has a circuit breaker relay and a voltage regulator unit while the three-unit
regulator is also equipped with a control relay in addition to the other two units.
CIRCUIT BREAKER RELAY
The circuit breaker relay has a core with the winding made up of many turns of fine wire. This core and winding
are assembled into a frame. A flat steel armature is attached to the frame by a hinge and is centered above
the core. Two contact points, supported by two flat springs on the armature, are located above two stationary
contact points. The upper and lower contact points are held apart by the tension of a flat spring riveted to the
top side of the armature.
Operation
When the dc voltage reaches the value for which the circuit breaker relay is adjusted, the magnetism induced
in the core by current flow in the winding is sufficient to overcome the armature spring tension and the relay
points close. Closing of the contact points connects the dc side of the power rectifier to the battery so that
current will flow to the battery whenever the generator is driven at sufficient speed.
The relay contact points remain closed as long as the dc voltage is enough to hold the relay armature against
the core. They open when the voltage decreases to a value at which the magnetic pull of the core can no
longer overcome the armature spring tension.
VOLTAGE REGULATOR
The voltage regulator unit has a core with a single shunt winding. This winding also consists of fine wire and is
connected across the dc side of the power rectifier. The assembly and parts are similar to the circuit breaker
relay. The matching upper contact point is supported by a detachable contact support insulated from the
frame.
Operation
If the voltage regulator unit is not operating, the generator field circuit is completed to ground through the
contact points which are held closed by the tension of a spiral spring acting on the armature.
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