DETROIT DIESEL 53
BATTERY-CHARGING GENERATOR REGULATOR
A.C. CHARGING CIRCUIT
The alternating current generator regulator is similar in outward appearance to the regulator used with the D.C.
generator. The D.C. and A.C. regulators are NOT interchangeable.
The internal wiring circuits of all standard A.C. 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 A.C. 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".
NOTE: Each type of regulator is used with a certain circuit. Do not attempt to interchange regulators.
The two unit A.C. 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.
When the D.C. 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 D.C. 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 D.C. 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.
The voltage regulator unit has a core with a single shunt winding. This winding also consists of fine wire and is
connected across the D.C. 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.
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.
When the D.C. voltage of the A.C. - D.C. system reaches the value for which the voltage regulator is adjusted, the
magnetic field produced by the shunt winding overcomes the armature spring tension and pulls the armature down,
causing the contact points to separate. When the contact points separate, resistance is introduced into the field circuit.
The resistance decreases the field current causing a corresponding decrease in generator voltage and magnetic pull on
the regulator armature. This allows the armature sprang tension to re-close the contact points. When 'the voltage again
reaches the value for which the voltage regulator is adjusted, this cycle repeats and continues to repeat many times a
second, thus limiting the voltage to the value for which the regulator is set.
With the voltage limited in this manner, the generator supplies varying amounts of current to meet the various states of
battery charge and electrical load.
Voltage regulators are compensated for variations in temperature by means of a bi-metal thermostatic hinge on the
armature. The effect of this hinge causes the regulator to adjust at a higher voltage when cold. which partly
compensates for the fact that a high voltage is required to charge a cold battery.
May, 1971 SEC. 7.1.1 Page 3