VOLTAGE REGULATOR - TM-10-3930-607-150104

ELECTRICAL

There are two units included in the alternator regulator:

increases, the alternator output increases enough to

(1) Voltage regulator, (2) Field relay. In the following

magnetize the armature of the ADLO relay and open the

procedures, each is considered separately.

normally closed contacts; the solenoid is de-energized

and the starter disengages. As the alternator output

B. VOLTAGE REGULATOR

increases further, the reduced-field-voltage contacts of

the regulator are opened and full battery voltage is

Three checks and adjustments are required on the

applied through regulator terminal 3 to the alternator

double contact voltage regulator unit: (1) point opening,

field, and to ground.

(2) air gap, and (3) voltage setting.

As the speed of the alternator increases, the voltage at

1. Point Opening: With the lower contacts touching,

the "BAT" terminal of the alternator also increases. This

measure the point opening between the upper contacts.

impresses a higher voltage through the field relay

Adjust by bending the upper contact arm, being careful

contacts and across the voltage regulator shunt winding.

not to bend the hinge. (Fig. 20)

The increased magnetism created by the higher voltage

across the winding causes the lower contacts to

separate, and field current then flows through a resistor

resulting in reduced field current. This reduced field

current causes the charging voltage to decrease, which

decreases the magnetic pull of the voltage regulator

shunt winding. The spring causes the contacts to close,

and the cycle then repeats many times per second to

limit the charging voltage to a pre-set value. As the

alternator speed increases even further, the resistor

connected across the contacts is not of sufficiently high

value to maintain voltage control on the series contacts.

Therefore the voltage increases slightly causing the

upper or shorting contacts to close. When this happens,

the alternator field winding is shorted and no current

passes through the winding. With no current in the field

winding, the charging voltage decreases. Also, the

magnetism in the shunt winding decreases and the

upper or shorting contact points open. With these points

open, field current flows through the resistor and the

field winding. As the voltage increases, the contacts

close. This cycle then repeats many times per second

to limit the charging voltage to a pre-set value at high

generator speed.

The voltage regulator unit thus

Figure 20.

operates to limit the value of charging voltage

throughout the alternator speed range. Consequently

2. Air Gap: Measure the air gap with a feeler gauge

the electrical accessories are protected from too high

placed between the armature and core when the lower

voltage which would damage them.

contacts are touching. To adjust the air gap, turn the

nylon nut located on the contact support. (Fig. 21)

B-67