Alternator: Description and Operation

This vehicle uses a CS130D generator. The CS130D generator uses a built-in regulator with fault detection, a delta stator, a rectifier bridge and a rotor with slip rings and brushes. Dual internal fans are used to cool the slip ring and drive end frames, rectifier bridge and voltage regulator.

This generator uses at least two wire connections and a ground path through the mounting bracket for operation. The battery positive "BAT" terminal must be connected to a battery during operation. The second required connection is through the indicator lamp or suitable external resistor to the "L" terminal of the regulator. Both connections are necessary to turn the unit on at start-up.

Three other regulator terminals are available for optional use in vehicle systems. The "P" terminal is connected to the stator and may be connected to a tachometer or other device. On Pontiac vehicles the "I/F" terminal provides an alternate method for turning on the generator without going through the indicator light or external resistor, and is often used in parallel with the "L" terminal connection. On Buick vehicles the "I/F" terminal is connected internally to the field and may. be monitored by the PCM for system control. The "S" terminal may be used to sense electrical system voltage somewhere else on the vehicle for voltage control. If the "S" terminal is not used, the regulator uses an internal voltage sense for control.

The regulator is temperature compensated, and limits the system voltage by controlling rotor field current. To control radio noise, the field current is switched on and off at a fixed frequency of about 400 cycles per second while the field circuit is, By varying the on-off time, correct average field current is obtained to provide the proper system voltage. At high speeds, the on-time may be 10 percent and the off-time 90 percent. At low speed with high electrical loads, on-time may be 100 percent.