Description & Operation: Generator

The Delco-Remy CS charging system has several models available, including CS-121D. Number denotes outer diameter in millimeters of stator lamination. CS generators are equipped with internal regulators. A Delta stator, a rectifier bridge, and a rotor with slip rings and brushes are electrically similar to earlier generators. A conventional pulley and fan are used. There is no test hole. Unlike three-wire generators, CS-121 D may be used with only two connections: battery positive and an "L" terminal to charge indicator lamp. Use of "P," "I," and "S" terminals is optional. "P" terminal is connected to stator and may be connected externally to a tachometer or other device.

Charge indicator lamp lights when ignition switch is turned to ON, and goes out when engine is running. If charge indicator is on with engine running, a charging system defect is indicated. This indicator light will glow at full brilliance for several kinds of defects, as well as when system voltage is too high or too low. Regulator voltage setting varies with temperature and limits system voltage by controlling rotor field current. regulator switches rotor field current on and off at a fixed frequency of about 400 hz. By varying on-off time, correct average field current for proper system voltage control is obtained. At high speeds, on-time may be 10 percent and off-time 90 percent. At low speeds, with high electrical loads. on time may be 90 percent and off-time 10 percent.