Charging System: Description and Operation

Fig. 1 Delcotron Type CS-130 & CS-144 Alternators:

The CS charging system has several sizes available, including the CS-121, CS-130 & CS-144 alternators. The number (121, 130 or 144) denotes the outside diameter in millimeters (mm) of the stator laminations.
CS generators use a new type regulator and a diode trio is not used. A delta stator, rectifier bridge, and rotor with slip rings and brushes are electronically similar to earlier generators. A conventional pulley and fan is used and, on the CS-130, an internal fan cools the slip ring end frame, rectifier bridge and regulator.
Unlike three wire generators, the CS generators may be used with only two connections, battery positive and an "L" terminal to the charge indicator bulb.
Use of the "P", "F", and "S" terminals is optional. The "P" terminal is connected to the stator, and may be connected externally to a tachometer or other device. The "F" terminal is connected internally to field positive, and may be used as a fault indicator. The "S" terminal may be connected externally to a voltage, such as battery voltage, to sense voltage to be controlled.
As on other charging systems, the charge indicator lights when the switch is closed, and goes out when the engine is running. If the charge indicator is on with the engine running, a charging system defect is indicated. For all kinds of defects, the indicator will be on with the engine running if system voltage is too high or too low. The regulator voltage setting varies with temperature, and limits voltage by controlling rotor field current.
This regulator switches rotor field current on and off at a fixed frequency of about 400 cycles per second. By varying the on-off time, correct average field current for proper system voltage control is obtained. At high speeds, the on time may be 10% and the off time 90%. At low speeds, with high electrical loads, on and off time may be 90% and 10%, respectively.
No periodic maintenance on the generator is required. The CS-121 and CS-130 are not repairable and may only be replaced as a single unit. The CS-144 is repairable.