Operating Principles

Regulator voltage setting varies with temperature and limits system voltage by controlling rotor field current. When the field current is on, the regulator actually switches rotor field current on and off at a fixed frequency of about 400 cycles per second to help control radio noise. 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-off time may be 90 percent and 10 percent respectively.

Generator Schematic:

A basic wiring circuit for the "PLIS" regulator is shown in image. The "P" terminal connects to the stator. The "S" terminal may be connected externally to the battery to monitor voltage and make sure the regulator maintains an adequate voltage level to charge the battery. If the "S" terminal is not connected externally, integrated circuits in the regulator are used for sensing voltage.

Both the "L" and "I" terminals serve to turn on the regulator and allow field current to flow when the switch is closed. The "I" terminal may be connected either directly to the switch, or through a resistor. The "I" circuit may be used with or without anything connected to the "L" circuit and with or without anything connected to the "L" terminal. When used, the "L" terminal must be connected through an external resister, such as the charging system indicator lamp. When a generator fault is detected, (voltage to high or to low, or no rotation), the regulator grounds the "L" terminal and activates the indicator lamp.