Principles of Operation: Functionality

In the single generator system, with the key in the ON position, voltage is applied through the charging system warning indicator I circuit to the voltage regulator. This turns the voltage regulator on, allowing current to flow from the battery sense A circuit to the generator field coil. When the engine is started, the generator begins to generate alternating current (AC) which is internally converted to direct current (DC). This current is then supplied to the electrical system through the output terminal (B+) of the generator.

Once the generator begins generating current, a voltage signal is taken from the generator stator and fed back to the voltage regulator through the stator circuit 4 (WH/BK). This voltage feedback signal (typically one-half of the battery voltage) is used to turn off the charging system warning indicator on the single generator system. The gas engines have an external stator circuit and the diesel engines have an internal stator circuit.

With the system functioning normally, the generator output current is determined by the voltage of the A circuit 35 (OG/LB). The A circuit voltage (battery sense circuit) is compared to a set voltage internal to the voltage regulator. The voltage regulator controls the generator field current to maintain the correct generator output.

The set voltage varies with temperature and is typically higher in cold temperatures than in warm temperatures. This allows for better battery recharge in the winter and reduces the chance of overcharging in the summer.

The single generator system consists of the generator mounted on the top right of the engine (diesel) or top center of the engine (gas). The gas engines use a 3G 115-amp generator with a 2.52:1 ratio and an extra heavy-duty option that includes a 6GLF 135-amp generator with a 2.52:1 pulley ratio. The 6.0L diesel engine uses a 110-amp standard generator with a 2:79 pulley ratio and an extra heavy-duty option is available that includes a 140-amp generator with a 2.79:1 pulley ratio.