Subaru Robin Power Products R1200 service manual Voltage Regulation Under Load

5-2 DESCRIPTION OF GENERATING OPERATION

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Magneto

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5-2-l GENERATION OF NON-LOAD VOLTAGE

When the generator starts turning, the permanent magneto incorporated in the flywheel in the engine side starts rotating, which generates voltage in the exciting coil. The voltage, rectified by the diodes in the AVR, causes the flow of the current @through the field coil wound around the rotor in the generator. The rotor is then turned to an electromagnet by the current and at the same time when it starts rotating, voltage is generated in the coils (main coil, sub-coil, and DC coil) of the stator. -Then,the voltage generated in the sub-coil is rectified by the AVR, and the current @ flows so that current in the field coil is increased. This increases magnetic intensity to the rotor. Rated voltage is generated in the main coil and the DC coil by repeating this operation.

5-2-2 VOLTAGE REGULATION UNDER LOAD

When a load is connected to an AC receptacle and current is increased, output voltage fluc- tuates and the voltage fluctuations in the case where an AVR is in the circuit and in the case where no AVR is in the circuit differ as shown in Fig. 5-2-2. The AVR operates as follows.

When AC output is taken out, load is put on the engine. The AC voltage becomes lower because rpm of the engine becomes fewer and the voltage decreases on account of inner resistance of the coil. The AVR detects the voltage decrease and automatically increases the current flowing through the field coil with a thyrister inside the AVR. As a result, magnetic intensity to the rotor is increased while the decreased voltage is raised again by taking out loaded current, which in turn main- tains the output voltage at a constant level. When the AC output becomes lower the thyris-

ter provides reverse operation, and in this case, the voltage is also maintained at a

constant level.

Rated Level

Current (A)

F& 5-2-2

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