Question 114Electricity & Electronics - 1st Asst/Chief

70% to pass

When a self-excited DC generator's field has lost its residual magnetism due to a prolonged idle period, it will fail to produce a voltage. Flashing the field is the procedure used to restore the residual magnetism. Using a 12 volt storage battery, how is this performed?

AThe A1 and A2 leads are disconnected from the generator. The A1 lead is connected to the positive terminal of the battery, and the A2 lead is connected to the negative terminal.

BThe S1 and S2 leads are disconnected from the generator. The S1 lead is connected to the positive terminal of the battery, and the S2 lead is connected to the negative terminal.

CThe F1 and F2 leads are disconnected from the generator. The F1 lead is connected to the positive terminal of the battery, and the F2 lead is connected to the negative terminal.

DThe F1 and F2 leads are disconnected from the generator. The F1 lead is connected to the negative terminal of the battery, and the F2 lead is connected to the positive terminal.

AI Explanation

The correct answer is C. To restore the residual magnetism in a self-excited DC generator whose field has lost its magnetism, the field windings (F1 and F2 leads) need to be connected to a 12V battery. By connecting the F1 lead to the positive terminal and the F2 lead to the negative terminal of the battery, a current will flow through the field windings, re-magnetizing the field and allowing the generator to produce a voltage. The other options are incorrect because they involve connecting the wrong leads to the battery terminals, which would not effectively restore the residual magnetism in the generator's field.

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