Electrical Engineering Study Material

Wattmeter

The wattmeter is an instrument which measures DC power or true AC power. The wattmeter uses fixed coils to indicate

The ohm meter is an instrument used to determine resistance. A simple ohm meter (Below Figure) consists of a battery,

The ammeter measures electric current. It may be calibrated in amperes, milliamperes, or microamperes. In order to measure current, the

A simple DC voltmeter can be constructed by placing a resistor (RS), called a multiplier, in series with the ammeter

The moving iron vane movement (Figure 1) can be used to measure both AC current and voltage. By changing the

The electrodynamometer movement (Figure 1) has the same basic operating principle as the D’Arsonval meter movement, except that the permanent

The most commonly used sensing mechanism used in DC ammeters, voltmeters, and ohm meters is a current-sensing device called a

Transformers are constructed so that their characteristics match the application for which they are intended. The differences in construction may

The symbol for a transformer gives no indication of the phase of the voltage across the secondary. The phase of

If the secondary of a transformer is left open-circuited (Figure 6), primary current is very low and is called the