Hay’s Bridge method of measurement is particularly suited for the measurement of inductance having high Q Values. Figure 1: Hay’s Bridge.
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Maxwell’s Bridge method is used for measuring an unknown inductances of low Q values. It measures unknown inductance in terms of known capacitance. The circuit of Maxwell’s bridge is shown in Fig. 1. One arm of the bridge has resistor R1 in parallel with capacitor C1. The unknown inductor Lx with series resistor Rx is
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Figure 1: PMMC Instrument. Working Principle of PMMC Instrument When a current carrying conductor is placed in a magnetic field the force is produced on the conductor (coil). This force tends to move the coil in the space. Construction of PMMC Instrument Fig. 1 shows constructional details of PMMC instruments with different constructions of permanent
DC voltmeter like PMMC meter works on DC supply but this meter can work on AC supply as if it is a AC voltmeter. Figure 1. What is required is an additional device to be connected between AC supply and PMMC meter is a Rectifier unit. If single diode is used as a rectifying unit for
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The deflecting torque causes the pointer to deflect from zero position and it may attain any position on the scale. But it is desired that the proportional to the quantity attain any position deflection should to be measured. So controlling torque is essential.
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The eddy current tachometer converts the angular speed (ω) of the rotor into pointer deflection ϕ. The diagram of the eddy current type tachometer is shown in figure 1. The eddy current tachometer is also referred as drag-up tachometer.
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