Explain working of Weston type frequency meter.

Explain working of Weston type frequency meter.
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2 Answers

Answer :

Working of Weston Type Frequency Meter:

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The mounting and connections are shown in the figure. Inductor L damps the harmonics in the current. When connected across the supply, coils A and B draw currents to produce magnetic fields that act on the soft iron needle to deflect it. The position of the needle depends on these currents. Under normal frequency (due to proper selection of RA, RB, LA, LB, ) two forces make the pointer to show normal frequency. When the frequency is other than normal, the reactances of LA and LB will be different with resistances unchanged, leading to deflections in either direction depending on the currents there in, due to changed impedances.

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Answer :

Weston Type Frequency Meter: There are two fixed coils marked as A and B. Each coil divided into two equal parts and are fixed such that their magnetic axis are perpendicular to each other. At their center a soft iron needle is placed on spindle to which the pointer is attached. The mounting and connections are shown in the figure. Inductor L damps the harmonics in the current. When connected across the supply, coils A and B draw currents to produce magnetic fields that act on the soft iron needle to deflect it. The position of the needle depends on these currents. Under normal frequency (due to proper selection of RA, RB, LA, LB, ) two forces make the pointer to show normal frequency. When the frequency is other than normal, the reactances of LA and LB will be different with resistances unchanged, leading to deflections in either direction depending on the currents there in, due to changed impedances.

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