Question

The phase displacement of the rotor emf in Drysdale potentiometer being equal to

• A. Angle of rotor from zero position
• B. Angle of rotor
• C. Angle of the slide wire
• D. Angle of rotor with reference to stator coil

Hint:

AC Potentiometers (Polar Type). Drysdale potentiometer measures AC voltage magnitude and phase. Phase adjustment is done by physically rotating a rotor coil within a stator field; the phase shift is proportional to the rotor's angular position.

Answer 1

The Correct Option is A

The Drysdale polar AC potentiometer works by comparing an unknown AC voltage with a known reference voltage that can be varied in both magnitude and phase
The phase variation is typically achieved using a phase-shifting arrangement, often involving a stator providing a rotating magnetic field and a rotor coil whose induced EMF phase depends on its mechanical angle relative to a reference position
The magnitude is adjusted using a standard AC potentiometer circuit (slide wire)
The phase of the reference voltage (rotor EMF) is directly controlled by and proportional to the angular position of the rotor relative to its calibrated zero phase position on a circular scale
Therefore, the phase displacement is equal to the angle of the rotor from its zero reference position