The Potentiometer is an instrument which measures unknown voltage by balancing it with a known voltage. The known source may be DC or. Definition of DRYSDALE POTENTIOMETER: An ac potentiometer of the polar type, comprising a phase-shifting transformer and resistive voltage divider. Definition: The potentiometer which is used for measuring the phase and the magnitude of the unknown emf by comparing it with the known emf such type of.

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A rotation of the rotor of the phase-shifting transformer through o has the effect of producing a phase shift of the same value, and a pointer on the rotor axis indicates the phase angle on a suitably divided scale.

What is AC Potentiometer? Definition, Types & Applications – Circuit Globe

Voltmeter Calibration — The AC potentiometer directly measures the low voltages up to 1. Your email address will not be published. The whole arrangement of the winding is done in such a way that the magnitude of the induced emf in the rotor may change but it does not affect the phase angle and it can be read on the scale fixed on the top of the instrument.

Drysdale for the measurement of alternating potentials. Hence the value of the unknown emf is known. The AC potentiometer may be broadly classified as.

Leave a Reply Cancel reply Your email address will not be published. One is directly connected to power supply and the other one is connected in series with variable resistance and capacitor. It also supplies 6 volts to potentiometers. The function of the series components is potejtiometer maintain constant AC supply in the potentiometer by doing small adjustments in it. Where as, AC potentiometer measures both the magnitude and phase of unknown voltage by comparing it with known reference.


To obtain the necessary field distribution a split-phase scheme is used, part of the excitation being provided by a circuit containing a condenser and a resistance in series.

The main circuit of the potentiometer must be supplied with alternating current of exactly the same frequency as that in the circuit to be measured, which means in practice that they must be supplied from the same source.

Thus, the voltage and current may vary at different power factor.

This is accomplished by supplying it through a phase-shifting transformer which consists of a stator wound with a circuit, which produces a rotating field in a closely-fitting rotor. The AC potentiometers are classified by the value measured by the potentiometer dial and scales.

AC Potentiometers

It gives the accurate results in magnetic testing and precise testing of instrument transformers. Further, the phase relation between the circuit to be measured and that supplying the potentiometer may have any value from to Thus, the resultant voltage of the coordinate AC potentiometer is And the phase angle is given by.

Potenitometer following are the important factor which must be considered for their operation. The coordinate type potentiometer has two scales to read the inphase V 1 component, and the quadrature component V 2 of the unknown voltage V. The main potentiometer current must be kept at some known constant value.


For higher frequencies a telephone may be used. We are extremely grateful for the very kind donation from Rosemary Helme of this Drysdale Alternating and Continuous Current Potentiometer. In a phase-shifting transformer, there is a combination of two ring-shaped laminated steel stators connected perpendicularly to each other as shown in the figure. Now the in-phase component V A of the unknown e.

There are two step-down transformers T 1 and T 2 which isolate potentiometer from the line and give an earthed screens protection between the winding. When current start flowing from stators, the rotating field is developed drysdake the rotor and due to it e.

Connects Facebook Youtube Videos. Click on the Images For Detail. Dryssale phase displacement of the rotor emf is equal to rotor movement angle from its original position and it is related to the stator supply voltage.

These children deserve a space which is engaging and instructive, where they can feel a sense of adventure, exploration and surprise! Coordinate type Potentiometer In coordinate AC potentiometertwo separate potentiometers are caged in one circuit as shown in the figure.

There is potentio,eter provision on the scale that it could read phase angle up to Calibration of watt meter.