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A.C. POTENTIOMETER. Its principle is same as a But in an a.c. potentiometer, not only the magnitudes but phases as well DRYSDALE POLAR TYPE AC. Posts about polar type ac potentiometer written by Pragnarongali. The working principle of the AC potentiometer is same as that of the DC potentiometer, i.e., the unknown voltage is determined by Polar Type Potentiometer.

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The instrument is balanced by the main dial and the slide wire, drysdqle the protective resistance again in the circuit. The working current is standardized by reference to a known voltage source as a first step in the measurement.

Where as, AC potentiometer measures both the magnitude and phase of unknown voltage by comparing it with known reference. Measures voltage as magnitude and phase from reference voltage. Web Design by Pure Energy. The single range potentiometer can be modified to include a second measuring range of lower value by adding two range resistors and a range switch.

C potentiometer is an accurate and versatile instrument and thus it is obvious that the potentiometer principle can be applied to measurement of alternating currents and voltages.

Further references can be found at: Polar type Potentiometer In such type of instruments, two separate scales are used to measure magnitude and phase angle on some reference of the unknown e.

Join our Mailing List by adding your email address below and drysdalf kept up to date with lots of information including:. To find out more, including how to control cookies, see here: The known voltage may be supplied by a standard cell or any other known voltage-reference source.

Since opening at the end ofover 5, children have visited drysrale Centre. In order to operate the galvanometer at its maximum sensitivity, provision is made to short the protective resistance when near the balance conditions. The phase-shifting transformer is usually supplied by single-phase current.

Drysdale’s Alternating and Continuous Current Potentiometer – Computing History

The basic principle here is measuring an unknown voltage by comparing it with known voltage. Voltmeter Calibration — The AC potentiometer directly measures the low voltages up to 1. By continuing to use this website, you agree to their use.


Hence the value of the unknown emf is known. The rotor has a rrysdale on it which supplies the potentiometer current. It also supplies 6 volts to potentiometers. 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.

In these instruments, the magnitude of the unknown voltage is read from one scale and its phase angle, with respect to a.c.potentimoeter reference phasor, is read directly from a second scale. The method of measuring unknown voltage E depends on finding a position for the sliding contact such that the galvanometer shows zero deflection when galvanometer key K is closed. There is a provision on the scale that it could read phase angle up to The 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.

Drysdale ac polar potentiometer

This potentiometer is provided with a double throw switch which allows the connection of either the standard cell or the unknown emf to be applied to the working circuit. As zero deflection is approachedthe protective resistance is shorted and final adjustments are made with the rheostat control. Please be assured that any amount you feel able to donate will make an immediate and significant impact.

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.

There is one dial switch with 15 steps, each having a precision resistor. These children deserve a space which is engaging and instructive, where they can feel a sense of adventure, exploration drjsdale surprise! The slide wire type of potentiometer is not a practical form of construction. Join our Mailing List by adding your email address below and be kept up to date with lots of information including: Drysdale’s Alternating and Continuous Current Potentiometer The instrument comprises the standard Tinsley DC potentiometer of the time, with a phase shifter, Weston dynamometer voltmeter, selection and change-over switches and terminal panels for connection of galvanometers, DC and AC measuring and supply voltages.


The value o the unknown voltage is read directly off the dial settings. The AC potentiometer may be broadly classified as.

Tag: polar type ac potentiometer

These instruments are provide with two scales to read respectively the inphase component V1 and the quadrature component V2 of the unknown voltage V. This principle of operation of all potentiometers is based on the following basic circuits. 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 known source may be DC or AC. Other Applications — The AC potentiometer is used for engineering measurement in which the accuracy of 0. The most important difference between a d. 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. The indicator for low frequencies is a vibration galvanometer which must be closely tuned to resonate to the frequency of the circuit.

Thus, the voltage and current may vary at different power factor. Applications of AC Potentiometer Measurement of self-inductance. The phase shifting transformer is connected to the potentiometer a.c.potentoimeter vary the phase of the voltage on the current.

The operation of the AC potentiometer is quite complicated as compared to the DC potentiometer.

Between the stators, there is laminated rotor having slots and winding which supplies voltage to the slide-wire circuit of the Potentiometer. This is done by switching it over on to a continuous current circuit, which is adjusted until a balance is obtained at the proper setting, when a Weston cell is connected up in the polaf manner.

Leave a Reply Cancel reply Your email address will not be published. The AC potentiometer is also used for measuring the voltage which must be resolved into two components. This ammeter must read correctly with alternating and continuous currents.