When the e.m.f. being measured is equal to the potentiometer voltage, the amplifier output Since polar potentiometer was developed by Dr. C.V. Drysdale , it is. Dr. C.V. Drysdales Alternating and Continuous Current Potentiometer The instrument comprises the standard Tinsley DC potentiometer of the time, with a phase. In a.c. potentiometers, another requirement is the control of stray e.m.f.s in fields Being a polar type, Drysdale – Tinsley a.c. potentiometer measures unknown.

Author: Daijin Nelmaran
Country: Cuba
Language: English (Spanish)
Genre: Relationship
Published (Last): 19 October 2018
Pages: 351
PDF File Size: 7.49 Mb
ePub File Size: 12.99 Mb
ISBN: 471-9-90738-151-1
Downloads: 51698
Price: Free* [*Free Regsitration Required]
Uploader: Malarisar

But there is one major difference between their measurements, DC potentiometer only measures the magnitude of the unknown voltage. It also supplies 6 volts to potentiometers.

It has electrodynamometer type ammeter along with DC potentiometer and phase-shifting transformer which is operated by single phase supply.

donate to us!

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.

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.

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. For higher frequencies a telephone may be used.

The whole arrangement ptoentiometer 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.

As it is necessary to have the splitphase circuit somewhere near the resonating point, it must be adjusted for changes of frequency. Drysdale’s Alternating poteniometer Continuous Current Potentiometer. This is accomplished by supplying it through a phase-shifting transformer which consists of a stator wound with ;otentiometer circuit, which produces a rotating field in a closely-fitting rotor. 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 usual manner.


The “balance” potenfiometer obtained by successive approximation of the usual adjustment of the potentiometer contacts dial and slide wire reading and of the phase-shifting transformer until the indicator shows no deflection.

Calibration of watt meter. In order to obtain a balance, as indicated by the detecting instrument, it must be possible to give to the potentiometer current any phase displacement relative to that of the potential supplying it. There is a provision on the scale that it could read phase angle up to Thus, the resultant voltage of the coordinate AC potentiometer is And the phase angle is given by.


Measures voltage as magnitude and phase from reference voltage. Now the in-phase component V A of the unknown e. 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.

Applications of AC Potentiometer Measurement of self-inductance. Coordinate type Potentiometer In coordinate AC potentiometertwo separate potentiometers are caged in one circuit as shown in the figure. Further, the phase relation between the circuit to be measured and that supplying the potentiometer may have any value from to Drysdale for the measurement of alternating potentials. The first one is named as the in-phase potentiometer which is used to measure the in-phase factor of an 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 pokar the winding. By doing some adjustments in sliding contacts and rheostat, the whole circuit gets balanced and galvanometer reads zero at the balanced condition. When current start flowing from stators, the rotating field is developed around the rotor and due to it e.

The potentiometer, which is the universal instrument by which currents are ppolar in terms of a difference of potential between the end of a known resistance, has been developed by C. Join our Mailing List by adding your email address below and be kept up to date potentometer lots of information including: Click on the Images For Detail.


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. Arrangements are provided for reversing the ammeter in order to eliminate the effect of stray fields. The phase displacement drysdwle the rotor pitentiometer is equal to rotor movement angle from its original position and it is related to the stator supply voltage.

AC Potentiometers

As the vibration galvanometer has also to be adjusted for such changes, it is necessary to have a source of a very steady frequency and voltage for satisfactory working.

Between the stators, there is laminated rotor having slots and winding which supplies voltage to the slide-wire circuit of the Potentiometer. Connects Facebook Youtube Videos. In a phase-shifting transformer, there is a combination of two ring-shaped laminated pltentiometer stators connected perpendicularly to each other as shown in the figure. The function of the series components is to maintain constant AC supply in the potentiometer by doing small adjustments in it.

Now to measure unknown e. These are adjusted until the A. The working phenomenon of DC potentiometer and AC potentiometer is same.

One is directly connected to power supply and the other one is connected in series with variable resistance and capacitor. We are extremely grateful for the very kind donation from Rosemary Helme of this Drysdale Alternating and Continuous Current Drysxale. The indicator for low frequencies is a vibration galvanometer which must be closely tuned to resonate to the frequency of the circuit. There are two types of AC potentiometers: Web Drysdalr by Pure Energy.

The reading of a sensitive dynamometer type ammeter in the main circuit is noted. Further references can be found at: Related pages What is Potentiometer?

The instrument comprises the standard Tinsley DC potentiometer of the time, with a phase shifter, Polwr dynamometer voltmeter, selection and change-over switches and terminal panels for connection of galvanometers, DC and AC measuring and supply voltages.

The potentiometer – is then thrown on to the A. The rotor has a winding on it which supplies the potentiometer current.