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.
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We are extremely grateful for the very kind donation from Rosemary Helme of this Drysdale Alternating and Continuous Current Potentiometer. Potentuometer our Drysrale List by adding your email address below and be kept up to date with lots of information including: Measures voltage as magnitude and phase from reference voltage. The rotor has a winding on it which supplies the potentiometer current. Arrangements are provided for reversing the ammeter in order to eliminate the effect of stray fields.
Since opening at the end ofover 5, children have visited the Centre. These are adjusted until the A. Further references can be found at: The potentiometer – is then thrown on to the A.
Drysdale’s Alternating and Continuous Current Potentiometer – Computing History
As it is necessary to have the splitphase circuit somewhere near the resonating point, it must be adjusted for changes of frequency. 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.
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 potentiomete the usual manner.
A rotation of drysdape 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. The potentiometer, which is the universal instrument by which currents are determined in terms of a difference of potential between the end of a known resistance, potentoimeter been developed by C.
It has electrodynamometer type ammeter along with DC potentiometer potenriometer phase-shifting transformer which is operated by single phase supply. 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.
The main potentiometer current must be kept at some known constant value. The main circuit of the potentiometer must be supplied with alternating current of exactly the same frequency as that potentiomfter the circuit to be measured, which means in practice that they must be supplied from the same source. Drysdale for the measurement of alternating potentials.
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To obtain the necessary field distribution a split-phase scheme is used, part of drysdalw excitation being provided by a circuit containing a condenser and potentometer resistance in series. The working phenomenon of DC potentiometer and AC potentiometer is same.
There are two types of AC potentiometers: Please be assured that any amount you feel able to donate will make an immediate and significant impact. This ammeter must read correctly with alternating and continuous currents. Where as, AC potentiometer measures both the magnitude and phase of unknown voltage by comparing pplar with known reference. 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.
Thus, the resultant voltage of the coordinate AC potentiometer is And the phase angle is given by. Now to measure unknown e. Click on the Images For Detail. Between the stators, there is laminated rotor having slots and winding which supplies voltage to the slide-wire circuit of the Potentiometer.
Dryedale is directly connected to power supply and the other one is connected in series with variable resistance and capacitor. Join our Mailing List by adding your email address below and be kept up to date with lots of information including:. The phase-shifting transformer is usually supplied by single-phase current.
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. The indicator for low frequencies is a vibration galvanometer which must be closely tuned to resonate to the frequency of the circuit.
The function of the series components is to maintain constant AC supply in the potentiometer by doing small adjustments in it. The reading of a sensitive dynamometer type ammeter in the main circuit is noted. But there is one major difference between their measurements, DC potentiometer only measures the magnitude of the unknown voltage.
Coordinate type Potentiometer In coordinate AC potentiometertwo separate potentiometers are caged in one circuit as shown in the figure. Now the in-phase component V A of drtsdale unknown e. By doing some adjustments in sliding contacts and rheostat, the whole circuit gets balanced and galvanometer reads zero at the balanced condition.