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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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.
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 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. 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.
S 1 and S 2 are signs changing switches which are used to change the polarity of the test voltage if it is required for balancing the Potentiometer.
As it is necessary to have the splitphase circuit somewhere near the resonating point, it must be adjusted for changes of frequency. Now the in-phase component V A of the unknown e.
Coordinate type Potentiometer In coordinate AC potentiometertwo separate potentiometers are caged in one circuit as shown in the figure. Arrangements are provided for reversing the ammeter in order to eliminate the effect of stray fields. Related pages What is Potentiometer? The known voltage may be supplied by a standard cell or any other known voltage-reference source.
The working current is standardized by reference to a known voltage source as a first step in the measurement. 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. 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 – Computing History
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 a.c.potenyiometer that they must be supplied from the same source. 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.
These children deserve a space which is engaging and instructive, where they can feel a sense of adventure, exploration and surprise! The function of the series components is to maintain constant AC supply in the potentiometer by doing small adjustments in it. Further, the phase relation between the circuit to be measured and that supplying the potentiometer may have any value from to For higher frequencies a telephone may be used. The “balance” is obtained by successive approximation of the usual adjustment of the potentiometer contacts dial and slide wire ppolar and of the phase-shifting transformer until the indicator shows no deflection.
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 a.d.potentiometer of galvanometers, DC and AC measuring and supply voltages. And when both of them are equal the galvanometer indicates the null point. The basic principle here is measuring an unknown voltage by comparing it with known voltage.
The switch is thrown to the calibrate position and the galvanometer key is tapped while the rheostat is adjusted for zero deflection on the galvanometer. 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. Connects Facebook Youtube Videos.
These instruments are provide with two scales to read respectively the inphase component V1 and the quadrature component V2 of the unknown voltage V. If the reading does not agree, a second measurement must be made, again returning to a calibration check after completion. Leave a Reply Cancel reply Your email address will not be published. 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.
This ammeter must read correctly with alternating and continuous currents.
The instrument is balanced by the main dial and the slide wire, leaving the protective resistance again in the circuit. Measures voltage as magnitude and phase from reference voltage. The operation of the AC potentiometer is quite complicated as compared to the DC potentiometer.
The known source may be DC or AC. There is a provision on the scale that it could read phase angle up to The slide wire type of potentiometer is not a practical form of construction. Thus, the resultant voltage of the coordinate AC potentiometer is And the phase angle is given by.
These are adjusted until the A.
Tag: polar type ac potentiometer
The first one is named as the in-phase potentiometer which is used to measure the in-phase factor of an unknown e. When current start flowing from stators, the rotating field is developed around the rotor and due to it e.
Click on the Images For Detail. The potentiometer – is then thrown on to the A.