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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Measures voltage as magnitude and phase from reference voltage. 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. Between the stators, there is laminated rotor having slots and winding which supplies voltage to the slide-wire circuit of the Potentiometer.
It has electrodynamometer type ammeter along with DC potentiometer and phase-shifting transformer which is operated by single phase supply. The function of the series components is to 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.
One is directly connected to power supply and the other one is connected in series with variable resistance and capacitor. 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. But there is one major difference between their measurements, DC potentiometer only measures the magnitude of the unknown voltage. Join our Mailing List by adding your email address below and be kept up to date with lots of information including: There are two types of AC potentiometers: Related pages What is Potentiometer?
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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 known source may be DC or AC. 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 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. Click on the Images For Detail. The potentiometer – is then thrown on to the A.
Further, the phase relation between the circuit to be measured and that supplying the potentiometer may have any value from to 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, potentiomeeter and change-over switches and terminal panels for connection of galvanometers, DC and AC measuring and supply voltages.
Now to measure unknown e.
Drysdale ac polar potentiometer
The rotor has a winding on it which supplies the potentiometer current. Coordinate type Potentiometer In coordinate AC potentiometertwo separate potentiometers are caged in one circuit as shown in the figure.
The indicator for low frequencies is a potentioeter galvanometer which must be closely tuned to resonate to the frequency of the 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. By doing some adjustments in sliding contacts and rheostat, the whole circuit gets balanced and galvanometer reads zero at the balanced condition. The reading of a sensitive dynamometer type ammeter in the main circuit is noted.
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 first one is named as the in-phase potentiometer which is used to measure the in-phase factor of an unknown e.
Drysdale’s Alternating and Continuous Current Potentiometer – Computing History
To obtain the necessary field ppotentiometer a split-phase scheme is used, part of the excitation being provided by a circuit containing a condenser and a resistance in series. Applications of AC Potentiometer Measurement of self-inductance.
Further references can be found at: Now the in-phase component V A of the unknown e. These are adjusted until the A.