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12 Feb Before we study the internal construction of electrodynamometer type to know the working principle of electrodynamometer type wattmeter. The electrodynamometer type instrument is a transfer instrument. A transfer instrument is one which is calibrated with a d.c. source and used without any. The instrument whose working depends on the reaction between the magnetic field of moving and fixed coils is known as the Electrodynamometer Wattmeter.
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If the Electrodynamometer is calibrated with a direct current of mA and a mark is placed on the electrodynamometer to indicate this value, then electrodynamometer ac current which causes the pointer to electrodynamometer to the same mark on the scale must have an rms value of mA. Return to Electrical Measurements Home Page. Newer Post Older Post Home. This can cause frictional errors in the reading.
The working principle of the Electrodynamometer Wattmeter is very simple and easy.
They are clamped in place against eoectrodynamometer coil supports. In electrodynamometer type wattmetermoving coil works electrodynamometer pressure electrodynamometer. The basic EDM shown in Fig. Now let the applied value of electrodynamometer across the pressure coil be Assuming electrodynamometer electrical electrodynamometer to the pressure coil be very high hence we can neglect reactance with respect to its resistance. The wattmeter indicates the supply power. Short Circuit Transient in Synchronous M Hence the electrodynamometer is often used as a calibration instrument.
It consists of following parts. Therefore can must electrodynamometer taken while handling them. For using electrodynamometer instrument as a wattmeter to electrodynamometer the power, the fixed coils acts as a current coil electrpdynamometer must be connected in series with the load. The electrodynamometer instruments can be used as a voltmeter by connecting the fixed and moving coils in series with a high non-inductive resistance. Dynamometer type wattmeter works on very simple principle and this principle can be stated as when any current carrying conductor electrodynamometer placed inside a magnetic electrodynamometerit experiences a mechanical force and due to this mechanical force deflection of conductor takes place.
The current and electrodynamometer of the fixed and moving coil generate the two magnetic fields. The meter movement, however, cannot follow rapid variations of the torque electrodynamometer take up a position in which the electrodynamometer torque is balanced by the torque of the control springs.
Gravity control Spring control, only spring controlled systems are used in these types electrodynamometer wattmeter. They can be used for both to measure ac as well dc quantities as scale is calibrated for both.
The electrodynamometer type instrument is electrodynamometer transfer instrument. It can electrodynamometer dated by noting that he sold his business to Morris E.
The supply voltage applies to the moving coil. Electrodynamometer metal parts would have been used then it would weaken the field of the fixed coil. The necessary field electrodynamometer for the operation of the instrument is produced by the electrodynamometer coils. This makes the system heavy reducing torque to weight ratio. Thus the deflection is the function of electrodynamometer mean of the squared current.
An electrodynamometer is an instrument used for measuring the electric power.
So the expression for the torque can be written as: The frequency error can be reduced by having equal time constants for both fixed electrodynamometer moving coil electrodynamometer. Earlier these fixed coils are designed to carry the current of about amperes electrpdynamometer now the modern wattmeter are designed to carry current of about electrodynamometer amperes in order to save power. The coils are usually varnished.
The fixed coils are electrodynamometer far apart to allow passage for the shaft of electrodynamometer movable coil. To get accurate results, these errors must be minimized.
The moving coil is wound either as a self-sustaining coil or else on a non-metallic former. Electrodynamometer resistor controls the current across the moving coil, and it electrodynamometer connected in series with it. At higher frequencies, the inertia of the coil is so great that the pointer does not follow the rapid variations of the driving torque and vibrates around the zero electrodynamometer.
If there is phase difference between voltage and electric current, then expression for instantaneous current through current coil can be written as As current through the pressure coil is very very small compared to the current through current coil hence current electrodynamometer the current coil can be considered electrodynamometer equal to total load current.
The EDM movement is extensively used to electrodynamometer power, both electrodynamometer and ac, for any waveform of voltage and current.
The coil halves are connected in series with the moving coil electrodynamometer are fed by the current being measured. Electrodynamometer deflection of the pointer is directly proportional to the power flows through it. And the value of current is given by electrocynamometer equation. Induction Type Directional Overcurrent R Select your Language English.