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. An electrodynamic type instrument consists of Two Fixed Coil, flux is used in Electrodynamic or Electrodynamometer type instrument. This means that the torque in electrodynamometer instruments must have . Electrodynamometer type voltmeters are the most accurate type of.

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And the value of current is given by the equation. In metal parts of the instrument the eddy current gets produced. The average deflection torque of the coil is given as. Hnec metal parts should be kept as minimum as possible. This is great one to see your blog last time I see same design to my friend constraction building in chennai. This mechanical force deflects the pointer which is mounted on the calibrated scale.

Electrodynamometer type Instruments – Construction and Operation

In electrodynamometer instrumentsthe field can be made of reverse simultaneously with the current in the movable coil if the field fixed coil is connected in series with the movable coil. The instrument consists of a fixed coil and a moving coil.


Therefore energy input to the instrument. Also the resistivity of the metal parts used must be high, to elecyrodynamometer the eddy currents. The temperature errors are caused due to the self heating of the coil, which causes change in the resistance of the coil.

Errors may be due connections. Newer Post Older Post Home. This means that as the direction of magnetic field changes, the direction of current in moving coil also changes.

Electrodynamometer Instruments are widely used as an ammeter, voltmeter and wattmeter. Thus the deflection is proportional to the product of the two currents and the rate of change of mutual inductance.

The magnetic filed in electrodynamic type instrument is very week of the order of 0. Please keep doing this. Therefore it becomes very important to protect the instrument from the effect of external magnetic field.

Errors in the pressure coil inductance. Torque to weight ratio: The average torque for one time period of the currents are given by.

Electrodynamometer Type Instruments ~ your electrical home

Construction and Working Principle of Electrodynamometer Electridynamometer Wattmeter Now let us look at constructional details of electrodynamometer. Thus temperature compensating resistors can be used in the precise instrument to eliminate the temperature errors.


Sometimes a suspension may be used, in case a high accuracy is desired. Grab it now for very less price.

Torque Equation in Electrodynamometer Instruments | Electrical Concepts

So the expression for the torque can be written as: The torque acts on the coils becomes. Let I 1 and I 2 be the current in fixed and moving coil respectively.

Let the currents passing through fixed and moving coils be I 1 and I 2 respectively. Advantages of Electrodynamometer Type Wattmeter Following are the advantages of electrodynamometer type wattmeter and they are written as follows: Related pages Measurement of Three Phase Power.

Moving coil is serves the purpose of converting the actuating quantity into readable value on the scale. Leave a Reply Cancel reply Your email address will not be published. From the above two cases, we can have following conclusions: These springs act as leads to the inwtruments coil.