# Why the concept of control torque is not employed in power factor meter?

## Why the concept of control torque is not employed in power factor meter?

The coil windings are so arranged that the torques due to the two coils are opposite in direction. So, there is no controlling torque.

Does power factor meter has any controlling torque?

Though power factor meter is an indicating instrument but no controlling torque is provided in this instrument. The currents are being led into the moving coils A and B by fine ligaments which exert no control.

What is the purpose of a power factor meter?

Definition: The power factor meter measures the power factor of a transmission system. The power factor is the cosine of the angle between the voltage and current. The power factor meter determines the types of load using on the line, and it also calculates the losses occur on it.

### What is the number of control springs used in a power factor meter?

The dynamometer power factor meter has two coils – a current coil and a pressure coil. The current coil has two fixed coils F1 and F2.

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What are the errors in energy meter?

The causes for error-wiring of three-phase three-wire electric energy metering device may include: the connection error between transformer and electric energy meter, the error of current transformer polarity and the error of voltage transformer polarity.

How the creeping error is controlled in energy meter?

Creeping can be prevented by providing two holes on the disc exactly opposite to each other. Whenever the hole comes under the shunt magnet, the disc stops rotating. Whenever the hole comes under the shunt magnet pole, the effective center of the eddy current change hence the eddy current get distorted.

#### When measuring power factor which meter should be connected to the circuit?

All Answers (6) Power factor in a single-phase circuit can be measured with the wattmeter-ammeter-voltmeter method, where the power in watts is divided by the product of measured voltage and current. You can measure the phase-shift between voltage and current by means of an oscilloscope or analyzer.

What are the advantages and disadvantages of single phase power factor meter?

No moving iron. High torque is to weight ratio. The moving element has no electrical contact with the circuit. Less affected by stray magnetic field.

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How many coils are there in power factor meter?

two coils
General construction of any power factor meter circuit include two coils namely pressure coil and current coil. Pressure coil is connected across the circuit while current coil is connected such that it can carry circuit current or a definite fraction of current.

## Is not important part of electronic energy meters?

Explanation: An electronic energy meter does not have frictional losses, creeping is not needed irrespective of the nature of the load such as low load, full load power factor, etc and the accuracy in the reading is of the order of ±1\%. 8.

Which is the cause of the speed error in the induction type energy meter?

Incorrect position of brake magnets. Incorrect adjustmentof the position of shading bands. Slow but continuous rotation of aluminum disc.

What are the errors found in induction type instruments?

(b) Temperature error (a) Frequency error Since deflecting torque depends on frequency, hence unless the alternating current to be measured has the same frequency with which the instrument was calibrated, there will be large error in its readings.

### What is the working principle of power factor meter?

The basic working principle of power factor meter is similar to that of dynamometer type wattmeter i.e. when the field produced by moving system tries to come in line with the field produced by the fixed coil, deflecting torque is exerted on the moving system which deflects the pointer attached to it (the moving system).

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Can torque be controlled in power factor meter?

Though power factor meter is an indicating instrument but no controlling torque is provided in this instrument. The currents are being led into the moving coils A and B by fine ligaments which exert no control.

What are the advantages and disadvantages of electrodynamic type power factor meters?

Losses are less because of minimum use of iron parts and also give less error over a small range of frequency as compared to moving iron type instruments. They high torque is to weight ratio. Disadvantages of Electrodynamic Type Power Factor Meters Working forces are small as compared to moving iron type instruments.

#### How does frequency and waveform affect the deflection in power factor meters?

The deflections in three phase power factor meters are independent of frequency and waveform since the currents in the two moving coils are affected in the same way by any change of frequency. Power factor meter connection is shown in Figure.