What are the possible errors in energy meter?

What are the possible 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.

What 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 is the requirement for adjusting the speed of energy meters?

Lag Adjustment In Energy Meters The energy meter will register correct energy only if the shunt magnet flux lags the voltage exactly by 90°. This requires that the pressure coil should be highly inductive. If the angle is not 90°, it is to be adjusted by shading bands provided on the central limb of the shunt magnet.

How is speed error in energy meters eliminated?

Therefore, by changing the position of the braking magnet the speed of the rotating disc can be controlled. If the meter runs fast, the braking magnet will be moved away from the center of the disc, which increases the radius, which in turn decreases the speed of the disc.

Which one below is error in energy meter *?

2. Phase angles in an energy meter cannot be incorrect. Explanation: In an energy meter, phase angle errors occur as a result of improper adjustments of lag condition, abnormal frequencies etc. Due to temperature, changes in resistance values also lead to error in the phase angle.

Which energy meter system contains a rotating aluminium disc that is placed between the air gaps of series and shunt magnets and mounted on a shaft?

It is also known as kilowatt-hour meter or Induction type watt-hour meter. It is a type of ”integrating instruments. ”

Which of the following controls speed of an energy meters?

In this system a thin aluminum disk placed in the air gap between the two electromagnets and mounted on a vertical shaft which is free to rotate. This system has a permanent magnet called brake magnet. It is located near the disk so that eddy currents are induced and braking toque to the disk and control the speed.

Why testing of energy meter is required?

To this end, it is important to test the quality and reliability of energy meters in order to ensure accuracy in the recording of electricity consumption and billing. Meter testing further prevents meter malfunctioning and failures and ensures long life of meters without any degradation in performance.

Which error is caused by braking system of energy meter?

Speed Error : These eddy currents when interacts with the magnetic field produced by the braking magnetic produce a braking torque on the disc.

Why is the rotating disc made of aluminium and is thin?

The rotation of metallic disk is operated by two coils. Both the coils are arranged in such way that one coil produces a magnetic field in proportion to voltage and the other coil creates a magnetic field proportion to current. As a result of it, a lite weight aluminum disk rotates in an air gap.

What is the material of the disc of energy meter and why this used?

The components of this system are two silicon steel laminated electromagnet. Upper magnet→ Shunt magnet→ behave as potential coil.

What is the working principle of energy meter?

The energy meter has the aluminium disc whose rotation determines the power consumption of the load. The disc is placed between the air gap of the series and shunt electromagnet. The shunt magnet has the pressure coil, and the series magnet has the current coil.

What is the relationship between the rotations of a disc and kWh?

Their rotation is directly proportional to the energy consumed by the loads in the kilowatt hour. The rotation of the disc is transmitted to the pointers of the different dial for recording the different readings. The reading in kWh is obtained by multiply the number of rotations of the disc with the meter constant.

Why is the full load speed of disc kept low?

In order to avoid the production of this self breaking torque, the full load speed of disc is kept as low as possible so that self breaking torque can be reduced. Errors in single phase energy meters: The errors caused by both the system (i.e. driving and braking) are separating written as follows:

Why does a disc start rotating when the voltage is low?

The field induces by the voltage coil is lagging by 90º on the magnetic field of the current coil because of which eddy current induced in the disc. The interaction of the eddy current and the magnetic field causes torque, which exerts a force on the disc. Thus, the disc starts rotating.