What is the disadvantages of current transformer?

Disadvantages are that it is high loss type of transformer due to the large air gap and not suitable for use as a power transformer. The open circuit secondary is VERY HIGH and dangerous. The secondary MUST be kept shorted out.

What is transformer exciting current?

Definition of exciting current 1 : a current that excites or energizes an electrical apparatus (such as the field magnets of a dynamo) 2 : the current taken by the primary of a transformer on no load.

Does exciting current vary with load?

The exciting current in the transformer remains fairly constant whether the transformer is at load or no load. The main purpose of the exciting current is to generate flux in the transformer.

What is the problem of current inrush in a transformer Why does it happen?

The inrush current phenomenon occurs due to temporary over fluxing of the transformer core. This may depend upon [6]: Switching instant on the voltage waveform at which the transformer is energised. The magnitude and polarity of the residual flux present in the transformer during re – energisation.

What are the advantages of current transformer?

Advantages of current transformer

• Measures high currents.
• High effective cores.
• High electrical isolation.
• Simple construction.
• Easy supply and control functions.
• Effective measurements.
• Clamp-on types.
• Easy maintenance and installation.

What are the advantages and disadvantages of instrument transformer?

Advantages & Disadvantages of Instrument Transformer

• These transformers use ammeter & voltmeter to measure high currents & voltages.
• By using these transformers, several protecting devices can be operated like relays otherwise pilot lights.
• Instrument transformer based transformers are less cost.

What is exciting current in induction motor?

Unlike that of a power transformer, the magnetic circuit of the induction motor has an air-gap. Therefore, the exciting current of induction motor (3O to 4O\% of full-load current) is much higher than that of the power transformer. Consequently, the exact equivalent circuit must be used for accurate results.

Why excitation current of transformer is non sinusoidal?

If the transformer iron core did not saturate, the magnetizing current (Im), generated by the flux, would be sinusoidal in shape and in phase with the flux. The result is that the magnetizing current is symmetrical, but cannot be sinusoidal due to the magnetization curve nonlinearity.

How do you measure exciting current?

the exciting current measurement is performed by applying an aC (60hz) Voltage (typically at 10kV) across a primary winding of the transformer while simultaneously measuring the current flowing through the same primary winding (while the secondary and ter- tiary winding(s) of the transformer are open-circuited).

What are the effects of inrush current?

In few cases the amount of current supplied to the circuit gets beyond the acceptable maximum voltage of the load circuit, causing permanent damage to the load. In high voltage AC motors, the high inrush current causes the power switch to trip or sometimes burned out.

Is inrush current bad?

The ratio of inrush current to normal full-load current can range from 5 to 100 times greater. This current surge can cause component damage and/or failure within the equipment itself, blown fuses, tripped circuit breakers, and may severely limit the number of devices connected to a common power source.