Table of Contents
- 1 What is the value of magnetizing current in a transformer?
- 2 What is the value of magnetising current?
- 3 What is magnetising current in CT?
- 4 Why do we test magnetizing current in transformer?
- 5 What is excitation current?
- 6 What factors does the value of magnetizing current depend on?
- 7 What is excitation voltage?
- 8 What is CT excitation test?
What is the value of magnetizing current in a transformer?
Magnetization current can be defined as “the portion of the no-load current that is used to establish flux in the core of a transformer“. It is generally denoted by the letter Im. Generally, when a transformer is energized under no-load conditions, it draws a small amount of current.
What is the value of magnetising current?
1 Answer. Magnetising current will be practically irrelevant in a good mains transformer design. As it’s in quadrature to the load current, a mag current of 10% of the full load will increase the full load current of the transformer by 1% (Pythagorus). 10% is a very conservative estimate, it will typically be smaller.
What is the excitation current of the transformer?
A transformer exciting current is the current or amperes required to energize the core. Even with zero load, a transformer will draw a small amount of current due to internal loss. The excitation current is made up of two components.
What is magnetising current in CT?
The magnetizing impedance of the ct can be obtained by dividing each value of voltage read from the curve by the corresponding excitation current. The magnetizing impedance is non-linear, increasing from 3000 ohms at 0.001 amps excitation current to a maximum of 8000 ohms at 0.0248 amperes of excitation.
Why do we test magnetizing current in transformer?
Magnetizing Current test on transformer is performed to locate defects in the magnetic core structure, shifting of windings, failure in between turn insulation or problem in tap changers.
What is the use of auto transformer?
The autotransformer has many uses and applications including the starting of induction motors, used to regulate the voltage of transmission lines, and can be used to transform voltages when the primary to secondary ratio is close to unity.
What is excitation current?
Excitation current is the current flowing into the high voltage winding with the low voltage side open. This current should be proportional to the No-load acceptance test but with the difference resultant from the use of test voltages different from nominal values.
What factors does the value of magnetizing current depend on?
Explanation: There are 3 factors upon which the magnetizing current depends upon. They are total mmf required, number of turns in the exciting winding and upon the way in which the winding is distributed.
What is meant by excitation current?
What is excitation voltage?
An excitation voltage or current is the amount of electric energy ( D.C ) feed into the field winding of an alternator rotor to produce magnetic flux / field. The output voltage of an alternator depends upon the magnetic field and so the excitation voltage.
What is CT excitation test?
Excitation tests are performed by applying an AC voltage to the secondary winding of the CT and increasing the voltage in steps until the CT is in saturation. The “Knee” point is determined by observing a small voltage increase causing a large increase in current.
What is CT burden?
The burden of the CT is the resistive load used to create the voltage on the output. It varies with turns ratio, desired output and current rating of the primary.