What is CT excitation test?
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 are the different testing methods used in transformer?
Four Methods for Testing Transformers
- Turns Ratio Testing. Turns ratio transformer testing is commonly used to ensure that the winding ratio between the primary and secondary coils are aligned to recommended specifications.
- Insulation Resistance Testing.
- Power Factor Testing.
- Resistance Testing.
How do you test insulation resistance in CT?
Insulation Resistance Test
- Use Megger mit1020 to measure insulation resistance.
- Insulation Resistance Tests to be done: Primary winding – Ground (Apply 5000V for 1 minute) Primary winding – Secondary winding (Apply 2500V for 1 minute) Secondary winding – Secondary winding (Apply 2500V for 1 minute)
What is CT ratio test?
Turns ratio Tests (optional test) This test is to ensure the turn’s ratio of CT at all taps. The primary current of minimum of 25% rated primary current to be injected on primary side of CT with secondaries shorted and the secondary current can be measured and recorded for all cores.
What is a Doble test in transformer?
Fundamentally, the tests are used to assess the AC characteristic of the dielectric; one such value is dielectric losses, the real component of the current, which relates to contamination and/ or deterioration of dielectric.
How does CT analyzer work?
CT analyzer is a necessary instrument of on-site verification accuracy of current transformer. The CT analyzer designed and developed in this paper use the new method of indirect test – low pressure method, which gets current transformer contrast and angle difference by measuring the internal parameters of the CT.
What are CT ratios?
The CT ratio is the ratio of primary current input to secondary current output at full load. For example, a CT with a ratio of 300:5 is rated for 300 primary amps at full load and will produce 5 amps of secondary current when 300 amps flow through the primary.
What is an exciting or excitation current?
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 excitation voltage and 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 saturation?
CT saturation is a term used to describe the state wherein. a CT is no longer able to reproduce an output current in. propotional to its primary current or as per its Ratio. The basic reason for CT saturation is due to the property. of the core which goes to magnetic sturation due to number.
