How many tests are there in current transformer?

What tests are done on a transformer?

Five electrical transformers tests to conduct before installation

  • Megger Test. This test is also known as Insulation resistance test and is done to gauge the quality of insulation within the transformer. …
  • Oil Test. …
  • Turns Ratio Test. …
  • Resistance Test. …
  • Polarity Test.

What is a CT burden test?

The CT burden is the amount of impedance (AC Resistance) connected to the CT secondaries and is usually rated in ohms or volts. The manufacturer only guarantees CT accuracy up to a maximum burden rating and CT performance will degrade if the secondary burden is larger than rated.

What is TTR test of transformer?

Transformer Turns Ratio (TTR) testing is one of the most common ways of assessing the condition of a transformer’s windings and core. Throughout the life of a transformer, TTR results are compared against the nameplate ratings to reveal insulation deterioration, shorted turns, core heating or other abnormalities.

What is the CT ratio?

Ratio. 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.

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How is CT ratio calculated?

Calculate the CT ratio. The CT ratio is the inverse of the voltage ratio. In this example, the voltage ratio is 1:5, so the CT ratio is 5:1. This means the current level is stepped down 5 times where, if the primary current is 200 amps, the CT output is 40 amps.

What is current transformer meter?

CT (Current Transformer) Meters are installed on any connections with a load greater than 100 Amps. A CT meter only measures a fraction of the current passing through the connection and a multiplier is applied to this reading to reflect the actual current. …

What is bushing CT?

A transformer bushing CT (BCT) is a window-type current transformer mounted around the bushing’s flange. They may be inside the main tank (under the cover) or mounted externally. A bushing type CT consists only of a toroidal-shaped core with a secondary winding.

What is measuring current transformer?

A measuring current transformer is used to reduce currents in a circuit to a level that can safely be measured by a metering device. … All SADTEM outdoor transformers are designed to operate without the need for maintenance.

What is CT polarity?

The Polarity marks on a CT designate, the relative instantaneous directions of the current I.e for a given direction of Primary current (entering), what should be the direction of the secondary current (leaving).