How To Repair Differential Current Transformers?

In this article, we will uncover some possible causes that might cause current transformer troubleshooting, and then I will share some possible solutions that you can try to solve this problem.

There must be no interrupting circuit on the secondary side of the main line of the working current transformer. As soon as the circuit is open at all volts On the other hand, high temperature causing excessive iron losses can burn out the current transformer or increase the total voltage of the secondary winding, which will break the insulation and create a risk of high voltage electric shock. Therefore, when replacing a meter such as an ammeter, true potential meter, and reactive power meter, make sure the circuit is severely shorted before use. After replacement, put the meter in the secondary state, then short out the electrical wires, checking if the meter is really good. If sparking occurs after the short circuit wires controlling the CT trip are removed, reclose the loop and check that the meter loop is not currently an open circuit. When removing short-circuit wires between a current transformer, stand on an insulated surface and consider the last protection to stop the last circuit of the transformer. When the job is done, you can attach special protection for dfor use.

If the current transformer makes a pleasant sound, check if the inner core is loose, usually fix the core with bolts.

How do you troubleshoot an electrical transformer?

Identify the transformer terminals by the designer’s sticker.Switch the multimeter to its VAC function.Test most of the transformer input voltage with a multimeter, using the transformer label as an accurate connection guide.Check the transformer output voltage with a multimeter.

The second side of the current transformer housing must be reliably grounded.

troubleshooting current transformers

If the total resistance of the current transformer secondary is less than 10~20MΩ, the insulation must be restored by drying before reuse.


If the current transformer has high standard errors, it will affect the operation of the primary process circuits. Please immediately notify the higher authorities and officials of the relevant departments of the monthly outage of the differential current transformer, and then deal with it. For some breaks in the secondary winding, treatment should be carried out according to actual diseases. After taking the necessary safety measures in accordance with the applicable regulations, the current transformer can be fully used again.

troubleshooting current transformers

Current transformers play a key role in monitoring and protecting electrical power systems. TT is a measurePower transformers used to convert peak current into reduced secondary current for use in meters, relays, power devices and other appliances.

Testing instrument transformers is often taken too lightly. Instrument current transformers have a high level of accuracy to ensure accurate metering, while any equipment used for protection must respond very quickly and correctly in the event of a fault.

Risks such as swapped measurement and protection system transformers and swapped connections can be greatly reduced by testing before first use. At the same time, electrical fluctuations in the current transformer, caused, for example, by the aging of the insulation, can be detected at an early stage. This is

For a number of reasons, it is important that current transformers, and thus the instruments connected to them, can be checked and calibrated regularly. There are 6 electrical tests that should normally be performed on current transformers to ensure Accuracy and optimum reliability of the software:

1 Name=”ratio”>. Ratio

The CT ratio is usually described as the ratio of the input current to the secondary source current at full load. For example: A CT with a ratio of 300:5 produces 5 A of another current when 300 A passes through the primary winding.

How do you check CT burden?

Load for TC measurement type = Total load of measuring devices (digital/analogue ammeter, voltmeter, wattmeter, MCM, transducer) installed in series with TC + Total VA power of TC fittings cable and measuring devices. Cable VA = (2L x R x I^2).

As the primary current changes, so does the secondary output current. For example, if 150 integrated amplifiers are driven through a primary rating of 300 A, the secondary output current rating is likely to be 2.5 A.

Unlike a voltage transformer, a current transformer consists of one or more turns of the primary winding. Each of these primary windings may consist of a single flat turn, a strong wire nailer wrapped tightly around the core, or simply a special conductor or bar passed through a full center hole.

A ratio check is performed to confirm that the ratio is within the specified range.Check the Is ct setpoint to ensure that the ratio is correct for different tapped CT taps. The turns ratio corresponds to the voltage ratio related to voltage transformers and can be specified as follows:

The ratio test is done by: applying an appropriate voltage (undersaturation) to actually determine the secondary voltage of the CT under test, and measuring the primary segment voltage to calculate the ratio portion of the above term ci.< / p >

DANGER: Be careful when performing a current transformer ratio test and DO NOT run a voltage high enough to saturate the transformer. Applying saturation causes the reading to show only voltage, which is inaccurate.

2. Polarity Check

The polarity of an individual CT is determined by the path in which the windings are cut around the transformer core (clockwise or anti-clockwise)clockwise) and how the qualified leads are extracted from the CT case. All current transformers are subtractive polarized and must have the following markings to visually identify current flow:

How do you test a current transformer?

The winding resistance of a current transformer is found by dividing the voltage drop across the winding (measured with a DC millivoltmeter) by the applied DC current constantly flowing through the winding. The current transformer should be demagnetized after the winding resistance test is completed.

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Felsökning Av Strömtransformatorer
변류기 문제 해결
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Поиск и устранение неисправностей трансформаторов тока
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