Precautions and detection in the operation of current transformers - Database & Sql Blog Articles

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1. Detection of current transformer

The current transformer acts as a current transformer and electrical isolation. It is convenient for the secondary instrument measurement to be converted into a relatively uniform current, avoiding the danger of directly measuring the current transformer circuit. There are methods for detecting current transformers.

Transformer comprehensive tester: Measure the error between the standard transformer and the test transformer, and display the working current.

Standard current transformer: used as a standard in the transformer test, the accuracy is generally two levels higher than the measured height, and the design has multiple ratio taps to adapt to the verification of different transformers.

Regulator: used to adjust the test current, generally installed in a console with protection and switch, and coarsely adjust and fine tune two regulators to meet the adjustment fineness. When measuring at rated current below 2500A, it can be made with a 10KVA universal regulator. The larger current must be specially made, generally requiring 30~60KVA.

Current riser: Matches with the regulator to match the various required test currents. Its capacity and cost increase with increasing current.

High-current connection cable: connect hundreds of meters, several thousand amperes of current, cable prices can not be ignored.

Load box: simulates the actual working state of the measured transformer.

2. Precautions in the operation of current transformer

In the line of power supply and electricity, the current and voltage vary widely from small to tens of thousands of amps. In order to facilitate the measurement of the secondary instrument, it is necessary to convert to a relatively uniform current, and the voltage on the line is relatively high as direct measurement is very dangerous. The current transformer acts as a transformer and electrical isolation. The precautions in the operation of the current transformer are:

The current transformer shall not open the circuit on the secondary side during operation. Once the secondary side is open, the iron loss is too large, the temperature is too high to burn, or the secondary winding voltage is increased to break the insulation, and there is a danger of high voltage electric shock. Therefore, when changing the meter, such as changing the ammeter, the active meter, the reactive meter, etc., the current loop should be shorted before the meter is exchanged. When the meter is adjusted, first connect it to the secondary circuit and then remove the short wiring and check whether the meter is normal. If sparks are found when the short wires are removed, the current transformers are open, and should be short-circuited immediately to find out that there is no open circuit in the meter circuit before the short wires can be removed. When removing the current transformer short-circuit work, it should be placed on the insulation pad. In addition, the protection device of the current transformer circuit should be deactivated. After the work is completed, the protection device can be put into operation.

When the insulation resistance of the secondary side coil of the current transformer is lower than 10~20 megohms, it must be dried to restore the insulation before use.

At one end of the secondary side of the current transformer, the outer casing must be reliably grounded.

If the current transformer is humming, check the inner core for looseness and tighten the core bolt.