Attention should be paid to the measurement of current transformer

- Jul 27, 2020-

1. The primary winding of the current transformer is connected in series with the tested circuit, and the secondary winding is connected in series with the electrical measuring instrument. Pay attention to the polarity of the current transformer when wiring. When the lead wire of the internal coil of the current transformer is connected to the wrong position, the terminal button sign When it is wrong, it belongs to the reverse polarity of the coil. Only when the polarity is connected correctly, can we measure and measure accurately.

2.In order to prevent the high voltage from entering the low voltage side after the insulation breakdown between the primary and secondary windings, which endangers the safety of the person and the instrument, the secondary side of the current transformer should be provided with a protective ground point, and only one ground point is allowed to be connected. The box terminal close to the current transformer is grounded.

3.When the load variation range is large and the actual load current is less than 30%, the multi-variable ratio current transformer with taps in the secondary winding or 05s, 0.2s current transformer should be used, or the short-term thermal current with a higher rating A small-range current transformer with stable dynamic current and close to the actual load current.

4. The secondary winding of the current transformer is not allowed to open, otherwise, it will produce high voltage and endanger the safety of equipment and operating personnel. At the same time, due to the overheating of the iron core, there is a possibility of burning the transformer, and the error of the current transformer has also increased. .

5. The connecting wire of the secondary circuit should use copper single-core insulated wire, aluminum wire is strictly prohibited, and there must be no joints in the middle. The wire cross-sectional area of the current secondary circuit should not be less than 4mm^2.

6. The secondary circuit of the current transformer used for electrical measurement should not be connected to the relay protection device and automatic device to prevent mutual influence.