How To Use Current Transformers

Current transformers are usually installed in high-voltage transmission lines or equipment such as large motors. They convert high current into low current through the principle of electromagnetic induction, and then output it to the detection circuit for use. The following are detailed steps and precautions for using current transformers:

1、 Understand the basic parameters of current transformers

Rated current: A current transformer has a rated current value that represents the maximum current it is designed to measure.

Accuracy: Accuracy is an indicator of the measurement accuracy of current transformers. Choosing an appropriate accuracy can improve measurement accuracy and reduce errors.

Polarity: Current transformers have clear polarity, namely input and output terminals. The correct polarity connection is crucial for ensuring the accuracy of measurements.

2、 Wiring method

Single phase current transformer:

Connect the input terminal (usually P1) of the current transformer to the positive terminal of the circuit under test, and connect the output terminal (usually P2) to the input terminal of the measuring device.

Ensure that the secondary side (i.e. output terminal) of the current transformer is short circuited or connected to an appropriate load to prevent open circuits from generating high voltage.

Three phase current transformer:

For three-phase circuits, each phase requires a current transformer.

According to the wiring method of single-phase current transformers, connect the input terminal of each current transformer to the corresponding phase line, and connect the output terminal to the input terminal of the measuring equipment.

3、 Installation precautions

Location selection: The current transformer should be installed in an appropriate position on the tested circuit to ensure measurement accuracy. Usually, it should be installed at the input or output of the circuit in order to measure the current of the entire circuit.

Fixed method: The current transformer should be firmly fixed in the installation position to prevent measurement errors caused by vibration or movement.

Secure wiring: When wiring, ensure that the input and output terminals of the current transformer are firmly and reliably connected to the circuit and measuring equipment to prevent measurement errors caused by poor contact.

4、 Usage and maintenance

Regular inspection: Regularly check whether the wiring of the current transformer is loose or damaged to ensure that it is in good working condition.

Cleaning and maintenance: Regularly clean the dust and dirt on the surface of the current transformer to maintain its good heat dissipation performance and measurement accuracy.

Avoid overload: Avoid operating the current transformer for a long time beyond its rated current to prevent overheating or damage.

5、 Safety precautions

Power off operation: When wiring, installing or maintaining the current transformer, the power supply of the circuit should be disconnected first to ensure the safety of the operation.

Protective measures: When operating current transformers, appropriate protective equipment such as insulated gloves and shoes should be worn to prevent electric shock accidents.

In summary, the correct use of current transformers is crucial for the safety and normal operation of power systems. During use, the above steps and precautions should be strictly followed to ensure measurement accuracy and equipment safety.