What is the principle of transformer demagnetization device?

The principle of demagnetization instrument is mainly based on the basic principles of electromagnetics, which eliminates residual magnetism in the target object by generating a specific form of magnetic field. The following is a detailed explanation of the principle of the demagnetizer:

1. Basic principles

① Magnetic field interaction:

The demagnetizer interacts with the residual magnetism in the target object by generating an alternating magnetic field or a direct current magnetic field inside it. This interaction will change the direction of the magnetic moment in the target object, gradually reducing or eliminating the remanence.

② Hysteresis loop reduction:

During the demagnetization process, the demagnetizer will bring the target object closer to the magnetic field it generates, causing the magnetic moment inside the target object to reach saturation. Then, gradually remove the target object from the magnetic field, and the hysteresis loop will gradually shrink until the residual magnetism is completely eliminated.

2. Specific implementation method

① Communication method:

In the communication method, the demagnetizer generates an alternating magnetic field in the electromagnetic coil by passing an alternating current through it. This alternating magnetic field will interact with the residual magnetism in the target object, gradually eliminating the residual magnetism by changing the direction of the magnetic field multiple times. For example, in demagnetization of power transformers, a 50Hz AC voltage can be applied to the low voltage side of the transformer and gradually increased to the rated voltage to achieve demagnetization.

② DC method:

The direct current law is to apply direct current in both directions in a demagnetizer and gradually reduce the current value to reduce the hysteresis loop of the iron core, thereby achieving the goal of eliminating residual magnetism. For example, in demagnetization of transformers, direct current can be applied in both directions to the high-voltage winding of the transformer, gradually reducing the current value until residual magnetism is eliminated.

3. Demagnetization process

① Preparation stage:

Connect the demagnetizer to the target object and ensure that the circuit connection is correct and error free. Meanwhile, select the appropriate demagnetization mode and parameters based on the type and remanence of the target object.

② Demagnetization operation:

Start the demagnetizer to generate a magnetic field. In communication methods, demagnetizers generate alternating magnetic fields; In the direct current method, a direct current will be applied. Place the target object in a magnetic field and perform necessary operations according to the instructions of the demagnetizer.

③ Monitoring and recording:

During the demagnetization process, the magnetic field strength and demagnetization effect can be monitored through the built-in monitor of the demagnetization instrument or an external testing instrument. At the same time, record the key parameters and data during the demagnetization process for subsequent analysis and evaluation.

④ End stage:

When the demagnetizer indicates demagnetization completion, turn off the demagnetizer power and disconnect it from the target object. At this point, the residual magnetism in the target object has been eliminated or reduced to an acceptable range.

4. Precautions

① Safe grounding:

Before using the demagnetizer, it is essential to ensure that the ground wire is firmly grounded to ensure safety.

② Electrical verification operation:

Before demagnetizing high-voltage equipment such as transformers, it is necessary to perform electrical testing to confirm that there is no electricity before the operators can carry out wiring and demagnetization operations.

③ Protective measures:

When performing demagnetization operations, safety precautions should be taken to prevent safety accidents such as electric shock and falling from heights.

④ Control time:

The continuous use time of the demagnetizer should not be too long to avoid damaging the equipment or affecting the demagnetization effect. The usage time should be reasonably controlled based on the actual situation of the target object and the instructions of the demagnetizer.

In summary, the principle of a demagnetizer is to generate a specific form of magnetic field to interact with the residual magnetism in the target object, thereby changing the direction of the magnetic moment and gradually eliminating the residual magnetism. In practical applications, appropriate demagnetization modes and parameters can be selected based on the type and remanence of the target object to achieve effective demagnetization.

ZC-227 power Transformer degaussing instrument is a specialized equipment for eliminating residual magnetization hazards after DC resistance testing of large power transformers. It plays an extremely important role in protecting power transformers from excitation inrush current impacts and ensuring safe operation. Due to the presence of residual magnetism, when the transformer is put into operation, the residual magnetism of the iron core saturates the transformer’s half cycle, generating a large number of harmonics in the excitation current. This not only increases the reactive power consumption of the transformer, but may also cause misoperation of the relay protector, resulting in certain economic losses. So we must do demagnetization work before the transformer is put into operation to ensure the safe and normal operation of the transformer.

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