About the harmonics generated by the operation of the intermediate frequency furnace

The intermediate frequency furnace will generate a large number of harmonics in the production process, and these harmonics are very harmful to transformers, voltage switches, and production safety.

The harmonics of the intermediate frequency furnace will pollute the harmonics of the power grid, which will reduce the power transmission efficiency, cause insulation aging, and reduce the service life and other faults.

The following will be edited by Hongteng to introduce the harm of the harmonics of the intermediate frequency furnace to the transformer.

Harmonics increase the copper losses of the transformer, including resistive losses, eddy current losses in the conductors, and stray losses outside the conductors due to leakage flux.

The harmonics also increase the iron loss of the transformer, which is mainly manifested in the increase of the hysteresis loss in the iron core. The worse the harmonics make the voltage waveform, the greater the hysteresis loss.

Due to the increased loss in the above two aspects, the actual use capacity of the transformer should be reduced, or the harmonic content in the power grid should be considered when selecting the rated capacity of the transformer.

In addition, harmonics also lead to the increase of transformer noise. The vibration noise of transformers is mainly caused by the magnetostriction of the iron core. With the increase of the harmonic order, the components of the vibration frequency around 1KHZ increase the mixed noise, sometimes Also makes a metallic sound.

When the capacitor bank loop impedance is capacitive, the parallel capacitors amplify the harmonic current, especially when the system equivalent inductive reactance and the capacitor bank loop capacitive reactance constitute a resonance condition, and when current resonance occurs, even a small harmonic current It will also be amplified several times, resulting in a sharp increase in the loss of the capacitor, causing overheating or damage to the capacitor.

In addition, the increase of the harmonic voltage value increases the loss factor and additional loss of the capacitor, resulting in easy failure and shortening the life of the capacitor.

Harmonic Harm Control Measures

In actual production, we can use controllable power semiconductor devices to input currents with the same amplitude and opposite phase to the original harmonic current into the power grid, so that the total harmonic current in the power grid tends to zero, so as to achieve real-time compensation for harmonics. the goal of.

There is also a way to suppress it by installing a static reactive power compensation device, and installing a static reactive power compensation device in parallel at the harmonic source can effectively reduce the amount of fluctuating harmonics. At the same time, it can also suppress voltage fluctuation and voltage flicker, and can also compensate for power factor.

This is our introduction to the harm of harmonics to transformers in intermediate frequency furnaces today.

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Video of the use process of the furnace