Harmonic control of castings, smelting, and the use of mid-frequency furnaces

Problem Description:

1. The main load is an intermediate frequency furnace. The six-phase rectifier bridge is a typical harmonic source.

2. As the transformer is overloaded, voltage distortion is caused, and harmonics are greatly increased.

3. The six-phase rectification control makes the rate of change of the current in the commutation process of the thyristor extremely large, the waveform of the entire load shows a right-angle change rate, the waveform coefficient is bad, and the harmonic distortion is serious.

4. When the power factor cannot meet the requirements, it is only caused by the poor form factor, and cannot be compensated by the conventional reactive power compensation equipment.

5. When the IF furnace is operating at full load, the current distortion rate is 24.5% and the voltage distortion rate is 10%.

Control measures: According to the actual situation of the site, install a AC Active Power Filter (ACTSine-100D) with a Leica compensation capacity of 150A in parallel next to the power distribution cabinet.

Control effect: When the intermediate frequency furnace is running at full load, the current distortion rate is reduced from 24.5% to 8.8%, and the voltage distortion rate is reduced from 10% to 5%, which greatly reduces the harmonic level.