Three reasons for the damage of capacitors in medium frequency induction melting furnace and maintenance methods

 The electric heating capacitor is used to compensate the reactive power of the intermediate frequency electric furnace. Due to the high voltage and high current working state in the intermediate frequency electric furnace, the reactive power electric heating capacitor needs to be water cooled, and should be carefully maintained to ensure normal working conditions. The main reasons for the damage to capacitors in the maintenance of medium frequency induction melting furnaces are as follows:

1. Intermediate frequency electric furnace overvoltage:

1.1 The lining is thick:

As a result, the load becomes higher, the power becomes smaller, and the capacitor voltage fluctuation increases.

1.2 The furnace is too fast:

In the short time after tapping, there is no molten steel in the furnace, short-circuit discharge between the charge, causing the frequency current to flash, the drift of the load resonance point is large, and it is easy to cause the short-term inverter angle to be too large, the inverter voltage Instant rise

1.3 The charge is too bad:

During a period of time after the start of the furnace, the current and frequency are very low, and the energy of the DC reactance continuously charges the capacitor. If the load becomes lighter, the low-frequency oscillation of the capacitor increases, which tends to cause the capacitor to over-voltage in one direction.

2 . Medium frequency electric furnace overheating:

2.1 The cooling water is unqualified:

The scale will cause insufficient heat dissipation, the temperature difference of the capacitor core is large, and the center withstand voltage is lowered. Insufficient water flow will cause the overall temperature rise of the capacitor to be high. Too strong corrosiveness will cause local leakage of the water-cooled coil, and the cooling water will mix with the insulating oil, resulting in greatly reduced insulation capacity.

2.2 Conductive pile head loose:

Due to the large current, the electric heating capacitor leads to more pile heads. Due to the alternating hot state of the work and the cold state of the steel discharge, it is easy to cause the pile head to loosen. The tightening screws need to be checked regularly.

2.3 The ambient temperature is too high:

The environment is poorly ventilated, and the ambient temperature is too high. Because the water-cooled coil is close to the capacitor casing, the heat absorbed by the casing is also carried away by the coil, which reduces the cooling capacity of the water-cooled coil.

3 . Medium frequency electric furnace over current:

3.1 Super frequency: The current of the capacitor is proportional to the frequency. The capacitor is usually damaged when it is full of molten steel. Because the frequency is the highest when the furnace is full, the current is the largest.

3.2 Capacitor short circuit: A short circuit of a capacitor will cause short-circuit discharge of surrounding capacitors, resulting in an instantaneous large current.