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Induction furnace protection device
The main protection contents, setting reasons and methods of induction furnace are listed in the following table.
Protection name | Protection reasons and protection methods |
Cooling water temperature is too high | When the outlet water temperature of the cooling water exceeds the specified allowable value, scale is easily caused, and even water is vaporized, causing an accident. Therefore, at the outlet of each water-cooled pipeline, a charged water temperature gauge can be installed. When any water temperature at the exit of the cooling water circuit exceeds the allowable value, an alarm signal is issued. |
Cooling water pressure drop | When the water pressure of the cooling water is lower than the desired number, the cooling conditions will be destroyed. On the cooling water total inlet pipe, a water pressure gauge with a live contact is installed. When the water pressure drops below the allowable value, an alarm signal is issued and the sensor supply circuit is cut off. |
Over current, short circuit protection | Install a differential protection overcurrent relay. When an overcurrent or short circuit accident occurs in the main circuit, the main circuit is cut off and an alarm signal is issued. |
Undervoltage protection | An undervoltage relay is connected in front of the main circuit closing contactor. When the main circuit is powered off, the main circuit closing contactor automatically trips and has an accident signal indication. Re-closed the next time you call |
Phase C phase failure protection | At the outlet end of the balancing device, a phase C phase-phase protection relay is installed . When the C phase is cut off, the main circuit is cut off immediately, and there is a signal indication to prevent the resonant current from being generated in the balanced reactance and balanced capacitor circuits, and the balanced reactor and capacitor are burnt out. |
Protection name | Protection reasons and protection methods |
Limit the protection of the main circuit closing current | In the induction furnace, there are a large number of compensation capacitors and balancing capacitors, which generate a large inrush current when the switch is closed.Therefore, the main circuit is closed twice. First put on the start contactor with resistance, then close the working contactor, cut off the resistor |
Transformer oil temperature indication and gas protection | The electric furnace transformer has an oil temperature indication to monitor the temperature of the oil. Gas protection is also installed on the larger capacity electric furnace transformer ( above 800KVA ). When a fault occurs, the gas relay acts, the power supply circuit is cut off, and there is an alarm signal. |
Capacitor internal overcurrent protection | 3000V phase-shifting the frequency IF electric capacitors and capacitors, are also connected in the interior of the overcurrent protection fuse, when a failure of any of a set of capacitors, automatic removal of the group |
Leakage furnace and main circuit grounding protection | It is equipped with a 坩埚 alarm device. When the furnace or main circuit is grounded, the power is removed and an alarm signal is issued. |
Overvoltage protection | Install a voltage absorber on the secondary of the transformer to prevent overvoltage, over-voltage breakdown of the transformer, and overvoltage caused by lightning strikes. |
Capacitor discharge protection | After the main circuit is powered off, the capacitor must be discharged for safety. The capacitor is automatically discharged through the load, and the variable capacitor is automatically placed in the electrical resistance loop for discharge. |
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