Analysis of Safety Protection System of Induction Melting Furnace

1) The circulating water system is the core concern in the normal operation of the complete set of induction melting furnace equipment, which can be focused on from the following two points.

A. The cooling water temperature is too high

In the induction melting furnace system, when the outlet temperature of the cooling water exceeds the specified allowable value, it is easy to cause scale, and even vaporize the water, causing accidents. Therefore, it is necessary to install a water temperature gauge at the outlet of each branch water cooling pipe. When the water temperature at the outlet of any waterway exceeds the allowable value, an alarm signal will be sent back to the intermediate frequency power control system, and the machine will be shut down in time to prevent accidents.

B. Cooling water pressure drops

When the water pressure of the cooling water is lower than the required number, the cooling conditions will be destroyed. An electric contact water pressure gauge is installed on the cooling water main inlet pipe. When the water pressure drops below the allowable value, an alarm signal will be sent back to the intermediate frequency power control system, and the inductor power supply loop will be cut off in time

2) Protection measures for the main circuit system

A. Over current, short circuit protection

Install a differential protection over-current relay, when an over-current or short-circuit accident occurs in the main circuit, it will automatically cut off the main circuit and send out an alarm signal

B. Undervoltage protection

An undervoltage relay is connected in front of the main circuit closing contactor. When the main circuit is de-energized, the main circuit closing contactor will automatically trip, and there will be an accident signal indication. When the next call comes in, reclose

C. Overvoltage protection

Install an overvoltage absorber on the secondary side of the transformer to prevent operating overvoltage, transformer primary and secondary side breakdown, and overvoltage caused by lightning strikes

D. Capacitor discharge protection

After the main circuit is powered off, for safety reasons, the capacitor must be discharged. The capacitor is automatically discharged through the load, and the variable capacitor is automatically placed in the resistance circuit for discharge.

3) Transformer oil temperature indication and gas protection

The electric furnace transformer has an oil temperature indicator to monitor the oil temperature. Gas protection is also installed on the larger capacity electric furnace transformer (above 800KVA). When a fault occurs and the Buchholz relay will act, the power supply circuit will be cut off and an alarm signal will be issued

4) Crucible leakage furnace and main circuit grounding protection

It is equipped with a crucible alarm device. When the crucible leaks out of the furnace or the main circuit is grounded, the power is cut off and an alarm signal is issued