What causes the induction melting furnace to fail to operate at high power?

The intermediate frequency power supply current of the индукционе пећи за топљење is very large, and the intermediate frequency voltage is half of the rated voltage. It is a bridge arm job. Look at the schematic below,

If the intermediate frequency voltage of the induction melting furnace can reach the rated value, the current is very small. This is because the load is too light. The material space to be melted in the furnace can be appropriately blown oxygen to quickly form a molten pool, and the power can go up after a few minutes; The voltage is low, indicating that there is a short circuit, check whether the insulation of the furnace body is damaged, and whether the KK is damaged.