In addition to the above, factor which contributes to increased power consumption is.
- Low power factor low input voltage
- Frequent failure of power supply.
- The asbestos thickness and rammed lining thickness, more than recommended.
- Heavily patched/ repaired furnace lining.
- Frequent emptying of furnace and cold starts.
- The average level of molten metal low in a furnace in operation.
The power requirement per tone of molten metal for different types of charge materials is as follows: (approx)
- Solid blocks: 500-550 Units (approx)
- Pig iron: 550-600
- C.I. scrap: 500-550
- C.I. Borings: 550-600
- Steel scrap: 500-550
- Steel Turnings: 550-600
It depends upon the cleanness of the material. A high percentage of mud etc increases power consumption.
For various combinations of charge materials, intermediate figure are application. In superheating, generally, 50 units per tone of molten metal per 1000C rise in temperature are observed. Also, the melting/superheating power consumption is higher per ton with smaller furnaces.