# Electric heating for glass melting furnace

Some furnaces use electricity for glass melting. Low voltage and high amperage power is passed through the molten glass through 2 molybednum electrodes dipped into the glass. The molten glass acts as a resistor (when current passes from electrode to another) and heat is generated which heats up the glass to the required temperature. A scott transformer and a thyristor control panel is used to control the power to the electrodes. I am trying to replicate this process in my glass melting furnace.I have little electrical knowledge. My question is 1. Why does this (glass) heating process have a requirement of low voltage and high amps. Although I am not sure but some users have suggested that a 9kVA load would be running at 60 volts and 150 amps.

• It's the resistance who is dictating the V/I ratio. – Eugene Sh. Jan 21 at 16:55
• ...so our conclusion is that the resistance of the molten glass must be relatively low, less than $0.5\Omega$ – Elliot Alderson Jan 21 at 18:58
• Is it not a problem for you that the glass must be melted in order to begin heating? If you've got it going and you're just adding glass, no biggie, but you'll need to premelt a blob to connect your electrodes I think, since solid glass is not very conductive. – K H Jan 21 at 20:46
• Glass is already melted in a furnace. The electric heating is for boosting temperature in already hot glass. So using melted glass is not a problem. The glass temperature before electric boosting maybe in the range of 1200 - 1250 deg and heating is required to take it upto 1300 deg C. What should be the ideal voltage and amperage range to heat glass at that temperature? I do not know the resistivity of glass at 1250 deg C. It is soda lime (bottle glass) Thanks to all the people who responded. Any further help will be highly appreciated – Anup Singhania Jan 22 at 10:30