Arc Furnaces 15 to 46kV and Greater Than 15MVA

Number of Switches Per Phase Control Transformer Control Voltage Control Part No.
1 5kVA at 3.5% max impedance or 10kVA at 7% max impedance 120VAC 1001711G13
2 10kVA at 3.5% max impedance or 20kVA at 7% max impedance 120VAC 1001712G13
3 15kVA at 3.5% max impedance or 30kVA at 7% max impedance 120VAC 1001713G13
4 20kVA at 3.5% max impedance 120VAC 1001714G13
5 25kVA at 3.5% max impedance 120VAC 1001715G1
6 30kVA at 3.5% max impedance 120VAC 1001716G1

The control to the left is for an arc furnace with 3000 amperes primary current at 15kV or 1500 amperes at 34/46kV.  It can operate nine switches total or three per phase. It is a direct replacement for a Joslyn™ arc furnace control. The control shown is representative of a whole range of controls available which are capable of operating from three to eighteen switch mechanisms. The control is modular for easy diagnosis and repair.

This control can minimize transient in-rush current either with resistor insertion switches or synchronous closing with the alternating current sine wave.

The control is operated by an Allen Bradley™ MicroLogix™ 1100 PLC. The PLC has diagnostics built into its PLC  program. The control can detect a switch mechanical malfunction and initiate an emergency trip so as to prevent single phasing of the furnace transformer.  Single phase power on a furnace transformer is a frequent cause of exploding arrestors.

The control has a reset function which can reset the control following an intermittent switch malfunction. This feature enables a furnace to continue operating without down time while deferring the maintenance on switches to a convenient down day.

The MicroLogix™ PLC  has an Ethernet connection for remote monitoring with a PanelView™ monitor. The PanelView™ monitor graphically displays individual switch open or closed status and maintains a date and time stamped log of switch malfunctions which resulted in the control being reset.

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