Welding machine power supplies are classified as either Constant Current or as Constant Voltage types. In Constant Current welding machines, the output voltage is varied to maintain a steady current during welding. For safety, the voltage is usually kept lower before the electrode and the job are brought into contact. As soon as welding starts, the in-built voltage regulator increase the voltage to maintain the current required during welding, but as soon as the welding is completed and when no more current is being drawn, the voltage has to be brought down, and quickly. The time during which current is being used for welding and the time during which no current is being used can be sensed using special Magnet Sensors strategically located to sense current in the high-current cables. When the welding of the job is completed, and current start dropping, the Magnet Sensor signal triggers the controller which then reduces the voltage to lower levels. Suitable products are MS-324 or MS-328 flat pack sensors.