Metal tank type: to be used as a separate reactor and the tank should be grounded. Such reactors can be placed next to a wall (and even can be placed outdoors) to save space. When it is placed out of door, a bushing is used to transmit the high voltage into the lab. Metal tank reactor can also be used in series or in parallel connection. When it is used in series connection, insulated support is needed. The reactor can be designed with taps. Metal tank type reactor can be used for continuous operation.