Mercury Arc Rectifier

Type Hewittic 150/6 24102 Mercury Arc Rectifier. Made in England.
6 wire AC input, DC comes out the bottom, the negative is 0v from the ac transformer.
To operate small excitation is obtained within the mercury pool, a single small aux arm via solenoid dips into the mercury to initiate a small excitation arc.
Further stability is obtained by constantly running the 2 smaller aux anodes to prevent dropout.
The main current is the 6 big Anodes down to the mercury pool.
Current passing through the mercury vapour can only travel in one direction, thus creating forward current only.
The heat rises to the big envelope and condenses the mercury and it runs back down into the mercury pool.
Assumed to be operating 600v 150A