Discussion thread regarding Schematics for the Constant Wattage [CW] type Isolation Transformer Ballasts, for single / dual operation of Mercury Vapor [MV], or Metal Halide [MH] lamp[s].
These Schematics are found in the Technical Reference Area, under the topic heading: HID Ballasts Schematics: CW 1 and 2 lamp
Fig. 4.1. = Constant Wattage Isolation Transformer with multi tapped primary, for 1 lamp operation,
Fig. 4.2. = Similar to Fig. 4.1., except for series operation of 2 lamps.
Both can be used to drive either Mercury Vapor, or Metal Halide lamps. The series 2 lamp arrangement requires use of similar lamps [e.g. 2 400 watt MH, or 2 400 watt MV].
Both have multi input voltage capabilities, which do not require the common conductor to be the system's grounded conductor - due to the isolation of primary input from secondary windings / lamp sockets.