Power Supply Schematic
Upon tripping, the TDR feeds 120VAC to the coil of a double pole single throw high-current relay. Each pole of the relay carries a 120VAC leg of the 240 mains. Once tripped, one 120VAC pole from this relay is tapped to feed a 28VDC high current SPST relay power supply made with some 25watt cement power resistors, a 1N5408 diode and an electrolytic capacitor. Using the resistance of the relay coil as part of the calculation, with an appropriate ohmage value this circuit also serves to time-delay the 28v relay long enough (~ 1-2 seconds) to provide a soft-start for the HV transformer (which is why this relay is necessary). A solid-state TDR would also work if you have one. In the interim, as soon as the DPST high current relay trips, R2 (an Ohmite 25w 50ohm wire-wound) shorts the 28V relay contacts and provides a limited mains load to the filter capacitors for the length of the delay. After the 28V relay trips, R2 is bypassed & full 240V mains flows to the HV transformer.
RF Deck Schematic