Thanks for the reply k7elp60,
That's a good solution to the problem.
Like you said have one resistor as part load & then switch the parallel resistor on to create full load.
Just so I understand better.
So the SCR has to take the 500v max.
I have a (SEMIKRON SEMIPACK-1 SKKT 57/12 E) SCR, could I get someone to verify the Datasheet & make sure it is suitable for this application.
Is it suitable for DC switching, it has an AC symbol on pin 1 input.
EDIT;
I just had a look at the graphs on the datasheet, which I neglected to do before & it appears that it will switch DC as well as AC, is that correct or do I have it wrong.
Cheers