Independent 30V 10A Power Supply question

[maheshkuruganti]

Earthing Question

I have to make a Independent 30V 10A Power Supply. It has to be such that we should be able to Series and Parallel for more Voltage or Current. Now That is simple enough. But I now Earth the chassis and also the Secondary of the Transformer.This would then rule out any combination so my question is should the Secondary of a Transformer be Connected to Earth or not.Please tell me whether I should ground only the chassis or both.Thank You

P.S:I use a metal case.:

 

[FvM]

Earthing Question

The chassis and e.g. the transformer core should be connected to protective ground, but the secondary must be isolated for a laboratory power supply. A double isolation of the primary voltage is required for safety reasons. Also series connection of individual units must pay attention to isolation voltage ratings and safety rules. DC voltages above 60 V are considered dangerous and require protection against accidental contact.

P.S.: IEC 1010 respectively EN 61010 is the respective safety standard for laboratory instruments. A technical university should have it accesible in the library.