mmm, if the PSU is a true PWM PSU, the current returns are independant. they are suppose to be floated. you can try and measure for connectivity between the +/- pin to L, N and E. there should be more than 1M ohm resistance. each will sink its own amt of return current.
also, u can try the circuit with 0.5ohm (r1 r2) ... pump them into a bare heater bed and measure the voltage across R1 and r2 to check how it balances first before operating it fully. r1 and r2 will get very hot, so this test is for short period.
NoobMan Wrote:
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> And what about the gnd line balancing. Without
> that, you will be having amps from both sources
> sinking in only one psu gnd (whichever provides a
> better path). One of the gnd lines may get a
> current much above its rating. Perhaps most gnds
> have a good safety margin so this isnt too bad in
> practice, but it doesnt mean its correct. Probably
> at very least some track may heat up, and in
> extremis this *can* be worse.
also, u can try the circuit with 0.5ohm (r1 r2) ... pump them into a bare heater bed and measure the voltage across R1 and r2 to check how it balances first before operating it fully. r1 and r2 will get very hot, so this test is for short period.
NoobMan Wrote:
-------------------------------------------------------
> And what about the gnd line balancing. Without
> that, you will be having amps from both sources
> sinking in only one psu gnd (whichever provides a
> better path). One of the gnd lines may get a
> current much above its rating. Perhaps most gnds
> have a good safety margin so this isnt too bad in
> practice, but it doesnt mean its correct. Probably
> at very least some track may heat up, and in
> extremis this *can* be worse.