Supply rail to UV print head increased to minus 230VDC..Precautions?

[treez]

If an ultraviolet print head for a curing machine has a 100W bank of leds on it supplied by a Buck converter LED driver from a 48V rail…then what extra safety precautions need taking if the rail is made to be minus 230VDC?
(That’s an ‘isolated-from-the-mains’ -230VDC).

The leds are in Buck connection, with the anode to the 0V rail, so the actual led voltage is never more than 50V above earth ground, even though they are supplied from the output of a –230VDC SMPS.

 

[betwixt]

I assume you mean they are rewired so they run on 230V DC instead of 48V DC.

The polarity should make no difference as long at it's what the LEDs are wired to work from. The increased voltage makes no difference as long as you observe sensible safety precautions against exposed parts being touched and you have insulation that can withstand 230V. I would assume that there were already barriers and safety locks in place when such high UV radiation is present.

Brian.

 

[treez]

Thanks, I suppose that also, the safety insulation for 230VDC is the same as far 230VAC RMS mains?

 

[betwixt]

230V DC is just that. 230V AC peaks at (230 * 1.414) = 325V so for insulation purposes DC is less demanding. You should still ensure it is 'finger proof' though, DC in some circumstances is more harmful than AC to human tissues. I would advise a safety lock that kills the power if access to the system is needed. You should have one already to prevent over exposure to the UV light.

Brian.

 

[D.A.(Tony)Stewart]

I imagine is there is an open fault, the voltage will rise above 50V on the high side.