Safety grounding in hazardous voltage DC systems ( 400VDC )

[masa6614]

Hello all,

Can you please help or direct me to any proper grounding requirements for dealing with a 400VDC system, specifically for a motor control system.

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http://i.imgur.com/N62tmew.jpg

)

So I've got a 400VDC brushless motor that needs powering, and I've purchased a AC/DC power supply to generate the 400VDC from 208VAC 3ph wall power. The output is isolated from earth (chassis) ground and I tap off of the output to a small DC/DC to generate isolated 28V for control power.
What I'm not sure of, are the safety requirements for dealing with this high voltage DC. Should I keep the power and return lines completely isolated from chassis?
The 28V power I'm sure eventually gets tied to chassis through a PC ground.
I was thinking maybe I should tie the 400VDC power and return lines to chassis through a large (>1Meg) resistor, in the event that if someone accidentally touches one of those live wires, the likelihood is they themselves are grounded and the current path is then limited through the resistor (400VDC/1Meg). Another concern is what happens if one of the high voltage lines ends up coming into contact with the it's chassis grounded enclosure?

Thank you!

 

[SceneryDriver]

Could you not derive your 28v power from an AC line-connected power supply? That would solve your inadvertent ground through the PC problem. As for the 400vdc source, is it more than a 3ph rectifier pack with filtering? Wouldn't it be referenced to ground, or is there a set-up transformer within your power supply?

If it's not ground referenced, something like this could be an option:

http://www.bender-us.com/products/product.aspx?p=IRDH275

SceneryDriver

 

[masa6614]

Thank you, that ground fault device looks like what I'm looking for.
The 400VDC power output is transformer isolated from the 208VAC.
Also, while searching, I found that the military has a 270VDC power specification (MIL-STD-704) which ties the 270VDC return to the 28VDC and Chassis at the source.
But I also found another military specification for +/-300VDC power (MIL-PRF-GCS600A) where the +/-300VDC rails are tied to Chassis through resistors and monitored for ground faults that way.