DC-GFP/2 protection [RE-wrenches]

Todd Cory, Mt. Shasta Energy Services toddcory at finestplanet.com
Fri Aug 23 15:38:11 PDT 2002


Bill Brooks wrote:

> Another one of the issues with an ungrounded system is that it still must
> have a method to reference it to ground potential. You can't have a module
> operating at 5000 Volts sitting next to a module frame at ground potential.
> It will flashover and cause a big mess as well as potentially energize the
> array frames if the ground gets loose. Somehow you must limit the
> differential from an electrical insulation point of view.

Bill, I am not sure I understand the statement above. Why do ungrounded systems
need to be referenced to ground? If it is ungrounded the 5 kV you mention above
will be with respect to *ONLY* the other conductor. It will NOT "flash over" to
any other thing just because it is metal or grounded. That is the beauty not
having any conductors grounded. The potential only is between the 2 conductors.

With an ungrounded system, the only way you could get a shock is if you touch
both conductors at the same time, or if (like is foolishly done in this country)
one conductor is grounded. Then when you are standing on the earth you are in
contact with one conductor. This seems much less safe than a system that is
totally floated and thusly insulated from people (who usually stand on the
earth).

I have heard our wonderfully "safe" grounded conductor system was implemented to
sell more wire and the labor to install it... and has nothing to do with
"safety".

Todd

- - - -
To send a message: RE-wrenches at topica.com

Archive of previous messages: http://www.topica.com/lists/RE-wrenches/

List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm

Check out participant bios: www.mrsharkey.com/wrenches/index.html

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com

==^================================================================
This email was sent to: michael.welch at homepower.com

EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Qcs.bz9JC9
Or send an email to: RE-wrenches-unsubscribe at topica.com

T O P I C A -- Register now to manage your mail!
http://www.topica.com/partner/tag02/register
==^================================================================





More information about the RE-wrenches mailing list