Basic question about dielectric ratings for wire

luvdunhill · 3rd September 2007, 11:55 PM

well, this is a rather basic question. Say I have two +-400 VDC lines, each of which are running on a cable that is rated to 600 VDC. Is it safe to run these cables right next to each other for a few feet inside of a umbilical-type power cable? I would assume so, since the total potential is 800 V and each cable can contain its own share of the 400 V...If I wanted to be extra cautious, would placing the cable in teflon tubing be one way to go, or totally not necessary?

Thanks!

BWRX · 4th September 2007, 12:50 AM

According to this link http://www.motioncontroluniversity.c...agerating.html

"The specified voltage rating is defined in relation to the conductor and an adjacent item. For example, the single conductor has the insulation rated between itself and any other device (shield or other device capable of developing a voltage potential) and the outer jacket has no insulation rating recognizable by UL and therefore cannot be considered as a factor in the rating. According to UL, it is just a protective and binding element."

So, the answer to your first question would be yes. 1200V would be the maximum allowable potential difference between the conductors of two wires that both have 600V insulation ratings. Putting teflon between them would expensive and unnecessary. If you want to be extra cautious you would either physically separate each wire or install another layer of insulation around each wire where they run in close proximity. I would opt for another protective layer of insulation.

AndrewT · 5th September 2007, 04:46 PM

Hi,
in the UK we use twin and earth.
the live and neutral are insulated and the earth is uninsulated.
Each core insulation must meet the voltage requirement between core and earth. Even if the two cores had opposite phase on them their core to earth insulation would ensure that core to core worst case also complied.

However, add an extra outer insulation. This provides physical protection to the main core insulators ensuring they stay up to specification. All our mains cables must be double insulated when outside a protective enclosure.

3rd September 2007, 11:55 PM	#1
luvdunhill diyAudio Member Join Date: Jul 2006	Basic question about dialectric ratings for wire well, this is a rather basic question. Say I have two +-400 VDC lines, each of which are running on a cable that is rated to 600 VDC. Is it safe to run these cables right next to each other for a few feet inside of a umbilical-type power cable? I would assume so, since the total potential is 800 V and each cable can contain its own share of the 400 V...If I wanted to be extra cautious, would placing the cable in teflon tubing be one way to go, or totally not necessary? Thanks!

4th September 2007, 12:50 AM	#2
BWRX diyAudio Moderator Emeritus Join Date: Jan 2005 Location: Pennsylvania	According to this link http://www.motioncontroluniversity.c...agerating.html "The specified voltage rating is defined in relation to the conductor and an adjacent item. For example, the single conductor has the insulation rated between itself and any other device (shield or other device capable of developing a voltage potential) and the outer jacket has no insulation rating recognizable by UL and therefore cannot be considered as a factor in the rating. According to UL, it is just a protective and binding element." So, the answer to your first question would be yes. 1200V would be the maximum allowable potential difference between the conductors of two wires that both have 600V insulation ratings. Putting teflon between them would expensive and unnecessary. If you want to be extra cautious you would either physically separate each wire or install another layer of insulation around each wire where they run in close proximity. I would opt for another protective layer of insulation. __________________ Brian

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Question about Allied & Hammond Power Transformer Ratings	Bitrex	Tubes / Valves	2	6th March 2009 07:31 AM
Dumb question on Coupling cap ratings...	john65b	Tubes / Valves	9	18th October 2008 01:26 PM
Newbie Question on Driver Ratings	6f6	Multi-Way	3	14th January 2007 11:58 PM
Newbie question regarding fuse's and resistor ratings	neil_kaye	Parts	7	2nd July 2006 07:29 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

5th September 2007, 04:46 PM	#3
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, in the UK we use twin and earth. the live and neutral are insulated and the earth is uninsulated. Each core insulation must meet the voltage requirement between core and earth. Even if the two cores had opposite phase on them their core to earth insulation would ensure that core to core worst case also complied. However, add an extra outer insulation. This provides physical protection to the main core insulators ensuring they stay up to specification. All our mains cables must be double insulated when outside a protective enclosure.