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Topic Title: What does "450/750V" on a cable REALLY stands for?
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Created On: 24 September 2011 11:37 AM
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 24 September 2011 11:37 AM
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hidex1213

Posts: 6
Joined: 24 September 2011

Hey guys.
Please allow me to be honest first - I do not have any engineering background at all (tho I graduated with a biochem degree, that's very different) and found myself working in a electrical supplies company now.

I've been trying to look up the meaning of "450/750V" or "0.6/1kV" (ie. U0/U, according to some articles) on the cables that I sell (obviously we sell LV electrical products) but I've been given various answers...
Some say that the U0 is the VDC rating while U is the VAC rating; while the others say U0 being the operational (or "regular", I guess?) rating and the U being the peak rating.

Would anybody here please verify this for me?
I know it's probably a really obvious question but it's been bothering me quite some time...
Please help if you don't mind.
 24 September 2011 05:01 PM
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OMS

Posts: 19462
Joined: 23 March 2004

Voltage to earth rating and voltage between phases rating

Regards

OMS

-------------------------
Failure is always an option
 26 September 2011 01:56 AM
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hidex1213

Posts: 6
Joined: 24 September 2011

Thank you!
But there always seems to be a "magic" factor of 0.6 between U0 and U (300/500V; 450/750V; 0.6/1kV...)
so my follow up questions are...
Why 0.6?
What causes the discrepancy between U0 and U?
What about for a single phase power? would U0 = U?
 26 September 2011 10:40 AM
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OMS

Posts: 19462
Joined: 23 March 2004

The factor is actually derived from Square root of 3 ie 1.73 which is the relationship between U - line voltage and Uo - line voltage to earth

So for a common 3 phase system you have:

400/230 = 1.73

and 1000V /1.73 = 600V (approx) giving you the classic 0.6/1kV cable rating.

Regards

OMS

-------------------------
Failure is always an option
 29 September 2011 07:41 AM
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hidex1213

Posts: 6
Joined: 24 September 2011

Thanks!
I'll now go and google up what's line voltage and line-earth voltage.
Thank you!
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