LV Cable Selection - Voltage Rating - Single Phase, 700V rms 1

[Instrument1352]

Hi,
I have an application where the supply is a "float" 700V rms, 50hz and the load is 50m away about 5kw, all at ambient temperature.
Normal power cables are rated 0.6/1kv which seem to be ok (0.6kv core-earth and 1kv core-core), however my concern is if a fault occurs and one of the cores is short to earth, then it would exceed the insulation rating of 0.6kv core-earth.
What exact cable would you suggest for this application?
Thank you!

 

[Kiribanda]

It looks like,
1)you are from IEC world
2)your 700V system is high resistance grounded

Based on above you have to select the cable designated as 1.8/3.0(3.3)kV.
To my knowledge there is no cable available between 0.6/1kV & 1.8/3.0(3.3)kV in the IEC/ BS world.

 

[Instrument1352]

Hi Kiribanda,
Having to use MV cable was my fear. Makes everything more difficult, from engineering, to procurement & installation and a whole lot of other head aches.
Probably I need to face my fate!

 

[RRaghunath]

IEC allows use of 600V/1000V cables for unearthed system as well, provided the protection scheme ensures automatic detection and isolation of earth faults in <1 min. There is some hope.

 

[7anoter4]

I am sorry, but I think IEC 60502-1/2004 recommends as maximum voltage Uo [line-to-ground] only 0.6 kV for 0.6/1.2 kV. For 0.7>0.6 it has to be 1.8/3 kV rated.