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

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

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

(OP)
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!

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

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.

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

(OP)
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!

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

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.

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

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.

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