1000 VDC

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Mark Calabrese

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If i am running a 1000 VDC power system, would the insulation on the cable need to be rated for 1000 v or could I use 2 wires rated at 600v .. I know it seems strange
but I could not find the answer. and it seems that both wires would be carrying the same current and or the same voltage.
 
second part first. No you can't divide the voltage, to use a lower rated wire.
But wire are rate for AC circuits. so a 600 V RMS wire will see an 840 V peak.
 
995 VAC is still common in some coal mines. There is also a fairly uncommon 1200 VAC and 690 VAC sometimes with VFDs.

Either way you would typically use unshielded 2000 V insulation. There are a few wire types that support it, mostly mining types such as W, or DLO. GE used to do a lot of high power DC servo systems and made extensive use of DLO due to its flexibility.
 
Speedskater said:
second part first. No you can't divide the voltage, to use a lower rated wire.
But wire are rate for AC circuits. so a 600 V RMS wire will see an 840 V peak.
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It is DC hi potted to 200% of AC rating plus 1090 V or 2200 V. NEMA has done some surge tests due to the prevalence of VFDs and found the thinnest available motor insulation, #14 THHN with just 5 mils PVC tests to 2850 V surge. Still, it is not rated for that. Although the peak may be much higher the issue is that DC performance has to do with polarization and unless it has a DC rating you need to treat nominal AC and DC as one and the same. There is no guidance to somehow use higher ratings for DC. So 600 V is 600 V. Use the 2 kV stuff. It really isn’t that much more expensive or worth the risk. Partial discharge is far more likely given the conditions with DC.
 
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