575V Three Phase System

[ed downey]

I haven't worked with many 575V 3 Phase systems but I had an engineer once tell me that I needed 1kV insulation on the conductors in lieu of 600V insulation. I cannot remember his reasoning for this. Has anyone else ever heard of this requirement?

-Ed

 

[CIECO]

Any 575 equiptment that I have see was done with 600V wire, fuses, disconects and panelboards.

 

[ron]

I also have seen it using 600V wire.
I wonder though, once there was a new 20MW plant that I worked on and since it was a relatively unloaded plant for the first 6 months or so, the voltage ran at 605V, and I lost a lot of sleep thinking that the voltage was higher than the conductor ratings. The POCO didn't want to adjust the primary tap on the substation, so it ran a bit high for 6 months. I guess luckily, the 600V rating is a conservative value from the manufacturer and the system seems okay.

 

[Smart $]

... I guess luckily, the 600V rating is a conservative value from the manufacturer and the system seems okay.

I believe the 600V insulation rating is a nominal voltage rating... just like the system you mention being a 600V system even though it is running at 605V.

I should also add that it is an AC RMS voltage rating. Perhaps the engineer Ed mentioned was but a pup in his field, thinking peak voltage on a 600VRMS system is in the neighborhood of 850V...