Some questions about a terminal block voltage and maximum ratings

Question

A screw terminal distribution block is shown below:

A three phase motor driver manual specifies "connector voltage" and current for mains voltage connections for the motor. They specify current as 30A and voltage as 1000V.

Imagine I use a screw terminal block as a connector as following:

^{simulate this circuit – Schematic created using CircuitLab}

1-) What does 1000V voltage rating mean for a connector or a terminal block? Is that something to do with isolation break down voltage between consequent terminals?

2-) The rms voltage difference between R and S is 230*sqrt(3) = 400V rms. This means 560V amplitude and this is half the 1kV requirement. Can 1000V requirement be about transients?

3-) What if I connect R S and T further apart for example every three terminals(not adjacent), would I increase isolation voltage?

Answer 1

1. The voltage rating for a terminal block is generally the RMS or DC voltage rating. The breakdown voltage would generally be higher for both consequent terminals and terminals a to steel mounting surface. I believe the terminal block may need to pass a test for something like twice the rated voltage plus 1000 volts. For a 1000 volt terminal block that would be a 3000 volt test if I am recalling the standard accurately.

2. I believe transient voltage is included in the breakdown voltage test.

3. You can increase the terminal to terminal rating by using every other terminal, but the terminal block may then need to have additional mounting surface insulation. Both of those could cause difficulty with testing laboratory listing. You would need to have the specific use examined rather than relying on the listing for the terminal block.

I don't have any reference to verify the above. If is is correct for USA standards it may not be correct elsewhere.