Inverse time breaker vs instantaneous

[Jraef]

Never have seen that one. What is the typical application for the 240 single phase it supplies? If you need 120 you are going to need another transformer anyway. Or is it just a way to avoid corner grounding?

When you need a delta supply for some reason and you want 240V single phase for lighting.

 

[Joethemechanic]

When you need a delta supply for some reason and you want 240V single phase for lighting.

Is it normally done full delta, or open delta?

 

[Jraef]

Is it normally done full delta, or open delta?

I've only seen one in 40+ years in this industry, it was open delta.

 

[kwired]

Never have seen that one. What is the typical application for the 240 single phase it supplies? If you need 120 you are going to need another transformer anyway. Or is it just a way to avoid corner grounding?

Avoiding corner grounding I guess, though the high leg is still 416 volts to ground. These usually serve limited load that is or almost is entirely three phase load. Around here mostly is irrigation systems supplied by this. Most with fair load amount are 480/277, but some lesser load applications you will find it derived via open delta bank

If you need 120 volts on a 480/277 system you also need another transformer so that part isn't really a factor.