I worked on an old Dow plant that was originally supplied by an ungrounded service. All of their MCCs used fuses as the OCPD. When it was converted to a corner grounded system, actual "dummy fuses" were installed in all of the buckets.
This happened with busway units also.
(1) Substitute word "netural" with grounded conductor for the corner grounded system.
Which, the dummy or the fuse?
One human, several fuse.
Something must have got lost in translation, or they are an item restricted to authorized dealers.
Yeah much less expensive I believe.
Which one do you want? I'll check my good stuff.
I would just call that 3-wire two phase not corner grounded, I have never seen a 3-wire two phase system in Philly only a 5-wire 240/120V, however I don't doubt you saw one.
For the same reason they haven't outlawed that polluting and unsafe 1965 Corvette that's already been made, but no longer legal to be produced new.
What is unsafe about it? The only thing I see is problems when unqualified people work on it.
They're used for running huge motors from single phase motors in SWER setup fed from a three phase grid. I'm talking several megawatt size motors.
www.hitachienergy.com
Correction on 1. If you want to switch the grounded conductor you use a three pole breaker/switch/contactor.
several fabricated ones? That is just about all I have ever seen in person. usually some sort of copper tubing. 3/4 copper tubing is "close enough" fit in a 30A 600 volt fuse holder.
The rural utility company I work around the most doesn't have any corner ground systems that I am aware of. They made an effort back in the 80's maybe into the 90's to eliminate all of them. Many irrigation services had such a supply. This was a cooperative and publicly owned utility (still is) and part of the benefits of such ownership was they would bring the service conductors out to the equipment served. With irrigation it often was maybe 1500 feet from the source. They didn't do it for free but were doing it for less than any contractor would charge to do the same thing. Little story to understand the situation here. The problem they created when they decided to get rid of corner ground delta was you needed a fourth conductor. Most those long runs I mentioned they buried a fourth individual conductor in the neighborhood of 10 to 20 feet away from the other three for most of the run. This not only creates more impedance during a fault condition but a problem I have run into in more recent years is when locate requests come in for other excavating this fourth grounded conductor doesn't get located and the excavator plows through it not knowing they hit it. I happened to find this when I was locating a underground problem with one of the ungrounded conductors one time more recently. In that process I discovered the grounded conductor was lost as well. End result was it was about 10-15 feet from the other conductors so I knew it was likely a system converted from corner ground delta, the break was right where a fiber line had been plowed in maybe 10 years earlier. My best guess they located the ungrounded conductors using simple 60 Hertz detection function of a locator and had no idea the grounded conductor was not in same vicinity so it was never marked. Makes me wonder how many other of those done like that had been compromised because of other excavation activity and failure to locate said grounded conductor.
