## here in Canada and the usa, the 240 vac is BALANCED. In Canada +
usa, the
12.5 kv / 14.4 kv single phase input to the is UNBALANCED. In the event
of a primary
to secondary short in the single phase xfmr, the sec needs to be grounded
some where
....hence the grounded CT on the sec. In fact the CT on the sec is
looped back to the
Grounded side of the xfmr pirmary..and done right at the xfmr.
Yes, you can. All up and down major roadways here. This is the root of my
concern expressed a few days ago. And, IMHO, it's a failed system due to
the potential for dangerous HV primary current to flow on an exposed
grounding conductor on a utility pole.
Where as a kid who used to use such conductors for the grounding of crystal
sets, I had not realized at the time the potential death trap set up by the
MGN distribution. It's a miracle that more cases of harm are not reported
as kids and animals make contact with the utility pole grounding conductor.
Safety is wholly dependent on crew maintenance to ensure adequate
distributed grounding of the MGN strand up and down an easement. However,
the problem is real. See this link for a detailed examination of what I'm
describing:
http://www.ecs.csun.edu/~bruno/MultiGroundedNeutralFinal_4-17-7.pdf
Note a few figures:
Fig. 2 - The MGN set up on the white/grounded conductor.
Fig. 3 - The exposed grounding conductor from the utility MGN.
Fig 10 - The original correct pole mounted wiring scheme from ca. 1926.
Fig. 13 - The "deadly" bond that VE7RF describes.
Fig. 17 - The classic MGN structure of a split-phase residential
transformer.
Fig. 18 - Primary HV fault can enter the home in a MGN system.
Fig 20 A proper method of bringing the primary back to ground while
achieving safety isolation and primary-to-secondary fault protection.
Paul, W9AC
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