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Author Topic: Circuit Breakers  (Read 18018 times)

trigzy

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Re: Circuit Breakers
« Reply #45 on: March 29, 2006, 03:17:52 AM »
My personal feeling is one should completely isolate a generator thats on stand by and switch the neutral. But this requires a second ground system.
Sorry - this is going to be a bunch of boring stuff about grounding/bonding and how it applies to the Canadian electrical code.

Doug,
        I dont see why you would need a new ground, you can use the same system ground, you would just have to bond the neutral & ground in the Lister....  I dont see how you would add a second ground without viloating that new ground only allowed for "separately dervied systems"rule.

Rule of thumb as I was taught in a "standard" system:

Transfer switch:

Switched neutral: Neutral Bonded in Generator (Generator obtains ground from system - bond for loads obtained from gen when operating from it)
Non-Switched Neutral: Neutral Floating Generator (Generator obtains ground & neutral when cord is plugged in - bonding obtained from main panel)


Steve
« Last Edit: March 29, 2006, 03:28:27 AM by trigzy »
Power Anand 24/2, Brushless 20kW, some other antique iron.
Vendor of AVR's, Small Clones of Yanmar Diesel and Honda Gasoline Engines

Doug

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Re: Circuit Breakers
« Reply #46 on: March 30, 2006, 08:48:45 PM »
Your right Steve your not supposed to do this "in a nut shell" in a home with one service but this is a case of two buildings and an isolated power system with an interconnection.

You ground once and bond everything else. But when you "Bond" the common in the ST head at its source

Fourth retype now.....

And I've read section 10 about 4 times now and I keep changing my mind.
I'm probably in the wrong here but I need to talk to an inspector regarding rule 10-208, 10-206 and 10-700.....

Sid. If your reading this whats your take?

Five....
Yup the same rules should aply, I do this at work and I should be able at home pending the ESA take.

Doug
« Last Edit: March 31, 2006, 04:03:29 AM by Doug »

trigzy

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Re: Circuit Breakers
« Reply #47 on: March 31, 2006, 04:46:01 AM »
Doug,
       I thought if I just waited to respond long enough that all the code book references would disappear.....  :-[
  I just memorized the "usual" requirements for "normal" systems, and the simple "don't dos" list.   I dont want to complicate things - I'm sure there are all sorts of things you "can" do.......  But I dont want any goofy orange outlets in my house ;)

Steve
Power Anand 24/2, Brushless 20kW, some other antique iron.
Vendor of AVR's, Small Clones of Yanmar Diesel and Honda Gasoline Engines

Doug

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Re: Circuit Breakers
« Reply #48 on: March 31, 2006, 09:22:58 PM »
No you bring up a good point.....

I can do this in an industrial setting doesn't mean its smart to try and do it like this at home.
I must admit the big 4/0 ground from the grid to the colon of the mine has spoiled me.

What was I saying about knowing what I'm doing with grounding and bonding lol????
Goofy is right.

Other ideas on the goofy list that didn't make it into print were:

Neutral resitors grounding system based on a Startco 325 relay....
Industrial lighting arrestors from a 4160 substation....
Solas transformer power conditioning....
Remote start and transfer wired into my sump pump UPS ( itself a refugee from a pack up power suply for closing brakers )

Doug

trigzy

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Re: Circuit Breakers
« Reply #49 on: March 31, 2006, 10:40:17 PM »
Doug,
       Whatever you decide to do...... let us know.  The sump pump backup is always good if flooding is a possiblility.  I was measuring ground on poles one day (using an interesting device constructed for that purpose)  H1 allows a maximum of 25ohms for a good ground.  Needless to say - I dont think I found even one that was under 75ohms......except in the transfomer station.  It's amazing what a couple thousand square feet of fence buried can do for your ground.... 
That same week, I was laughing at the guy working in the Transformer station when the Aug '03 blackout occured.  You should have seen the look on his face when I told him I was going home and to "have fun closing that 500kV switch BY HAND after you run down the station batteries"   I've never seen lights and computers turned off so fast in my life.

Steve
Power Anand 24/2, Brushless 20kW, some other antique iron.
Vendor of AVR's, Small Clones of Yanmar Diesel and Honda Gasoline Engines

Doug

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Re: Circuit Breakers
« Reply #50 on: April 01, 2006, 02:06:31 AM »
Nope I'm going to bond the neutral at the head on the line side of the disconnect like you said, like I should and run 3 pole transfer switch between the main and sub panel.

Ya priming a braker by hand can be a real bear.
I had to do the same a few months back on a 6900 braker because the universal motor fried when a couple of S&C fuses blew in what was suposed to be a ty-switch (that strangely had fuses in it not on the print GRRRRR).

So I spent 20 minuts ratcheting the springs and closed it only to find the SOB rattled hummed and did a funny little dance when when the remaining phase came to life some silly poop head (not exact words used at the time) didn't update the prints. Of course its pannic time too because the pumps that keep the mine dry won't run without power. Now those upper pumps are running but the deep pumps won't start and I found some creative stress cones in a 13.8 switch that couldn't take abuse now I have an S&C doing a funny little dance between me and the door of a tiny electrical vault. 18 hours I spent priming brakers, changing fuses and soiling myself LOL.

You know we're(by that I mean the power dept with me standing there looking like a dummy) suposed to check the ground grid and our 4/0 magic cable but I can't say I've ever seen it done. Thank god we use neutral grounding resistors on our 13.8 and down to limmit fault current. On the other hand you pray those protection systems will work but its always in the back of your mind there are brakers no one ever remebers seeing trip and a lot of the old stuff has no test.

I've been lucky some of this stuff is real old and abused.
Other fun and games with medium voltage:
"Why is everyone dragging their feet in here?"
Spud wrench impaling a 13.8 mine armour cable in the shaft is it live?????
35 year old cables subjected to hipot tests and returned to service then I get to close the switch
Personal fav standing ankle deep in water in flooding 4160 vault trying to get the pumps running ( I was green, stupid and did what I was told ). That was lots of laughs I had this realy attractive young cage tender with me and she says is there anything I can do? So said I stand on this plastic chair outside the switch room and If I fry call for help she stayed there scared poopless untill I fired up the pumps
Any one know how to use these new 3M splice kits ?
Hey these hot gloves expired last year.....
Phone call to No.1 sub " Can you tell me how to do a station guaratee? "
How long has that light that tells you we have a ground on that ungrounded delta been flickering?
What is this goo were standing in next to the Askeral filled transformer?
13.8 unshielded cable....  exists???

Its a learning curve, stops when you retire....

Doug
« Last Edit: April 01, 2006, 02:42:44 AM by Doug »

trigzy

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Re: Circuit Breakers
« Reply #51 on: April 02, 2006, 03:56:14 AM »
Interesting stuff Doug.....  but I will point out one thing you may have misread....

"closing that 500kV switch BY HAND"  isn't "Ya priming a braker by hand can be a real bear."

I'm sure priming those big breakers really sucks, but I'm talking a gaint 3phase, 500kV knife switch, OPEN AIR, basically 3  15 foot long bars.  Normally opened/closed electrically with no load and preferably no potential......

When operated manually, there is a 2 foot diameter wheel on the side of the switch.  They "trained" me to operate it.......   
"Whatever you do, whatever happens, just keep turning"
I guess the arc starts to form about 7 feet away if you are closing the thing, and take about 10 feet of open air when opening.....
And that's just to magnetize the transformer in the station...........now that's a little scary.
Aparently there have been "incidents" when the switchs bars dont meet the jaws..... and the whole damn thing welds itsellf half shut...

Delta stuff in commerical applications makes me a bit nervous.......  And what is "Askeral"??

Steve
Power Anand 24/2, Brushless 20kW, some other antique iron.
Vendor of AVR's, Small Clones of Yanmar Diesel and Honda Gasoline Engines

Doug

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Re: Circuit Breakers
« Reply #52 on: April 02, 2006, 04:10:50 AM »
Oh my by hand realy means by hand better him than me.....

Askeral was a type of PBC oil used in the old days. I'll be pumping it out of 40 year old junk as we replace them with dry types for the next 2 years. Nice O/T job suit up like the X-files suck the oil into drums and drag the corps up to surface.

Yup, I saw an ungrounded delta ossilate back about 16 years ago. No real hint of trouble untill ac motor drivesed started tripping on "DC bus over volt" and someone noticed the light out. Trouble is we couldn't shut down the transformer because the foundry furnaces were loaded. Voltage spikes were aproaching 800 Volts The ABB drives starting dying without a whimper. The Yasakwa stuff shut down before it failed but we needed them running to run the cranes to tap the furnaces.
Glad I was just the crane man, they lynched they guy responsible for the fault in the compressor plant

Doug