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on emergency power




 
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Patrick J. / KD5OEI
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« on: July 14, 2014, 06:39:43 PM »

99 degrees today, big T-storm, power went out. 15 minutes later it is 70 degrees outside, not raining, and the power is still out. It's totally out for a few miles west, so we will see how long it takes.. I'm grateful for the 40KW diesel set in the back yard.
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« Reply #1 on: July 14, 2014, 07:26:29 PM »

Had a lot of bad sorms in this area the last few weeks, never any outages here though. This morning several counties in WV and MD were without power, I'm surprised we didn't get any storm-related damage calls (I work for a company that installs and repairs telephone systems and network cabling).
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« Reply #2 on: July 15, 2014, 06:39:14 PM »

The cause was a 12KV line down at the end of the street. It wa pulled down b a tree that also fell n a house there. It took them 20 hours to get to it and resotre power. Tank is 1/2 full, probably used 15 gallons of diesel. ouch $$ but I have an excuse now to buy red diesel for cheap since I am almost out of the road fuel.

The arcing as the line failed is likely what blew up a back to back zener diode arrangement in the transfer switch that was in series with a 208V relay to make it work on 240V. The relay is the one that drops out when the mains fails. It was still working but buzzing having 180V across it due the messed up diode. I have a proper 240V replacement, just a bit lazy getting to it.

About the arcing, the storm had already caused enough faults that the generator had started up and transferred power, one side of the 240V kept going out. So the household was isolated when the big zorching happened. The light from that could be seen coming through a window even though the arc was 200 Ft away. The poor relay is always across the external source though. A dirty job. I wonder how much of the neighbors stuff got burnt up.
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« Reply #3 on: July 21, 2018, 10:57:15 PM »

On emergency power again as of 5:44 PM!
110 degrees outside. Power went off. A great drill for the generator..
8:40 PM: power back on.

The pole transformer had failed. Well.. Hmm.. 25KVA unit serving 5 homes and the Bunkerof DOOM.  I think that's small. At least two of the homes have been bought by permanent owners and upgraded from the 2-3 small window units common in this neighborhood to decent/adequate central HVAC. Bunker HVAC also eats 6KVA when the unit's running - and the thermostat is set at 85 so it has been running some. My 3 ton unit has been running.. it uses 35-40A at 240V.


The failure was caused by the oil boiling or pressurizing the unit to the point of forcing its way out the side insulators or bushings (split 240V). The techncian says it arced and showed me a track. I did not know the low side would arc across leaked mineral oil. Whatever happened it popped the transformer.

It was a little distressing to see that the new transformer, although being rated 25KVA too, was only 60-70% the size of the old one, and it had no cooling fins on it as the old one did. They said they are putting a fuse on the new one.

These actions are of a contractor. They don't get to make decisions on KVA or anything else. They just do what the orders from the utility say to do. They did a great job though.

The trouble I see is that there is only 25KVA of transformer there and I can easily eat up much of it. Not sure what transformers cost but it would seem wiser to put in a larger one than replace it again. I'm told the high line is 13KV. Had thought it was 7200.. but it is a 10GA wire at least. Seems like plenty of capacity up top.

If anyone with distribution experience would comment, it would be very good to understand what is going on with apparently under-rated parts.

What is the way to suggest higher KVA supply without the utility presuming that we 5 homeowners should pay for it? We pay electric bills after all - and I guarantee the neighbors won't put in a dime.
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« Reply #4 on: July 22, 2018, 12:56:02 PM »

    This last Tuesday we had a tornado pass through two-hundred yards from my house.  My wife and I missed getting caught in the destruction, in our car, by probably fifteen seconds.  We were on the way home from work, just turned onto a road maybe three miles from the house, and right overhead the fuse cutouts on a pole blew off with a bang and a shower of sparks.  With a strong thunderstorm in progress I knew that something had just come down on the lines nearby, and sure enough, barely a quarter mile down the road all hell had broken loose; big trees down across the road, poles snapped, and a hopeless tangle of cables.  There was a pole on the outside of a bend, and when the big stuff came down up the road the sudden tension on the cables had yanked the cross-tree right off the pole and flung it into the front yard of a house.  It all surely happened right at the instant those fuses opened - fifteen seconds earlier and we would have been right there in our little Sentra.
    It took us four attempts, foiled by downed trees on the first three, to get to our house, hearts in our throats all the way, fearing we'd find a devastated home, especially when the third road we tried was blocked by tons of fallen wood only two-hundred yards from the house.  But, barely a twig out of place when we tried the fourth road and came around the corner.  Tornadoes are funny like that.  I was picturing my big maple in the back yard bashed through my roof right over my shack, with rainwater gushing all over my rigs.  So, we were twice blessed: in the car on the way home and when we arrived.  There but for the grace of God...as they say.
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« Reply #5 on: July 22, 2018, 05:54:22 PM »

I'm grateful for the 40KW diesel set in the back yard.

OM, please tell me how you managed to get a 40KW genset: are you in MARS?

Bill, W4EWH
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« Reply #6 on: July 22, 2018, 10:39:15 PM »

KD1SH - very glad your property and lives were spared. I hate tornados and have had some that were too close. The last time a tornado came within 5 miles, I believe the glory of God was revealed to me in a RADAR image banishing the whirling storm away from my home at which time it dissipated. That's what I believe happened, a glorious miracle alright. Some people say 'lucky', well it is a free country. Give credit where due though -I did not stand there and make tornados go away that's for sure.


W4EWH - A story behind that. Not in MARS, considered it but I had no suitable antenna at the time.

I got the generator and 175A Zenith transfer switch because a company was moving their office. The computer room used large, old rack-size minicomputers.

The new office was to be smaller and PC / X86 server type gear was to be used instead of the old machines. No generator was to be used but their large UPS was being moved to the new location to allow running for 'hours' they said.

I heard about the set from a guy I know who does physical plant maintenance in buildings and was told to offer them $1500 for the genset and transfer switch. Apparently he'd worked both sides of the deal because at the time I had the tilt bed wrecker show up for the genset, the transfer switch had also been disconnected and was at the dock!

On a power distribution note - the utility folks left the leaking transformer sitting on the curb. I guess someone will eventually pick it up -either the power delivery co. or a couple of hobbledehoys in a truck out for scrap.


* god protecting my house from the tornado.jpg (86.11 KB, 800x718 - viewed 41 times.)
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