Power Brown Outage

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Power Brown Outage

Postby zetreque on October 15th, 2014, 1:26 pm 

Last night I was sitting downstairs and for roughly 120 seconds the lights flickers and dimmed. It was the start of a bad Halloween movie.... Actually it wasn't, but one of the longest brown outs I have ever experienced. After the lights flickers and appliances went on and off the power stabilized in a really weird situation. The refrigerator had power, but wouldn't run. All of the lights were at half brightness, and some of them wouldn't even turn on.

I went outside and rather than chance burning up some appliances with this strange power, I shut off several breakers in the house, unplugged a few things, and switched my computer to battery, and eventually just went to bed.

I left one light on in my bedroom, so that it would come on when the power was fully restored and wake me up so I could go back outside and turn the breaker on to the refrigerator and furnace.

(It was a monster wind storm last night, and the news currently just talks about many outages all over the northern state, but no details. In any case, it was pretty cool listening to the intense winds all night. One strong gust almost had me stand straight up in bed from a dead sleep as it pounded the windows with tree branches breaking off)

The power was at this "half" power stage for 4 hours.

So what causes this strange power state? It was as if a phase was out, but I know that normal power isn't 3-phase. Would it be something to do with the cycles? 30hz instead of 60hz? Or, is it just not enough voltage coming through? Maybe just one of the lines was knocked out rather than a whole pole?
I didn't feel like testing the power last night with my multi-meter because I was too tired to chance screwing it up by not thinking clearly, and since I recently just purchased new fuses for it.
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Re: Power Brown Outage

Postby Dave_Oblad on October 15th, 2014, 4:57 pm 

Hi zetreque,

You did right by killing power at the breakers. You may have saved yourself a bunch of money on repairs. Many of today's appliances use Micro Computers. TV's, DVD Players, Cable Boxes, Microwave Ovens, Clocks, Washing Machines and regular Computers of course. Computerized products can be off or on and are designed to handle the transition between both states. In many, like TV's and Cable Boxes, the device is never really turned off, just some of the internal sections get shut off to reduce power consumption.

But Brown Outs are because some section of the Power Grid is pulling too much power and the isolation breakers are not operating properly, or Power Transformers have partially blown and not producing full output voltage but not drawing enough power to kick out the safety breakers.

In any event, operating any device that has a computerized controller build-in, at partial power, is very very bad. It can scramble and lose control of the various sub-sections under its control. Many electronic components draw extra power when in a quasi on/off power state and can blow themselves or other sections of the circuits.

The company I work for gets products returned for repair more often due to brown-outs than any other reason, followed by power surges, such as lighting striking near by or from cloud to cloud. Products returned for repair due to a simple component failure are actually rather rare.

Regards,
Dave :^)
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Re: Power Brown Outage

Postby zetreque on October 15th, 2014, 5:18 pm 

Thanks Dave,

It sounds like it was most likely a low voltage situation. I am really curious about the amount of money last nights 4 hour low voltage outage cost. In the section I was in, they said it was 3000 customers, Some of which are industrial places with VFD motors, boiler controls, you name it. The place I used to work for has a backup diesel generator, but it broke this week coincidentally too.

I also used to work there, and after a regular power blip or outage, a good 10% of the light bulbs had to be replaced. I could only imagine all the burned up motors, ballasts, and bulbs that burned out last night.

Of those 3000 customers, many have fancy homes with all the fancy appliances, and electronics in them. Good week to be an appliance repairman.

I left my modem plugged in for the first 15 minutes of it, and it eventually lost power, and then my wireless house phone started making blips and funny noises.

Great start to Halloween. :)
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Re: Power Brown Outage

Postby Watson on October 15th, 2014, 5:57 pm 

Our power goes off sometimes, but it is all off, not partly off. I did have a similar situation in our home with an old fuse panel and a main knife switch and 60 amp cartridges. One evening the power faded to dim. Turns out one of the 3 cartridges needed replacing and it was all good after that got replaced.
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Re: Power Brown Outage

Postby CanadysPeak on October 21st, 2014, 9:00 am 

zetreque » Wed Oct 15, 2014 1:26 pm wrote:Last night I was sitting downstairs and for roughly 120 seconds the lights flickers and dimmed. It was the start of a bad Halloween movie.... Actually it wasn't, but one of the longest brown outs I have ever experienced. After the lights flickers and appliances went on and off the power stabilized in a really weird situation. The refrigerator had power, but wouldn't run. All of the lights were at half brightness, and some of them wouldn't even turn on.

I went outside and rather than chance burning up some appliances with this strange power, I shut off several breakers in the house, unplugged a few things, and switched my computer to battery, and eventually just went to bed.

I left one light on in my bedroom, so that it would come on when the power was fully restored and wake me up so I could go back outside and turn the breaker on to the refrigerator and furnace.

(It was a monster wind storm last night, and the news currently just talks about many outages all over the northern state, but no details. In any case, it was pretty cool listening to the intense winds all night. One strong gust almost had me stand straight up in bed from a dead sleep as it pounded the windows with tree branches breaking off)

The power was at this "half" power stage for 4 hours.

So what causes this strange power state? It was as if a phase was out, but I know that normal power isn't 3-phase. Would it be something to do with the cycles? 30hz instead of 60hz? Or, is it just not enough voltage coming through? Maybe just one of the lines was knocked out rather than a whole pole?
I didn't feel like testing the power last night with my multi-meter because I was too tired to chance screwing it up by not thinking clearly, and since I recently just purchased new fuses for it.


Normal power in the transmission system is three phase, and that was the likely problem. One of the phases went down, or a ground problem occurred, leading to low voltage in the other phases. Since the voltage in the primary of the distribution transformer was low, the secondary, which goes out to you as single phase, was also low.

It is possible that the pole transformer near your house was damaged, but those usually explode or catch fire so that you get an "all or nothing" power output.

Keep in mind that you only need a drop of less than 20 % of voltage to get half brightness, and that compressors typically shut off for a while after a power dropout till the pressure bleeds off (this effectively shuts down the fridge).
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