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Topic: Things don't work so well on 70 volts ... (Read 1 time) previous topic - next topic

Nick Gammon

Last night we had a strange brown-out where the electricity seemed to go off very briefly and then things behaved very erratically. Like, some lights worked and others didn't. Some computers worked and others wouldn't boot.

A quick check showed that the mains supply had dropped from its normal 220/230 volts to around 70V, and then climbing up and back to around 180 and back to 90.

It appears that some "more modern" lights (eg. LED lights / energy saving) just won't switch on at all, others seemed to work OK, and the old-fashioned globes were very dim. Plus I guess some modern computers are designed to run on 110-230 volts, so getting 70-80V wasn't too bad for them.

I tried to ring the electricity supplier to tell them about the low voltages, but although my call was "important to them" it wasn't important enough to actually answer the phone. The recorded message said that if you know the reason for the fault "stay on the line and inform our technician" but s/he never came online. Then the message said something about "low priority calls will be returned by the operator to the back of the queue". They must have quite a sophisticated system there which can read our minds and know if the call is important or not without actually talking to you.
Please post technical questions on the forum, not by personal message. Thanks!

More info:
http://www.gammon.com.au/electronics

retrolefty

Such 'brown outs" can be very damaging to some electrical equipment. I believe our electrical utility can even be liable for damage caused by such situations, depending on the root cause of the failure.

And yes, calling for wide spread utility failures for things like electricity, natural gas, cable TV, telephone or DSL problems is more then useless as it just seems to make the situation worst then if you didn't try and call at all. Only if your problem is local to your house or nearby street is there a chance of getting through to a real person, and even then it can be pretty painful process. I lost DSL for 8 hours two days ago and spent two hours on the phone talking to machines and real people, they had me performing all kinds of hardware checks and software changes. They finally after 2 hours called the local telephone people via my zip code and said, oh yea they are having problems and service should be restored in about 6 hours, "we are so sorry for the inconvenience". It wasn't the outage that upset me so much as their weak ass troubleshooting process that assumes all problems are due to the customers equipment or software. They wanted me to replace the NIC board in my PC before they figured out they indeed did have a problem with their system. Blah.....

Lefty


Nick Gammon


Such 'brown outs" can be very damaging to some electrical equipment. I believe our electrical utility can even be liable for damage caused by such situations, depending on the root cause of the failure.


I went around tripping circuit breakers for that reason. I didn't want the fridge motor, for example, to burn out. I'm a little surprised they continue to supply power at that level, but perhaps it was out of their control, like a tree over the lines.

It's a pity the recorded message didn't suggest turning of motors (eg. fridge, aircon) for the safety of the home-owners.
Please post technical questions on the forum, not by personal message. Thanks!

More info:
http://www.gammon.com.au/electronics

focalist

#3
Feb 04, 2012, 09:23 pm Last Edit: Feb 04, 2012, 09:31 pm by focalist Reason: 1
Sadly, I'm willing to bet that their failure to say things like that means that if they print something like that, it opens then up to some type of liability.  One thing you can depend on- big business covers it's hiney at ANY cost, particularly if that cost will end up paid for by the customer and not themselves...

Makes you think of building a cutout circuit-- much better to hard fail across the board than what happens to all those poor 'tronics.. testament to some decent engineering, really, in my mind- tolerating power fluctations of that scale is impressive!  

I've seen a 240v AC on two different breakers- breakers that were NEITHER tandem or dedicated to the AC unit, a hundred thousand BTU through wall job..  Also on one of the circuits was all of the exterior (mostly non waterproofed, none GCFI) lighting and sockets.  Guy asked me if I could figure out why he blew out three air conditioners in five years.  Surprised it took that long.  He told me the ONE breaker would trip and the AC would make "funny sounds" until he went and flipped the breaker back.  Gee..
When the testing is complete there will be... cake.

retrolefty


Sadly, I'm willing to bet that their failure to say things like that means that if they print something like that, it opens then up to some type of liability.  One thing you can depend on- big business covers it's hiney at ANY cost, particularly if that cost will end up paid for by the customer and not themselves...

As I said most states have a PUC (public utilities commission) that the utilities must work with on things like rate increases and liability of damage of customers property due to utility caused problems. There was a recent natural gas pipeline explosion that damaged dozens of homes in San Bruno last year that will end up costing the utilities hundreds of millions of dollars and the PUC will make that it comes out of the utilities cost of business not just passed on to the rate payers, at least in theory anyway.

Makes you think of building a cutout circuit-- much better to hard fail across the board than what happens to all those poor 'tronics.. testament to some decent engineering, really, in my mind- tolerating power fluctations of that scale is impressive!

At the refinery I worked at before retiring we had all sorts of protection relays at all the substations on our property to trip power off if over or under voltage or frequency. Power outages are and were expensive but not as expensive if many large industrial motors were to burn out, some were of the tens of thousands of horsepower.  

I've seen a 240v AC on two different breakers- breakers that were NEITHER tandem or dedicated to the AC unit, a hundred thousand BTU through wall job..  Also on one of the circuits was all of the exterior (mostly non waterproofed, none GCFI) lighting and sockets.  Guy asked me if I could figure out why he blew out three air conditioners in five years.  Surprised it took that long.  He told me the ONE breaker would trip and the AC would make "funny sounds" until he went and flipped the breaker back.  Gee..

CrossRoads

Any chance you have busted ground some where? Similar symptons were seen at my inlaws after a lightning strike, turns out their ground wire had been bruned out.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

retrolefty


Any chance you have busted ground some where? Similar symptons were seen at my inlaws after a lightning strike, turns out their ground wire had been bruned out.


Well in theory the ground wire doesn't carry any current in normal operation. The neutral wire is the current carrying wire back to the center-tap of the pole transformer. The ground wire is a ground rod driven close to the service panel and wired to the neutral bus in the service panel. Losing the ground wire is dangerous from a personal protection point of view, but should effect the proper voltage/current flow from the pole transformer to the household loads.

Lefty

ajofscott

Blessfully Nick is in AU and doesn't have a neutral return in the same context as we do here in the USA. About a month after I moved into the house I live in now my Neutral went open(squirrel damage) L1 went to about 35 V and the balance was on L2, making for about 210V, fried several power strips, one of which nearly started the house ablaze, and roasted anything on L2 that used iron core magnetics, along with the electronics on the downstream side. the utility refused to replace the service entry and just patched it back together, just to in turn drop a leg 3 days later.....3 years later still waiting for a service entry replacement.

Nick Gammon


Blessfully Nick is in AU and doesn't have a neutral return in the same context as we do here in the USA.


Things are back to normal now, so I don't think it is anything in-house. We actually have 3-phase power, and I could see from the meter that phase 3 had gone (at least the LED was off) then phase 2, then phase 3 again. So in our case it's possible for some parts of the house to work OK and others not.

We also have residual current devices at the switchboard, so they should trip if power tries to take an unusual path.
Please post technical questions on the forum, not by personal message. Thanks!

More info:
http://www.gammon.com.au/electronics

Techone

Quote
Blessfully Nick is in AU and doesn't have a neutral return in the same context as we do here in the USA.


And Canada...  ;)

I remember in August 2003, a major power failure happen all across the soutern ontario including part of the USA easteern
seaboard <-- I think ?  The power failure cause was located in the state of Ohio. And cause a cascaded failure of the electrical grid and the electrical system in Ontario was inter-connected with the American side also fail. No power for at least 24 hr. Candu nuclear reactor can not just "start" quickly. So Hydro One  and Toronto Hydro have to re-start the system one sector at a time.

Therefore, something goes wrong in the USA, we going down too here in Canada. 

kf2qd



Therefore, something goes wrong in the USA, we going down too here in Canada.   


zHey - We were taught to share here...

KirAsh4


Things are back to normal now, so I don't think it is anything in-house. We actually have 3-phase power, and I could see from the meter that phase 3 had gone (at least the LED was off) then phase 2, then phase 3 again. So in our case it's possible for some parts of the house to work OK and others not.


I was going to say, based on your very first post, I immediately suspected one of your phases having gone down.  My house has three phases feeding power, and thanks to squirrels, crows, and the occasional snow laded branch, we've had a phase go down.  Usually we hear a loud pop when the transformer blows.  With all of my computers on batteries, running off of two main 20Amp lines in the house, I flip both breakers and let the batteries take over and eventually shut things off.  I systematically kill the other stuff as well.  I'll leave circuits with only lightbulbs on them since I can still turn them on, they're just dimmer.  And if they blow, oh well.  Not nearly as expensive as replacing the fridge, or heater, or computers for that matter.

Nick Gammon

I used to have battery backup, but then the battery backup device failed more often than the power did. It's a bit of a fallacy that UPS are really "uninterruptible". They are devices, and they fail like other things.
Please post technical questions on the forum, not by personal message. Thanks!

More info:
http://www.gammon.com.au/electronics

GoForSmoke

I was looking at 800W generators at Harbor Freight today, $139.
But they break down at times, so get two!

Nick Gammon on multitasking Arduinos:
1) http://gammon.com.au/blink
2) http://gammon.com.au/serial
3) http://gammon.com.au/interrupts

KirAsh4

Oh yeah, I recycle my batteries every 2 years, on the dot.  Out with the old.  I tend to take them to electronic swaps and someone will buy them for cheap.  For the cost of replacing the battery packs themselves, plus shipping, it's cheaper to just buy a new unit at the store.

I got bit once when I had a power failure, on a 3 year old unit, and my main file server went down instantly.  I had lost a pretty important (and pricey) project with it.  Since then I said screw it, 2 years replacement it is from now on.

Electronics are electronics, batteries are batteries.  One of them will fail, no matter how "uninterruptible" they claim them to be.  It's a matter of when they will fail.

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