Things don't work so well on 70 volts ...

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.

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

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.

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.

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..

focalist:
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..

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.

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.

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

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.

ajofscott:
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.

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... :wink:

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.

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

zHey - We were taught to share here...

[quote author=Nick Gammon link=topic=90278.msg678615#msg678615 date=1328400827]
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.[/quote]

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.

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.

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

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.

@kf2qd

zHey - We were taught to share here...

Sorry, I don't mean to offend here. I mean, our electrical system is integrated with the American electrical system. I simply mean that : if a catastrophic failure in Canada or USA, it may affect a huge area, just like the failure of 2003.

Power failure happen more often in the summer. That when the demand is higher, specialy during a very hot day. All the Air Conditionner are running at the same time.

Having a back-up system is a good idea. But a small wattage unit ( 800 Watts ) is not enough for cooking, fridge, etc. As for light, I use an old fashion oil lamp. It came from the cottage. I use it when a big three fell on ( close to my car ! ) and cut the electrical power line.

I was thinking, if I can wire my place using 12 V system and use led's ? Just like a camping trailler light system. Use leds instead incadesent light bulbs to minimize the current usage. I guess for the cooking, it is a BBQ and it is outside...

You could do that, wire everything for 12V for illumination. Everything else you're going to need higher voltages.

I was thinking of incorporating the code suggested by RuggedCircuits, and make an Arduino "power outage monitor". So, basically as soon as it detects it has lost power it uses that second or two of grace to write that fact to EEPROM (ie. date/time). Then when it reboots it writes another entry. Later on you can interrogate the EEPROM to find all those outages.

Quite useful since our electricity supplier recently wrote to us to say we can claim compensation if the power goes off for more than x minutes. But who would know if it went off for the designated time, say between 1 am and 4 am?

The brown-out is another issue, but you could probably make a little box with a transformer to transform the power down to a safe voltage, rectify it, and then feed the result into an analog input.

No where was this more true then at the refinery I worked at before retirement. They spend literally millions of dollars on dozens of industrial UPS units over the years to power control houses and critical equipment like the process control systems that 'ran' the plants. These were usually large 10-50Kw industrial units, designed and installed per NEC and vendors instructions, and still there was an occasional failures, either human caused or equipment faults. There had to be a rigorous PM (preventive maintenance) performed on these devices that included battery testing and replacement, testing/practicing taking the units out of and into service without interruptions. Many control houses had two UPS units with all the critical electronic equipment loads designed to accept dual AC input feeds from both UPSs. It was quite the engineering effort to get it all correctly designed and installed, but where lost profit opportunity could cost the refinery $1 million a day in some plants it was justified as a cost of doing business using proper risk management analysis.

Lefty

I was working at Digital one afternoon when a maintenance guy was careless.. And ran a pallet jack into a battery rack for a lab, puncturing several and of course shorting all sorts of current from several dozen lead acid batteries...essentially car batteries.

Halon is pretty when it dumps, but you need to get out and not inhale!