Starting around one thirty this afternoon (Jan 9,2000) we started seeing power fluctionation. Very unusual here. If we have power (we are rural and will lose power all the time in the winter storms), it is always clean. For the third time in a week voltage fluctuations are occurring. We had power drop down to threshold levels and appliances (like tv, grinder - I was out welding at the time) were turning off. So I checked with fluke ampmeter and found that we had voltage drop to 87 and rise as high as 130. Not good.

Lasted for about two hours. Now at 120 and steady.

Somewhat un-nerving. Not like going dark.

-- pliney the younger (pliney@puget.sound), January 09, 2000

Answers

Thanks for the post, pliney; and maybe compare my thread of yesterday: "FWIW: Extreme Fluctuations in Streamflow ..." Add this post to the slooooooooowly growing list of reports of unprecedented (but otherwise unremarkable) spotty and dirty power. I would like to see a resurrection of a recent thread, Power Spikes and Surges, accidentally deleted by sysops.

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-- (squirrel@huntr.com), January 09, 2000.

The power is pretty dirty up here in the north sound area as well. I don't have the equipment to test, but the lights flicker daily since the first.

-- (formerly@nowhere.Zzz), January 09, 2000.

I installed a surge protecter on my main panel. Cost $44.00 at my local discount lumber/hardware store.

There is no inexpensive protetion for low voltage, but I got a line voltage moniter for $20.00 at an RV sccessories store. It plugs into a recepticle and has an analog needle.

-- John Littmann (littmannj@aol.com), January 09, 2000.

I used to run a recording studio near a substation which also serves a large hosiery mill. I could put the 3 phase on an oscilliscope and see how bad it was. I had many disputes with the power company which came to naught.

In the process, I learned that here in NC the power company is required to supply 120 volts plus or minus 7%..... that is, 7% on either the up or down side, or a 14% range in all. Needless to say my recording equipment needed lower tolerances than that, but I had no way to bother the power company over it because of the 7% rule.

Whenever the hosiery mill kicked in its big motors, there would be an 1100 volt surge that sometimes lasted 2 seconds. I also put a counter on the frequency and got oscillations between 40 something and 100 Hz.

The lower end of the voltage problem is more damaging to equipment than the 130 volts is. 87 volts might not make the device actually work, but will indeed dissipate as heat and damage things, especially big expensive germanium transistors in power supply regulating circuits.

-- Forrest Covington (theforrest@mindspring.com), January 09, 2000.

A typical surge protector will not protect you from sustained overvoltage. They are designed with MOV elements (metal oxide varistor) that can absorb very high voltage/very low current/very short duration spikes. In other words, the kind of transients you'll get from brush noise from motors and induced (distant) lightning discharges. They *cannot* sink a sustained overvoltage at full current.

A full-time (constant duty) UPS or a decent sized CVT (constant voltage transformer) will handle sustained moderate over- and under- voltage.

-- Ron Schwarz (rs@clubvb.com.delete.this), January 09, 2000.

Hi Ron,

A whole house surge protector, mentioned by John L., could protect against a sustained over-voltage by tripping the main breaker. The type I have will clamp at 440 volts (on a 240 volt circuit) and draw enough current to trip my 200 amp breaker. Of course, it also protects against spikes.

-- Dean -- from (almost) Duh Moyn (dtmiller@midiowa.net), January 09, 2000.

Any chance that the major wind storm we were having contributed to this problem? I lost power for about 10 seconds.

-- Phread (lurking@y2k.com), January 10, 2000.

Herbach and Rademan (800-848-8001) sells a nice lil' magneto-dynamic (passive) power conditioner (2 KVA @ 120 VAC) for $69.95.

Cat# TM99PWS3289

"Regulation range +7% to -23% of nominal Output +/- 5%, 1 to 2 cycles adjustments. Continuous duty....70# s/w."

Could be just waht the doctor ordered, folks.

-- ..- (dit@dot.dash), January 10, 2000.