An earlier thread referenced a concern about "low voltage" burning out pumps, furnace motors, etc. A very legitimate concern, and one I have never seen mentioned before. I have placed a few of those "transient spike" inhibiters on some of my ac outlets, including the basement furnace to protect against _another_ blower motor burnout, but had not considered potential low voltage generating problems simply because, to my knowledge, none have been encountered here! But yes, they are possible, or even proabable. So, outside of disconnecting circuits, how does one prepare for these?

-- A. Hambley (a.hambley@usa.net), May 09, 1999

Answers

The only way to handle low voltage situations is either an UPS (Uninterruptable Power Source) which will take the incoming power whatever the voltage, turn it to DC and then produce a synthisized AC voltage, or to use an isolation transformer. Neither is very affordable on a whole-house of business basis. UPS's are intended more for computer and electronics applications.

Isolation transformers can handle large loads, such as refrigeration systems, furnaces and so on that need protection from low-voltage. But these are something seen more in industrial applications or large commercial facilities, rather than in a home power filtration use.

WW

-- Wildweasel (vtmldm@epix.net), May 09, 1999.

WW, An isolation transformer especialy the fixed kind will not work. They are operating after the same prinzipal as garbage in --> garbage out.

Low voltage into an isolation transformer will result in low voltage out unless you have a step up transformer. Many surplus places have small 20-30 amp variable auto transformers for sale that are adjustable from 110V in / 0 to 140v out. Problem will be that you have to adjust it constantly. The better solution would be a bank of batteries and multiple inverters driving one application at a time. I have set mine up to run the sump pump with one and the heater blower with the other one. Everything else will be disconnected at the critical moment. As soon as the voltage on the main input to the house is lower then 100v for > then 5 seconds the house will be disconnected using a 200Amp interuptor. The sump pump batterie is charged over a solar array and the blower batterie is charged over solar and or net-charger that is still connected to the incoming mains and has a working input voltage from 60-280V.One batterie is soley for 12v emergenzy lighting and is charged with a small 20w solar pannel. Look at places like a local hamfest or Surplus Sale of Nebraska for variable xfmrs.

-- Rickjohn (rickjohn1@yahoo.com), May 09, 1999.

I have been wondering about too low/too high voltage too. Can someone who has expertise (not just an opinion) in such matters please advise? What shuld we do to protect our refirgerator, computer, water pumps, etc. ? I have heard that lightbulbs are not harmed by up/down voltage. Is this true?

-- Shivani Arjuna (odnsmall@aol.com), May 09, 1999.

Surge Protectors, as sold in hardware and computer stores, are commonly used to minimize voltage spikes, but persistent low voltage - if delivered by your power co. - are a whole new ballgame. Lights dimming are a common indicator. Lightbulbs are cheap, compared to on-line electronics and ac motors.

-- A. Hambley (a.hambley@usa.net), May 09, 1999.

I asked this question on euy2k a while ago. Here are the responses.

greenspun.com : LUSENET : Electric Utilities and Y2K : One Thread

On an earlier thread, Greg Holmberg asked if he could protect his home devices from brownouts. I, too , would like to know. Is there some device that can be used? As there is no way of knowing when these brownouts occur, but understanding the damage they can cause, would it not be better to have either no power or full power? What damage would this situation do to the manufacturing industry? Telecommunications? Hospitals? I am beginning to think that we will be dealing with a lot of these brownouts, and I just do not understand enough about the problems they could bring. A general explanation would be helpful and if this has been covered please refer me to the appropriate thread. Thanks all.

-- Mike Lang (webflier@erols.com), March 07, 1999

Answers

Fancy meeting you here Mike! I guess you could use a UPS, like the ones used on a PC, for other sensative devices, at least for short term protection. I hear some power cos. do offer "full house" protection. Just my $.02 since many others here are far more qualified to answer this question. <:)=

-- Sysman (y2kboard@yahoo.com), March 08, 1999.

For very limited applications, a "line-conditioner" with step-up/step- down solenoids may help. I have an 1800W TrippLite, which is essentially a BIG transformer with a variety of windings. The unit monitors incoming voltage, and adjusts (using solenoids) which windings are used so that output voltage is held steady (about 1/2 second response-time).

Cost a few hundred bucks. Does nothing for blackouts - just a *great* surge-suppressor and brown-out aid. Bought it for my PC years ago.

-- Anonymous99 (Anonymous99@anonymous.com), March 08, 1999.

there is a 120/240 volt surge suppressor available at your home improvement stores for around $40-50 that you hook up at the breaker panel. commercial applications have saved on power usage by keeping compressors running at a lower temperature by removing spikes. as a licensed electrician, i used to sell & install these back in the 70's and recently bought one for my home.

-- bryan skillestad (cannonrealty@juno.com), March 08, 1999.

The problem is that the utility industry and the feds are so busy telling everyone that "all will be fine, everthing is on track" that people who need to be buying these devices you have mentioned are not buying them! Disruptions are bound to occurr and business suffer burnt out equipment due to this oversight.

-- Steve Watson (swatson1@gte.net), March 10, 1999.

Link

I am still curious as to the effect on businesses, hospitals etc.

-- Mike Lang (webflier@erols.com), May 09, 1999.

Also see this thread about the danger of frequency or voltage variations to electronics...

http://www.greenspun.com/bboard/q-and-a-fetch-msg.tcl?msg_id=000bFR

"Electricity in New Mexico -- Safeguard your electronics?"

-- Kevin (mixesmusic@worldnet.att.net), May 09, 1999.

Hambley:

A line conditioner will do it. You will need an electrician unless you are pretty good with electrical work.

There are other motors in your house too. (i.e.) refrigerator, washer/dryer, freezer, burner and air handler motors.

Do a complete inventory and get the amperage of of each one + voltage. Your electrician can transfer these circuits to a separate subpanel that would be fed through a line conditioner. THis will stabilize the voltage through a range as defined by the manufacturer.

One source is Grainger (Grainger.com) I located a possible series of conditioners on page 405 of Cat #389 and parts nos. 5B591 thru 5B599 . They range from 250va to 2000va (watts). This should do it for you.

However the are not cheap. $505 to $1278 for just the conditioner.

Best to you on this, and no, I don't work for Grainger LOL

Bob Pilcher Pilcher Electric Lic #11234 NJ

-- Bob P (rpilc99206@aol.com), May 09, 1999.

Larger UPS systems can be obtained from solar and wind power companies. You buy the batteries and inverter/charger separately. Inverters normally used are made by Trace, Statpower, Heart and others, and range from 1500 W to around 5000 W. Some of them automatically switch to battery power when line power gets too low, just like a computer UPS.

-- Dean -- from (almost) Duh Moines (dtmiller@nevia.net), May 09, 1999.

I asked the question about how to protect electric motors from "brownout" (or low voltage) some time ago on another list. An electrical engineer told me to fuse the motor separately with a fuse or breaker that would barely carry the load when running, using the slow-blow type of breaker or fuse. I haven't done it yet, but intend to protect my refrigerator, freezer(s), and furnace fan with such breakers.

My understanding was to check the running amps with an amp-probe and protect it with a breaker just a couple of amps larger. My refrigerator draws 4.8 amps running, so I will use a 6 amp fuse (yes, there is such a thing, but probably will have to be special ordered).

Gerald

-- Gerald R. Cox (grcox@internetwork.net), May 09, 1999.

Sorry to just drop that low voltage thread and run. To answer a question, yes it can happen, and yes it will burn up your motors. Back in the 50's and 60's the power was not so good. There were several times a month we would experience a brown out. You never saw people move so quick, mom to the frig, dad to the furnace, me to the B&W tv. We always made it to the frig and tv intime, but the furnace had several motors replaced/ rebuilt. The motors were great to fry eggs on though! :)

-- FLAME AWAY (BLehman202@aol.com), May 09, 1999.

There are transformers which are configured to take input voltages from 90 to 150 volts AC and yeild 120 vac. They have no sophisticated components, no moving parts. I think they are called 'magneto-dynamic' or something like that. They self adjust. Can get them in surplus shops. With this type the voltage could swing all over the map in a few seconds and the output will remain 120 vac. When the voltage is low it draws more current to compensate. When the voltage is high it draws less.

-- David (C.D@I.N), May 09, 1999.

David,

Never heard of magneto-dynamic transformers. Perhaps ferro-resonant? They operate like a tuned radio circuit, passing only 60 Hz AC, and by operating near core saturation, can provide a small amount of "built-in" voltage regulation.

-- Elbow Grease (Elbow_Grease@AutoShop.com), May 09, 1999.

only finished some of my physics work, but wouldn't you be able to use several capacitors in series to act like a step-up transformer?

-- sarah (qubr@aol.com), May 09, 1999.

Elbow - no not like that. Its a transformer set up with internal feedbacks. Its all electro-magnetic and 'equalizes' volateg variations somehow. Quite a rig actually. And has very broad input with very narrow output. Very simple, I just don't understand it and can't explain it %-)

-- David (C.D@I.N), May 10, 1999.