I have an air turbine running in my house, and it slows down when the electric dryer is turned on. Even though the air turbine is on a different circuit from the electric dryer. The same happens when any other appliance in my house that uses a lot of power, goes on.
My electrician came by to check it out, tightened connections in the circuit breaker box, but it didn't help. He's not sure why this is happening. The turbine draws about 3 amps. Any ideas?
tia Laura
I think you need to actually monitor the voltage that's available on each of the circuits, when the dryer switches on and off, and see what's happening. It's possible that you've got excessive voltage drop occurring "upstream" from the breaker panel e.g. in the drop cable from the public-utility pole on the street. A loose connection there, or a wire that has been partially chewed through by squirrels (e.g.) could cause a load-sensitive drop which would be noticeable.
A failing "master" circuit breaker in the breaker box might have the same effect.
Ideally, you would have your electrician monitor the voltage on the various branch circuits, and also the incoming voltage on each phase (e.g. right after the meter), as you add and remove high-current loads. If you find that the voltage available at the meter falls below the normal lower limit, and you're drawing less current than your service drop is supposed to be providing, you should call the electric company and tell 'em they have a problem in their equipment or in the service drop.
The scary situation would be if your turbine fan sped up when the dryer came on, and slowed down when it went off. This would probably indicate an "open neutral" situation, which is quite dangerous - it can result in severe over-voltage on some circuits and can damage motors, burn out lights, or even start fires. If you ever see this happening (or e.g. lights getting *brighter* when you turn on a load), you should call the electric company immediately and report a "high voltage / low voltage problem, open neutral".
--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
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What is the thing you called a turbine, I can make all sorts of guesses, but not really sure? A furnace fan, an attic ventilator fan,????
Can you notice any lights diming or getting brighter when you hear the turbine slow down?
It's like a fan but more powerful, it's part of an airline respirator so it has to push air through many feet of hose. It uses a universal motor, and the speed can be varied by a rheostat.
No, but I use fluorescent lights. I don't think they would do that. The electrician was asking me the same kind of questions.
I tried connecting the turbine to various outlets in my house and the same thing happens - other appliances lower the turbine's speed even if they aren't on the same circuit.
Laura
(...)
Did you see Dave Platt's response? He hit it on the head, IMHO.
--Winston
It might be an idea to try another 'leccy :-) If they can't pick volt drop they should stay chasing walls and running conduit.
At my last house the voltage was fluctuating wildly in half of the circuits in the house. I measured the incoming power at the main breaker and the voltage from one incoming line to neutral fluctuated the same. I called Puget Power and they traced the problem to a failing underground transformer. Eric
la La LA La la I cannnnt hearrr youuuuu!
:)
--Winston
On Thu, 26 Apr 2012 17:38:17 -0700, snipped-for-privacy@radagast.org (Dave Platt) put finger to keyboard and composed:
I would think that high resistance in the breaker would quickly result in its failure. If the voltage drop were around 5V, then at 3A the dissipation in the breaker would be 15W. And that's only taking the motor into account, not the dryer.
- Franc Zabkar
-- Please remove one 'i' from my address when replying by email.
I was thinking that perhaps a loose mains-input connection might cause this, at that point in the setup. There might be enough metal attached to this point on the breaker (e.g. a bus wire in the box) that it could survive for some time... the heat could be conducted away.
I tend to think that a bad mains-drop cable or pole/street transformer is a more likely culprit, though.
--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!
My electrician came over to check it out more thoroughly. He measured voltage at circuit the turbine is on, when I turned the dryer off and on. The voltage only dropped a small amount. I think he said by
2 volts. (earlier on, he measured the current draw, and didn't see a change)But, it noticeably affected the turbine's speed. Earlier, I checked what the turbine speed was doing, with an airflow meter, and when the dryer was turned on, the airflow goes down about 5%. I've noticed the airflow going down much worse than that, at other times.
For some reason, the turbine is very sensitive to a slight change in voltage.
He also checked the voltage before and after the main circuit breaker, and it went down by 4 volts when the dryer goes on, both before and after.
So, he said there's a problem with the utility co's equipment, like maybe a failing transformer, but right now it's a minor problem. I hope the utility co. will fix it.
Maybe the fact that turning on the dryer affects the turbine speed much worse sometimes, means that the problem with the utility co's equipment is erratic.
Laura
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dI hope someone has called the utility co, preferable the electrician so he can tell them what is going on with someewhat more authority than "just" a customer!!
Maybe the dryer is creating a vacuum in the room? Making the turbine load greater or less?
>4 volts is a major drop for a relatively minor load. Typically a clothes dryer is on a 30 amp circuit, but draws somewhat less. An electric range or cental air conditioner is typically on a 50 amp circuit.
Since the voltage drop is occurring at the hot side of the main breaker, it's the electric companies responsibility. It COULD be the lugs on the input to the circuit breaker, it could be in the meter box itself, or it could be somewhere upstream.
PlainBill
Is it a fire hazard? Laura
Good question, let's do some 'back of the envelope' calculations. The tests the electrician made indicates the problem is BEFORE the main circuit breaker. If the entire 4 volt drop occurs at a single point, and the actual dryer load is 25 amps, that means 100 watts is being dissipated. Of course, since the dryer represents only a fraction of the actual maximum load, the power dissipated is much greater. If the power is being dissipated at a single point (a poorly tightened connector), it could POSSIBLY lead to a fire. It is far more likely that the eventual result will be a complete failure of the connector.
Here's my analysis: The voltage drop could be occuring in the wires from the main breaker back to the meter, in the wires from the meter back to the local transformer, or at the connectors in the breaker box, meter housing, or local transformer. If it's occurring in the wires, it's due to physical damage; those wires should be rated for at least 150 amps. Barring physical damage to the wires, the problem is at one of the connectors.
It's unlikely the problem is occurring at the connectors on the main breaker, think of how much heat is given off by a 100 watt light bulb. A self-aware electrician should have noticed the heat. It could be in the power meter housing, but my suspect would be at the local transformer. And that is big enough, and runs hot enough that an extra 100 watts isn't noticeable.
PlainBill
The utility co. came out, a crew replaced some wire that they said was very old. After changing the wire, they checked line voltage when I turned the microwave off and on. The voltage went down from 243 something to 240.8 when the microwave was on, it uses a KW. But, the utility co. guy said a 2-volt drop when the microwave goes on, isn't a problem! He said, you get 240 volts and that's what we promise. My dryer is broken, the on-switch died, so I couldn't test voltage change with the dryer on. So, IS there a problem with the wiring upstream of the meter? I tried plugging the air turbine into various circuits. On many of those circuits, the turbine would slow down when the microwave went on. Right now I have it plugged into a circuit where the microwave doesn't slow the turbine. The utility guy said they'd put a recording voltmeter on the meter. Which seems sensible. The voltage did drop to 238 volts previously when the dryer went on. So that's below 240. I hate it when this sort of confusing stuff happens. I don't know who is right. Laura
Understand that the home electrical system is fed by a center tapped secondary of a step down transformer. The center tap is neutral, and is tied to earth ground at your breaker box. The voltage from either end of the secondary to the center tap is nominally 120 volts (it may drop under load). The voltage from one end of the secondary to the other is 240 volts. The typical outlet is wired from the center tap to one of the ends, the dryer is wired across both ends.
It would be interesting to know if the voltage from the center to each side drops the same amount when the dryer is running.
One relatively simple test you can do. You have identified at least one circuit where the turbine is not affected by the microwave. It would be interesting to know if that circuit is affected by the dryer.
PlainBill
When my oven comes on my kitchen light dims for about 1 second so does that mean I have to call 9-1-1 now? You stupid bitch.
The utility co. took down their recording voltmeter. It was on the weatherhead, on my roof where the power line is attached.
I talked to an engineer at the utility co. today, and he said everything is fine with my voltage. He said it's between 120 and 124 volts usually, he saw one time it went down to 115 volts.
The only thing he noticed was that the load is somewhat unbalanced, like 25 amps on one leg and 10 amps on the other, usually.
Could an unbalanced load cause voltage fluctuations?
One day when I was doing my laundry and the heat pump may have been working hard, he said the load went up to 55 amps. I don't know if this could cause flaky voltage inside my house, it's 100-amp service.
I might borrow or buy a voltmeter, and see whether voltage at the outlet correlates with the drastic fluctuations in airflow that I've noticed.
I doubt it's the fault of the motor volume control, because the airflow goes up rather predictably at night.
And like I said, when I use the electric dryer, the airflow predictably goes down, sometimes a lot.
Maybe there's something other than just voltage that might be affecting the turbine speed. Some other power quality issue, perhaps.
Laura
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