UPS overload question

My father is afraid of his treadmill suddenly stopping while he's walking due to a power outage. I figured that a ups backup could give him some time to step off before it stopped. But I figured that the least expensive one with the lowest power rating would work, since I assumed that the power rating was only to give you an estimate of how long the unit will power an item.

Since most of the ups units offer several minutes for a low load, I figured that it would give a more than adequate 10 to 20 seconds at the higher load of a treadmill.

Will it work or will something trip inside the unit if the load is greater than the rating?

Thanks, Jeff

Reply to
straightnut
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Entirely wrong, I'm afraid. If the treadmill takes significantly more power than the UPS is designed to supply, the UPS will simply not function, at all. Not even for a second. It is designed to sense an overload condition and trip out under such conditions..

Worse still - the motor in the treadmill will typically draw extra power during starting, over and above its rated power in use. A UPS must be rated with that starting power in mind as well as the running power.

Reply to
Palindrome

How often does the power go out, and just how fast is he chugging along on that thing?

If this is really something keeping folks up at night, simply fire up the treadmill at the speed he uses it, unplug it, and see what happens. If the treadmill is going fast, it should take a few seconds to come to a stop, and if it's going real slow, you'll barely notice.

CS

Reply to
CS

Thanks Sue. Exactly what I needed to know. The UPS is going back. Jeff

Reply to
straightnut

He's in his late 70's and he loses his balance when the wind blows. He's also very fearful. I think he had a fall once on it or he slipped. Just thought it might be a good gift. Should have gotten him socks. Thanks for the help. Jeff

Reply to
straightnut

| My father is afraid of his treadmill suddenly stopping while he's | walking due to a power outage. I figured that a ups backup could give | him some time to step off before it stopped. But I figured that the | least expensive one with the lowest power rating would work, since I | assumed that the power rating was only to give you an estimate of how | long the unit will power an item. | | Since most of the ups units offer several minutes for a low load, I | figured that it would give a more than adequate 10 to 20 seconds at | the higher load of a treadmill. | | Will it work or will something trip inside the unit if the load is | greater than the rating?

DC to AC power inversion tends to have very little overload headroom above the nominal maximum operating range. Generators have more, but not a lot more. Your utility mains electric supply has a lot more overload capacity. They have some "big honk'n generators".

Even if the UPS does not trip when running on working mains supply, it may well just quit when overloaded in DC operating mode when the mains goes out.

The only (IMHO) safe way to run a motor on a UPS is to get a UPS rated for operation at the motor's LRA (lock rotor amps). And that would be a rather large UPS.

FYI, I have found that running the circuitry of a house on a UPS, even a large one rated for a whole circuit capacity, could well be unsafe because it is unable to deliver the current (but at some rating levels would not trip itself off, either) to magnetically trip building circuit breakers in the event of a short circuit. Even a small generator can be unsafe for just such a reason, or even a medium generator for a whole house (does it have the ability to deliver the current needed to trip the main breaker in the event of a fault that needs to trip the main?).

Reply to
phil-news-nospam

He's in his late 70's and he loses his balance when the wind blows. He's also very fearful. I think he had a fall once on it or he slipped. Just thought it might be a good gift. Should have gotten him socks. Thanks for the help. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

He should use the hand rails. If it didn't come with them, either build some or have somebody else do it...it shouldn't be too hard to rig something up for him to hold on to. In my opinion, those will be safer than a UPS anyway, with extra cords and boxes to trip over.

I've seen the shows where the guy on the treadmill goes flying backward or forward due to a moment's inattention to foot placement, but unless your an Olympic athelete running for your life, it's unlikely you'll go anywhere.

I do understand the fear of falling on these things. I was using mine to speed my recovery from a quite nasty injury, and I'm not too coordinated in the first place (hence the injury), so I made liberal use of the hand rails and went real slow. To be honest, I got better results from working out in the pool. If you fall there, you just get wetter.

CS

Reply to
CS

Okay thanks everyone. Jeff

Reply to
straightnut

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