A sad day in the shop, dead motor

B

Burdick101

New member
Well....

It took well over a year for me to put it together after trying in vain to build my first cyclone, giving up, and buying a Clearvue (Something I'll never regret). My baby ran fine for a few months and then out of the blue, while working new hardwood floors in my house, My cyclone just wouldn't start. The motor would turn on and fight the spin up for 10 sec and then the breaker would trip... it was the weirdest thing.

A little background.... I'm using a Harbor freight motor and a 20Amp circuit. Don't give me too hard a time, I was trying to save cash. Anyway, long, long story short, the motor breathed it's last breath after I tried uping the breaker to a 30amp to give it a bit more juice. I think now the motor is completely dead.

So my questions are these:
1) I have a Sheldon Engineering impeller with a 5/8" hub because the HF motor had a 5/8" shaft. I would like to re-use the impeller and not have to build a new blower housing to support a 15" impeller. Anyone know if this QD bushing is a standard? Sheldon referenced a QD bushing on their site, as well as the Clearvue folks.

2) Given that I am indeed using a 14" impeller, is that a bad thing for the Clearvue cyclone? Am I causing undue stress on the motor? I admit I am suprised to read that closing all the blast gates reduces the amperage on the motor, i would have thought the other way around to be true, but it's starting to make sense now.

Thanks for all your help in getting me back up and running.
Nick
 
Sorry you're having motor problems. It is possible that the load is too big for the HF motor, or it could be that you have burned out one or both of the start capacitors. Worth taking the 2 little "bumps" off and looking to see if there is black ooze coming from one or both. (BE SURE TO DISCONNECT POWER FIRST!!!) If so, they are cheap, about 5 bucks each. Worth a shot. It might buy you some more time before you HAVE to change the motor out. There should be several motors that will work with the Sheldon impeller. I bet the Leeson 5 hp that comes with the full CV unit would work. Seems like the first units came with the Sheldon unit, but I may be wrong. I know Bill Pentz had them as a recommended impeller on his site at one time. Good luck! Jim.
 
Leeson Motor

Leeson Motor

Nick,

Sorry to learn of your motor woes. Jim's right, check the caps first but don't hold your breath.

As to your question with respect to the Leeson, and I assume but don't know for sure if the shaft will fit, the way these things work is the motor will attempt to spin at a constant RPM. Thus if the amount of air being moved by the blower is less, it'll take less juice to turn at that RPM. While I don't know the particulars of Sheldon's blower, I'd hazard that at 14", it doesn't move quite as much air as Matt's. Thus there'll be less power demand, i.e., the motor won't be working "as hard".

Said another way: If it takes, say, 3 HP to move the air with the Shelton blower, it'll still take that same 3 HP with the Leeson. And the latter is rated at 5 HP, so....

Would ensure at least #10 wires and a 30 amp breaker, though.

Regards,

DWD
 
Nick,

Sheldon's should stock other sizes of bushings. And yes they are standard to a point i guess. We use the style JA and we may have one of the other styles left over but we don't stock them. McMasterCarr has them although the bore sizes on the page don't seem to be right....Search for QD bushings. We also have motors in stock if you decide you want a leeson. Call us after you find a motor and i'll see if I have a bushing.

Matt
 
As I work to get my system back up and running, I have a few questions for you folks:

How important is a TEFAC motor? I think one of the problems, though I have yet to confirm by looking at the dead motor, is that the harbor freight motor was closed off on the shaft end because of how I had to mount it to the blower assembly. Would this have worked to burn it out? Would overheating burn out the start Caps?

I never had the thermal reset trip that I could tell, but when i was testing before it died, it did seem to get quite warm. How warm is normal?

I'm considering buying a LEESON motor, but one that fits my existing installation with a 5/8 arbor. Anyone recommend against it? There is one on EBAY now:

http://item.express.ebay.com/NEW-5-...0QQitemZ230226345020QQihZ013QQcmdZExpressItem

Thanks for all your help
 
...Anyway, long, long story short, the motor breathed it's last breath after I tried uping the breaker to a 30amp to give it a bit more juice. I think now the motor is completely dead.
Click to expand...

Yeah, I know this is a long-dead thread, but I just ordered my CV so I'm going through all the old posts to gleen information. If Nick is still around, I hope he sees this.

NONE of you scolded Nick for "giving more juice" to his motor by upping the breaker size? :confused: This is dangerous! :eek: The only thing upping the breaker size does when electrical equipment has failed is to give more time for a fire to break out.

To be clear: a breaker doesn't regulate current, it monitors current. Even if you originally undersized your breaker...if your motor's current draw didn't trip the breaker and then after months of service did start tripping the breaker , now is NOT the time to properly size the breaker.
 
K9-mal, I am not an electrician, but I was always told that the breaker was sized to protect the wiring, not the load.
 
The breaker is there to protect the wiring, the load, and most importantly you and your property.

Both the breaker AND the wire have to be sized per the load. Both a simple light bulb and a motor will have a rated current draw and will indeed draw that current regardless of the wire or breaker sizing. Wire that is too small for the rated current draw will at best damage the load, at worst will overheat and cause fires. Breakers that are too small for the rated current draw will simply trip. Increasing the size of either doesn't MAKE more current flow or provide more power, it simply ALLOWS more to go through.

So, if you have a load rated at 20 amps and you put a 60 amp breaker on the circuit, you'd allow a 39 amp malfunction to go unnoticed until a fire broke out.
 
Last edited:
K9-mal is dead-on! Nick's choice to change his breaker to 30 amps should have only been done if he had at least #10 wire in the wall and it was a poor move anyhow. As all of us know, a Leeson 5HP motor used with the ClearVue needs a 30 amp breaker because the motor is FLA (Full Load Amps) rated at about 21.5 amps, necessitating #10 for a moderate length run. If he had his HF motor on a 20 amp circuit that was wired with #12 wire and he changed the breaker to 30 amps, then he ran a high risk of causing a fire since he was exceeding the ampacity of the wiring when he connected his damaged motor, notwithstanding its FLA. As he found out, his motor was already cooked and attempting to "force-feed" more amps wasn't a good choice anyhow as it sealed the motor's fate. In re-reading his posts here, it sounds like his motor may have been undersized for the 14" impeller and was running under excess load and overheated due to poor air circulation and that overloaded it.

Nick mentioned upgrading to a 5/8" shaft Leeson -- one would hope that his wiring and circuit breaker would support the FLA of his new motor. I'm not an electrician, but I've read enough about wiring and connected loads to know what's right and what's wrong. One always needs to have wiring sized to meet the intended load and the proper breaker to protect that wiring during an overload.
 
A sad day ...

A sad day ...

It really is worthwhile to go to your local library and read section 430 of the NEC. You will find a number of surprises with respect to motor care and feeding. For example, circuit breakers do not protect the wiring from motor overloads. They do protect it from shorts and ground faults. And this is just one of the surprises you are in for. Most libraries keep the latest NEC as a reference book but they will let you take an older version out. The basics haven't changed that much.
bababrown
 
Transition from 10-3 to Motor

Transition from 10-3 to Motor

If I remember correctly, the main reason for the wire guage being a little oversize is to allow most of the voltage drop to occur across the motor rather than a substantial part of it across the wiring.

However, for much shorter runs, say 24" or so, and internally inside the motor, 10 guage would be overkill. It appears the the motor leads themselves are 14 guage stranded. Rather than try and force the ridgid 10 guage solid into a small junction box, I terminated it at the end of the conduit run, (at the relay box), about 24" length from the motor, and ran 12 guage stranded from there in to the motor box. I haven't powered it up yet, but I would guess to see less than 250 millivolts across that 24" length. I'll meter it before it runs too long with no ducting attached.

Anyone know what the minimum full load voltage (240v supply) should be across the motor?
 
Transition from 10-3 to motor

Transition from 10-3 to motor

John,
I practiced electrical engineering for 35 years and I thought I new how to wire motors until I finally took time to read section 430 of the NEC. 10-3 Romex wire does not meet code for a 5HP motor and high temperature #10 wire in conduit meets it only if all terminals it connects to are rated for at least 75 C. Reducing it to #12 is worse. Taps are disallowed in almost all cases. I strongly encourage all to take the time to read section 430 (available at most good libraries) and the sections on wire, especially on Romex or type NM.
bababrown
 
John Lloyd said:
If I remember correctly, the main reason for the wire guage being a little oversize is to allow most of the voltage drop to occur across the motor rather than a substantial part of it across the wiring.

However, for much shorter runs, say 24" or so, and internally inside the motor, 10 guage would be overkill. It appears the the motor leads themselves are 14 guage stranded. Rather than try and force the ridgid 10 guage solid into a small junction box, I terminated it at the end of the conduit run, (at the relay box), about 24" length from the motor, and ran 12 guage stranded from there in to the motor box. I haven't powered it up yet, but I would guess to see less than 250 millivolts across that 24" length. I'll meter it before it runs too long with no ducting attached.

Anyone know what the minimum full load voltage (240v supply) should be across the motor?
Click to expand...

I think you may be over simplifying the situation. What is done inside the motor cannot be applies to wiring outside the motor. There are many factors that are considered. I have the 5HP Leeson motor. None of the online wiring calculators I have found give a result less than 10 gauge for this application.

Don
 
bababrown said:
John,
I practiced electrical engineering for 35 years and I thought I new how to wire motors until I finally took time to read section 430 of the NEC. 10-3 Romex wire does not meet code for a 5HP motor and high temperature #10 wire in conduit meets it only if all terminals it connects to are rated for at least 75 C. Reducing it to #12 is worse. Taps are disallowed in almost all cases. I strongly encourage all to take the time to read section 430 (available at most good libraries) and the sections on wire, especially on Romex or type NM.
bababrown
Click to expand...

First, I appreciate the advice, and I am not suggesting anyone else does as I do, nor am I trying to convince anyone I am “right” but I don’t feel it’s necessary to run Hi-temp individual conductors in conduit for this motor.

My voltage here, very close to a substation, runs 246-247 most of the time. We don’t have mandatory code inspection for anything here, and many people built their own homes. I know of no one who runs conduit for instance in a home or garage.

I did read article 430 of the NEC (as much as I could find on the internet) and while not an engineer, ( I did carry an electrical card for 7 years while working in surface mines) I’m sorry, but a lot of this is overkill. Admittedly better than under, but still I have to wonder how much is designed to promote the financial well being of the industry itself. If I could live in a perfect world, I’m quite certain I couldn’t afford it. Reasonable risk is a factor we have to consider in every facit of our lives, and you can find ( I did) arguments to support almost any position.

This is a practical example I have in my shop. I have a “7” horse, compressor duty AO Smith on a 2 stage air compressor. The motor and pump are continuous duty and the pump has a 100,000 hour life cycle. The break-in is to allow it to run 4 hours wide open. The motor is not 7 horse, but draws 17.9 amp with taps open, and 18.5 with it kicks off at 180psi. It’s wired with 12 guage extension cord material, 10 feet long. The max drop across the motor right before it kicks off is 1 volt difference than the open circuit voltage in my load center (147 at the center and 146 at the motor. The motor is rated at 40 degrees Celsius rise, and I have had it run continuously at least 2 full weekends, 48 hours or more, with the pressure around 50-60 psi (blown regulator diaphragm one time, bad quick connect the other), and I could hold my hand on the motor (not suggesting it wasn’t hot, but did not burn me) and felt no heat in the cord at all. So P=IE, 18.5 x 1 volt drop on the 10’ x 2 12 guage stranded extension cord is 18 watts total across the line. The 20 amp breaker will keep the line safe in case of a motor stall, or short, and it and the thermal overload on the motor should keep it safe. Since it’s never failed to start, or stalled, I can’t say for certain but I’m very comfortable with the power dissipation in the 10 feet of line cord.

I guess the point is, that if the Leeson does draw no more than 21 – 22 amps at (my) 246 volts, and I meter the drop across the motor, and it shows I am dissipating no more than 40 to 50 watts or so in the 40 feet of 10-3 romax, and/or have a voltage drop of 2 volts or less difference between load center and the motor at full load, and I have it on a 25 amp breaker, I’m going to be happy and feel quite safe. All connections are soldered.

I can’t see that I am stressing any part of the system.

Thanks
 
Don01 said:
I think you may be over simplifying the situation. What is done inside the motor cannot be applies to wiring outside the motor. There are many factors that are considered. I have the 5HP Leeson motor. None of the online wiring calculators I have found give a result less than 10 gauge for this application.

Don
Click to expand...

Why not? In you take into account power dissipation, voltage drop, breaker size and conductor length.

Try plugging a total length of 4 feet into the calculators. I did and (darn!, forgot exact numbers, now I have to go back and check again, old age catching up I guess), but it was more than adequate (14 guage) for that length (24") and the load current.

Consider the size of a fuse conductor compared to the working conductor. and you'll find it's several orders of magnitude smaller (in area) than the recommended conductor, and it's designed to fail only in abnormal circumstances, but it's very short.
 
John Lloyd said:
Why not? In you take into account power dissipation, voltage drop, breaker size and conductor length.

Try plugging a total length of 4 feet into the calculators. I did and (darn!, forgot exact numbers, now I have to go back and check again, old age catching up I guess), but it was more than adequate (14 guage) for that length (24") and the load current.

Consider the size of a fuse conductor compared to the working conductor. and you'll find it's several orders of magnitude smaller (in area) than the recommended conductor, and it's designed to fail only in abnormal circumstances, but it's very short.
Click to expand...


You may well be correct in your assumptions and have no issue with the risks. One of the reasons for over rating conductors is they are usually hidden inside a wall where the real potential of a fire from over heating does exist.
Many of us suck max amps through 16 ga. extension cords with no problem.

My preference is to stay on the side of current regulations should something happen that requires me to have to phone my insurance company to replace my workshop and contents.
Rather than a conspiracy to put more money in the hands of manufacturers, I suggest that these regulations and standards are in place to try and protect us and those around us from ourselves.
Hope it works out for you.

Don
 
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