how to check the windings on a three phase motor?

[nwcove]

Re: how to check the windings on a three phase motor?

heres a couple of pics of the tag, 200v, 3 phase

 

[bruceb58]

Re: how to check the windings on a three phase motor?

Like Bigdee said, just measure the ohms across the red, black and yellow in all combinations. They should all be equal.

 

[nwcove]

Re: how to check the windings on a three phase motor?

thanks guys, it all checks out good. windings are equal, no shorts to ground. now just need to find the person that can use a 3ph pump! lol

 

[bruceb58]

Re: how to check the windings on a three phase motor?

thanks guys, it all checks out good. windings are equal, no shorts to ground. now just need to find the person that can use a 3ph pump! lol

That is going to be the hardest part!

Sorry for doubting you about 3 phase!

 

[alldodge]

Re: how to check the windings on a three phase motor?

thanks guys, it all checks out good. windings are equal, no shorts to ground. now just need to find the person that can use a 3ph pump! lol

Agree with Bruce, only ones that would use 3ph would be a large business and they probably wouldn't want a used pump. I wish you the best of luck and if I hear of anything I'll keep the link to advise.

 

[rbh]

Re: how to check the windings on a three phase motor?

thanks guys, it all checks out good. windings are equal, no shorts to ground. now just need to find the person that can use a 3ph pump! lol

Farmers or smaller produce producers, orchardists maybe could use a 3gpm pump.

 

[nwcove]

Re: how to check the windings on a three phase motor?

That is going to be the hardest part!

Sorry for doubting you about 3 phase!

no problem on anyone doubting the 3 phase ! its not a common pump, and as alldodge mentioned its meant for schools/apartment bdlgs, etc. but on the plus side, the liquid end will accept a 1 hp single phase motor. at least i can try to sell it now , knowing that its a good unit.

 

[bigdee]

Re: how to check the windings on a three phase motor?

no problem on anyone doubting the 3 phase ! its not a common pump, and as alldodge mentioned its meant for schools/apartment bdlgs, etc. but on the plus side, the liquid end will accept a 1 hp single phase motor. at least i can try to sell it now , knowing that its a good unit.

So it is a 1hp motor? What is the diameter of the pump/motor? What is the outlet size? In the hands of the right guy that thing can be run on single phase power. I have installed many 3 ph motors on residential single phase. With a 1hp inverter drive and a pressure transducer you can program that pump to hold a constant 50 lbs or whatever without using a on/off pressure switch. And all for around $200. 3ph motors are much more efficient and more reliable. Actually there is no such thing as a single phase motor...they are tricked ( by windings or capacitors)to be split-phased or poly phased.

 

[nwcove]

Re: how to check the windings on a three phase motor?

its a 4 " pump, the discharge nipple is 1 ".

 

[hrdwrkingacguy]

Re: how to check the windings on a three phase motor?

Three phase is reasonably common here in older residential houses...There is a point in motor HP where switching to three phase makes sense a 1/2hp 3p or 1/2 1p is a toss up which is better, but when you get north of 3hp its way more efficient to have 3p power...




6/9 wire are dual/tri voltage offer a lot of options for hook up...Star is typically for starting torque and delta is typically for running efficiency...Any way you shake it winding to winding is the same ohm rating on 3 phase so the meter should read the same from winding to winding...Dual and Tri voltage series or parallel windings to make the motor resistance right for the voltage used...

PS you need a pump curve, wheel size, inlet and outlet to be able to calculate or ft/h20 and GPM, or an engineering degree...

 

[jc55]

Re: how to check the windings on a three phase motor?

The only way to properly check the windings on a 3 phase motor is to actually use a meggar. I troubleshoot 480v 3 phase motors on pumps and valve operators and have had them ohm out fine yet they indicate a short between phases. A meggar will also indicate the 'health' of the windings. Someone with a phase converter may find it useful. My dad runs 3 phase machinery on 110 power. It makes the electric meter run backwards...no lie!

 

[Tim Frank]

Re: how to check the windings on a three phase motor?

It sounds like it may be an effluent pump...in which case, there is probably a market for it with property/building management companies.
Many need these for sewage handdling in their sludge pits.
There may also be a rotation issue with a 3 Φ motor. If it is not correct, reverse any 2 of the 3 line leads.

 

[bigdee]

Re: how to check the windings on a three phase motor?

My dad runs 3 phase machinery on 110 power. It makes the electric meter run backwards...no lie!

Yeah I have heard of that but I have never seen it happen with my inverters....darn!!

 

[hrdwrkingacguy]

Re: how to check the windings on a three phase motor?

For what it's worth a meg ohm meter detects grounds and a volt/ohm meter can't. If you go from one winding to ground with an ohm meter and it isn't opened, there is a short. If you do the same with a meg ohm meter and you get some amount of resistance you have a circuit path to ground...you don't use a meg ohm meter winding to winding(in my experience)...grounds are grounds and shorts are shorts and the are different...

 

[bigdee]

Re: how to check the windings on a three phase motor?

For what it's worth a meg ohm meter detects grounds and a volt/ohm meter can't. If you go from one winding to ground with an ohm meter and it isn't opened, there is a short. If you do the same with a meg ohm meter and you get some amount of resistance you have a circuit path to ground...you don't use a meg ohm meter winding to winding(in my experience)...grounds are grounds and shorts are shorts and the are different...

x2 A megger is used to check for insulation break-down or fault paths to ground. A quality standard multimeter is what the PO should use to determine whether it is 3 ph or single phase.

 

[jc55]

Re: how to check the windings on a three phase motor?

Megger readings between phases will also tell a story of weak windings within the stator. When you're inputting 1000 volts(low amperage), it allows you to see specific resistance numbers. On our valve operators, we do a lot of preventative maintenance. Electrical checks like that, give us a heads up on life expectancy.

 

[jc55]

Re: how to check the windings on a three phase motor?

Oh and to further clarify, It's been my experience that you can "OL" on a Fluke meter (87 5) from winding to ground and still have a short. We have some jacket water pumps that'll run for 6 months, kick out on overload, reset them and they'll run for another 6 before shutting down again...degraded windings which can be picked up on a megger. We see some pretty crazy 3 phase stuff here at the compressor plant that I work at.

I'm not proud of it, but we had a motor that we sent out to be rewound. They mislabeled the phases (stupid me, I usually always check phase rotation). I installed it and it ran backwards for a month and a half...very embarrasing!