2 phase electrical motor not running, help please

[czechsonofagun]

The motor for the table saw stopped running.

Well that's not correct. it starts, flips the breaker and stops. From the sound of it, seems it runs on one phase only. I did the obvious - got new capacitors and swapped them - with zero effect.

The motor is little bit over a year old and it never even flipped the heat protection - because it is 6.5HP at 10" table saw

Please, advise. Next thing I will check is the centrifugal switch, but I am open to suggestions.

I checked the field resistance, checked each field against the ground, the outlet is putting out the correct voltage, I am stumped.

 

[murphy1244]

It is a single phase motor,check the armature. and cord.

 

[czechsonofagun]

No, it runs on 2 phases - 240V - and the cord is ok - gives 240 on the motor. The armature I checked and it is ok too.

 

[greasemonkeyok]

Are you sure it is not 240v single phase? I thought the next step up from single phase is 3 phase.

 

[crash325]

No, it runs on 2 phases - 240V - and the cord is ok - gives 240 on the motor. The armature I checked and it is ok too.

Hi Prokop,
220 / 240 Volt motors are run off of 3 wires ( some have a forth ) You have 2 hot wires and 1 neutral. 4TH is a additional ground. The 2 hot wires switch back & forth (In the motor.) as to which 1 is supplying power.

6.5 HP requires a lot of amps, very few circuits can handle that many amps.

Not an electrician, but have never heard of it being called 2 phase.
3 Phase is the next step and a whole new ball game.

 

[czechsonofagun]

OK, my bad. Overseas we have 3 phases as residential grid and in a brain fart I called this one two phases since it connects to two phases. You guys are right, single phase wired to 240VAC.

The motor was running fine for a year and the breaker never flipped before - lot of power for the mid size saw - but I like it that way.

BTW 3 phase asynchronous motor is one of the best technical solutions out there, simple, strong and foolproof. Too bad it is not available in USA - it is effective and also good for the grid. No capacitors, just goes from star connection to triangle and that's it.

 

[crash325]

3 Phase is available in the US, but not on very many house hold type circuits.
Most large commercial motors use 3 phase. One leg always pushing or pulling. And most of them use 440 Volt power.
There are Inverters (not sure what the real name is.) that will convert your current to 3 phase. No idea how good they are, but do think costly and not worth the trouble.

I would change or replace the breaker. If it has been working at or near capacity heat may have caused it begin failing.
Check motor amps and add 20% for the correct breaker size.

 

[heviduty]

If you replaced the capacitors, the start switch is probably not making good connection. Usually tapping or jarring the motor will do the trick. My table saw occassionally requires a tap or 3 on the motor if it has been a while since I used it. Once it starts the first time, it starts fine until it sets a few months.

 

[czechsonofagun]

If you replaced the capacitors, the start switch is probably not making good connection. Usually tapping or jarring the motor will do the trick. My table saw occassionally requires a tap or 3 on the motor if it has been a while since I used it. Once it starts the first time, it starts fine until it sets a few months.

Start switch - would you mean the centrifugal switch by that? Because I already bypassed my Start/Stop switch.

 

[heviduty]

Yes, I meant to say the centrifugal switch.

...I just reread your original post and you say it starts, then trips the breaker. If it is turning for a few seconds, then tripping the breaker, the centrifugal switch may be stuck closed, keeping the start winding energized longer than it should. See if you can move the weights and make the switch open. It may need a shot of WD-40.

 

[czechsonofagun]

Well it runs now and I have no idea why
Took it all apart, the same thing. Replaced capacitors - same thing. Messed with running capacitors wiring - apparently some time in the beggining I connected them wrong way, they need to be in series.

Soo - there was connection problem or such, I fixed it and got stumped by my own stupidity when I changed capacitors wiring.

 

[hr3]

Good job at least you kept trying,,,:thumbsup:

 

[BobRip]

What is the breaker rating? What is the running current on the motor? It should be on the name plate. The breaker should be at least 1.25 times the running current. If the centrifugal switch does not open after startup this could trip the breaker. You might have some mechanical binding, perhaps a bearing going bad. Nothing that you have said indicated this though.

What you have is single phase. There is such a thing as 2 phase and we briefly studied it in school, but I have never seen it in the seven countries I have visited. It would be nice to have three phase in homes. The equipment is much more reliable, starts better, and last longer. No starting switches or capacitators to fail.

 

[czechsonofagun]

I am resurfacing this to post information that could save somebody some trouble.

The motor, which I now know is 1 phase 240V , stopped running again. Actually it would not start, just buzz and flip the breaker. I took it all apart again, measured resistances and what not with nothing - again.

So I took a vacuum and started cleaning saw dust out, since it can only help. On the end of the shaft there is some kind of a centrifugal switch for start and run circuit switching. I wiggled it back and forth, plugged the motor in and it run just fine.

What was happening is, the switch would due to the saw dust and likely humidity in Virginia stay in the run position when I turned it off, and the run circuit connection would not be strong enough to start the motor from cold start.

Very happy this mystery is solved, hopefully it will save some head scratching for someone.

 

[BobRip]

I am resurfacing this to post information that could save somebody some trouble.

The motor, which I now know is 1 phase 240V , stopped running again. Actually it would not start, just buzz and flip the breaker. I took it all apart again, measured resistances and what not with nothing - again.

So I took a vacuum and started cleaning saw dust out, since it can only help. On the end of the shaft there is some kind of a centrifugal switch for start and run circuit switching. I wiggled it back and forth, plugged the motor in and it run just fine.

What was happening is, the switch would due to the saw dust and likely humidity in Virginia stay in the run position when I turned it off, and the run circuit connection would not be strong enough to start the motor from cold start.

Very happy this mystery is solved, hopefully it will save some head scratching for someone.

I have seen that.

 

[kenmac]

I am resurfacing this to post information that could save somebody some trouble.

The motor, which I now know is 1 phase 240V , stopped running again. Actually it would not start, just buzz and flip the breaker. I took it all apart again, measured resistances and what not with nothing - again.

So I took a vacuum and started cleaning saw dust out, since it can only help. On the end of the shaft there is some kind of a centrifugal switch for start and run circuit switching. I wiggled it back and forth, plugged the motor in and it run just fine.

What was happening is, the switch would due to the saw dust and likely humidity in Virginia stay in the run position when I turned it off, and the run circuit connection would not be strong enough to start the motor from cold start.

Very happy this mystery is solved, hopefully it will save some head scratching for someone.

I haven't seen 1 of these in quite some time. If it's what I'm thinking ,, you are referring to what we ( down here ) call a sail /centrifugal switch. It only makes up when the motor is running

 

[czechsonofagun]

Yes, it looked like this - give or take:

CSW2 20mm

 

[kenmac]

I have seen this switch on motors,but it's been a while. It must be an old motor

 

[buickanddeere]

Domestic 120/240 power is single phase no matter if the connection is line to neutral or line to line.
6.5HP will be the "peak" rating . Continuous will be approx 1-1/2 to 2 HP.What is the nameplate current?
As previously stated a stuck closed starter switch was the likely culprit.