3 Phase Motor making new sounds

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Gator-J

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I finally decided to clean up my electrical a little and get rid of the wire nuts that were holding everything together on the floor (got shocked from the converter cap discharging I think, and did not care much for it).

So now I have a rotary phase converter running to a switch panel that I am using to distribute to 3 different machines (not at the same time).

Anyway, when I got done with everything the mill seems to run fine but the lathe now makes a loud ticking noise when I run it. I am pretty sure I have everything wired exactly how it was prior to me messing with it.

I do not know much about 3 phase motors, but if I had one of the legs switched could that be the issue? Oh, the motor has a single phase electric brake that pulls off of 2 legs at the motor.

I have always had a weird sound if I put it in reverse when it first starts up, but I use reverse so rarely it never bothered me. It probably needed to be torn down and rebuilt when I initially got it since I have no idea how long it had been sitting, but that was not in the cards at the time. Now it would be a real chore to get the motor off the lathe since it is in a awkward position almost 6' off the ground.
\
Thanks,

Jeremy
 
Hard to say what the new sound is from, but if you have any tow legs swapped, the motor would be running reverse to what you had before. One thing I'd look at though, is if there are control transformers, make sure the taps that are used on the primary side are getting the voltage they are marked for. Some 3 phase has a leg that is higher than the other two, and can cause issues with all the low voltage side equipment. Just a thought.
 
Gator-J said:
I finally decided to clean up my electrical a little and get rid of the wire nuts that were holding everything together on the floor (got shocked from the converter cap discharging I think, and did not care much for it).

So now I have a rotary phase converter running to a switch panel that I am using to distribute to 3 different machines (not at the same time).

Anyway, when I got done with everything the mill seems to run fine but the lathe now makes a loud ticking noise when I run it. I am pretty sure I have everything wired exactly how it was prior to me messing with it.

I do not know much about 3 phase motors, but if I had one of the legs switched could that be the issue? Oh, the motor has a single phase electric brake that pulls off of 2 legs at the motor.

I have always had a weird sound if I put it in reverse when it first starts up, but I use reverse so rarely it never bothered me. It probably needed to be torn down and rebuilt when I initially got it since I have no idea how long it had been sitting, but that was not in the cards at the time. Now it would be a real chore to get the motor off the lathe since it is in a awkward position almost 6' off the ground.
\
Thanks,

Jeremy
Click to expand...

A lot of brakes make a click when they turn on - least on single phase machines I have that have them. Try disabling it and try just power cycling it without the brake. Start the troubleshooting there.
 
bloomingtonmike said:
A lot of brakes make a click when they turn on - least on single phase machines I have that have them. Try disabling it and try just power cycling it without the brake. Start the troubleshooting there.
Click to expand...

I will give it a shot, but it is constant tick tick tick tick tick.

It does make a loud tick when it turns on, I think that is the magnets pulling the pads though.
 
the tick tick tick may be the sound of the capacitor discharging .. i would definitely take a look at that as well as the wiring.
the capacitor should be on a momentary switch not wired in series.

i can explain better if you need clarification .
i'm happy to help.
mike:))
 
Is the noise coming from the phase converter or the motor? I would also start with brake.
 
Morning Men.

Let's start at the beginning. Remember, motor brakes are electrically released, mechanically held. If the brake did not work the motor would not turn.

Next, the HIGH leg Tony mentions is only found in a 240v delta system. Derived basically because the power goes through one and one half windings to reference to neutral. Glance at a schematic, that is why the neutral, or grounded conductor is derived from the center of the delta or triangle drawing. As opposed to a "Y" connection where the neutral or grounded conductor emanates from the center of the "Y" connection giving 120v to ground off of any of the three legs but only 208volts between phase conductors. Now before you get excited, the motor does not give a rip whether it sees 240v, 220v, or 208v. It will draw just a corresponding small amount of amperes, more or less, depending on voltage applied. Those little amps are pretty cleaver that way! The high leg only applies when connecting an item from phase to neutral. Two legs are 125v to ground and the third (high leg) is 196v to ground. Connecting from phase to phase is always 240v, no matter which two of the three you choose. Now 196v will generally let all the magic smoke out of a 120v device.

Good idea checking the fan blade housing but normally it would be a constant screech instead of a tick. (1800 ticks per minute) I'd go more for the lacing on a flat belt striking the drive pulley. Louder now because you are more aware of it. Does it tick at the same rate in reverse? Motor bearing tick can sound that way if you have a bearing that has a flat spot on it. Or a nick in the bearing race. As hard as a bearing is it sounds impossible but I have seen it.

Another note also. Whether it is 115v, 117v 120v, 125v, or 130v. Whether it is 208v, 220v, 230v, or 240v, or 250v. It is all the same for our purposes. It is either low or high voltage in a residential environment. 480/277v only applies to commercial/industrial installations. The bible (Code Book) says we are not allowed to install the latter unless "accessible only to qualified personnel." And that generally is not you.

Once more I spew, but it is hard for me to try and be sure I say it so you understand. I am trying to help, not belittle, or get you in trouble. Just the opposite is true.

Now go make some SWARF!

Just love that word!

Sorry U.D. But the starting switch is definitely wired in series with the capacitor and starting winding. The capacitor and starting winding are then wired in parallel. The capacitor discharges to give the rotor a little bump to get off zero and the starting winding tells it which way to go according to the direction of current flow in that winding at the instant of start. Motor comes to about three quarter or greater speed and the centrifugal starting switch opens and it runs off the running winding which is the one with the larger wire and lower resistance. Remember the time factors we speak of is the speed of electricity. Or more to the point, the speed of light.

Understand? Got it? :allgood:

I knew you would.
 
Last edited:
Sorry U.D. But the starting switch is definitely wired in series with the capacitor and starting winding. The capacitor and starting winding are then wired in parallel. The capacitor discharges to give the rotor a little bump to get off zero and the starting winding tells it which way to go according to the direction of current flow in that winding at the instant of start. Motor comes to about three quarter or greater speed and the centrifugal starting switch opens and it runs off the running winding which is the one with the larger wire and lower resistance. Remember the time factors we speak of is the speed of electricity. Or more to the point, the speed of light.

Understand? Got it? :allgood:

I knew you would.[/QUOTE]


Sorry rdh2,
the start switch should be isolated from the phase converter, every time a slave motor is powered up the start capacitor will
unnecessarily dump it's charge into the 3 phase circuit that has already been created by a running Idler motor.
once the idler motor is running there is no need for the start capacitor, that's why we take it out of circuit.

3 phase motors don't have starting windings, and don't have running windings, and they sure don't have centrifugal switches either for that matter.
i think you are confusing single phase and three phase motors.

(Understand? Got It?:allgood:),thank you, i'm well versed in the theory and functions of 3 phase motors and single phase motors,
perhaps i could offer some tutoring should the need arise, i promise to help without being condescending.

mike:))
 
Hey Mike...

FYI: I'm not nit-picking so, please don't interpret it that way. Just passing-on a little factoid that you might find interesting. Electricity travels at roughly the 70% the speed of light when traveling in a typical metal conductor. For ultra super-cooled (as in liquid nitrogen) systems, it gets up to the 95% range. And on a similar matter, light itself slows down in air, glass or other mediums with a ballpark figure of 75% (much less for air) but, it's really different for different wavelengths. Matter of fact, that's how prisms work... Different wavelengths are slowed down by different amounts and because of the geometry of the internal reflection the effect is compounded. As you change the angle of the prism, you see a color that happens to be making it through better given the distance it's traveling through the glass.

Ray
 
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