Another 3 Phase Problem....

gordfraser

Hi. I had a magnetic starter problem with my planer some weeks ago.
Thanks for all the help.

Now the magnetic starter has (not an overload) gone...i think, but i would like to check out the motor while the new part is being sent.

What sort of readings (ohms.....?) should i get of the 3 phase motor if everything is ok



I think my problem was caused by some slack connections in the controle box (to the trancformer) you can see in the pic where L2 got a bit hot. The wire also showen scorch marks.

L3 is the manufactured leg and does not go throught the controle curcuit

TIA

G

Attached Images

 

Sparky Joe

If your heaters(overloads) didn't open the circuit then the motor is fine. Resistance through your motor will only read around 1 ohm, but you have to understand that you're reading the resistance of the wire in the motor. It's not until the motor is turning until the motor produces it's own resistance within its windings(though it's called inductive reactance, not resistance); this also explains 'inrush' or 'starting' current.


From what I can see in your picture, your control circuit is fine (control circuits are not 3 phase taps from L1 and L2 only)and you had a problem with one of your terminal crimps to the motor off the load side of your starter.

RobertWilber

Looks like the remains of a loose connection
motor problems wouldn't do that at the starter
something at the starter did
wire looked hot? probably was!

CE1

Telemecanique IEC contactor. Piece of junk IMHO

mdshunk

That is what every IEC style contactor will look like when it is loaded near its upper limit. For that reason, I always prefer NEMA style contactors. That's not an option for you, due to the space constraints. In fairness, that could have been a loose connection, but it pleases me more to blame it on those piece of crap IEC style contactors.

RobertWilber

hey md
new picture!

CE1

Charlie is Baaaack!

CE1

Nothing like a Allen-Bradley 709 motor starter
The things work Forever.

Do you guys see an overload module in the picture I can't?

DaveTap

Was there anything connected on the L3 terminal besides the one extra unused wire? If not can't you isolate it and move L2 wires to L3 to run the planer?

gordfraser

Thanks for the help.
I put a new magnetic starter on and it worked fine.
to answer some questions:
the offending article was used to start a 3 phase motor (L1, L2, L3 were used)

The slack (suspected ) wire was not the L2 (burnt) one , but one of the feeds to the trancformer that supplied the controle circuit (of L1 + L2)

so i suspect the starter was turning on and of very quickly for a while and looked like it burnt some of the contacts....could this have made the motor run on only some of the legs, and caused the L2 to overheat??? (sounded logical...from a woodworkers point of view)

I thought that Telemecanique were a good make (again from a woodworkers point of view)


Thanks again

G

mdshunk

Well, it is, as far as IEC style crap goes. Telemechanique is Square D's IEC division. Square D makes the NEMA style stuff, and Telemechanique makes the IEC style stuff. If I must replace IEC style stuff, Seimens is often cheaper. In your case, you were just replacing the contactor portion, and keeping the overload (I think). To do that, you need to keep the same brand so that the pins on the overload line up. If you were replacing the whole shebang, you could have used any IEC style contactor and overload assembly, and clipped it on your DIN rail in that enclosure.

Whatever, it's water under the bridge now. Best of luck to you.

Sparky Joe

I'm having a hard time with that statement, but it looks to me like your control circuit are the 2 black wires on the top left. Perhaps there's something I don't know about iec starters, but I always thought the load side was on the bottom?

Nevermind, guess I finally read what you said, "the burnt wire was not the problem"

Though, if anything failed in the supply of the control circuit the starter would have opened and nothing would work. If something were wired wrong, for say the holding contact was wired through a normally closed contact instead of normally open you would get what you were saying about it opening and closing very fast (and your start button wouldn't work and stop would be the opposite of a 'jog' button)though that wouldn't single phase your motor, it would still open and close all three phases at the same time. I'm still just wondering how that one terminal got so hot, must've somehow been the weekest of the three.

By the way if your motor was run single phase (one of the phases dropped out) it would've seriously overheated the motor and you would've been buying a new one of those.

CE1

Check out the difference between a IEC motor starter and a NEMA motor starter. These would be for the same size motor, except for changing the overlad heaters on the NEMA contactor and adjusting the setting on the IEC contactor. The big difference in physical size is a good indication as to durability!

Attachment 3379

Sparky Joe

Just to clear things up, most guys have never bought and installed as an individual unit an IEC starter. When buying off the shelf to field build a motor starter panel anyone would opt for the NEMA. Although when you buy a control box that's been coordinated specifically for a certain motor then it will have IEC starters pre-installed at the factory.

In short you didn't buy a piece of sh!t, probably just loaded down your motor and something failed