Three Phase Magnetic Starter Just Stopped Working, Help?

This looks like a discontinuity in the start pushbutton or the two wires attached to it.

i will look into this continuity in the start stop button and wires.............thank you very much.........regards bill abbott

Seems that the coil might have to be replaced if I am interpreting your description properly.

Another item to check would be the control transformer secondary voltage. Voltage should be as indicated on the control transformer name plate.

NOTE - If your operating from line voltage for the control circuit there will be no control transformer.

Make sure the mechanism itself is not binding.

Lastly, check the start stop contacts, the start/hold contact on the starter as well as the wiring in between.

Weak coil or low control voltage is my bet.

i am checking ...............mechanism is ok not binding................line voltage no transformer...............next is start stop contacts.....start hold contact..........wiring i will check again....................get back to you............thank you very much....regards bill abbott

Do you have full voltage across the magnetic coil when the start button is depressed? If you do then the problem is a failing coil which needs to be replaced. Or the there is a problem in the mechanics. Could be just gummed up. Have seen where some one has spilled something on top a panel and just enough got in a starter became tacky and kept it from closing.

If you do not have full voltage when the start button is depressed then look for a voltage drop else where in the circuit.

OK ..............THIS COULD BE IT..............I'LL CHECK VOLTAGE AT COIL ...............I WILL GET BACK TO YOU AFTER I GET VOLTAGE READINGS ...........THANK YOU VERY MUCH ...REGARDS BILL ABBOTT

GA

90% of the time there is an issue with the inrush current required to energize "pull in the coil". Dirty contacts loose wires on the start button could do this.

As ozzb stated check the voltage across the coil after it has pulled in. By holding the button and pushing in the contactor you have replaced the inrush current required to pull in the contacts. If the voltage is good then it is probably the coil that is leaking or breaking down causing it to bleed out.

The reluctance in the magnetic circuit of the contactor is much causing restrictions and free flow of magnetic flux. The major cause of of magnetic reluctance in contactors are corrosion due to exposure to hazardous conditions and high humidity areas. The solution to your problem is constant servicing of the contactor. This can be done by using emery cloth or other cleansing material to clean the attracting faces of the moving and stationary magnetic core. After the cleaning, smere the surfaces with a none corrosive oil. Also make sure the sliding rails of the moving core, that is carring the contacts, is free from any kind of obstructions. That's the solution to your problem since every other parameters are ok. Take Care.

A note on larger contactors: some have a two part coil, one part of the winding is used to pull the contactor in, the other to hold it in. This type has a aux contact wired to the coil which takes part of the coil out once the contactor is in to prevent heating and increase coil life. The disadvantage is that it adds another item to trouble shoot when it fails.

Ahh, that is triggering my memory as well--iirc, some coils for AC contactors also include a shading coil. (I know some single phase motors have shading coils, but I'm 95% certain some contactor coils do also.)

If the shading coil is defective, you'll probably get a lot of vibration / buzzing--the shading coil is designed to sort of "even out" the magnetic flux from an alternating current source so that the magnetic force is more consistent (less "vibration").

The shading coil does not have external connections, but instead is a conductive loop (often copper) embedded somewhere in the (usually) face of the magnetic pole piece. Sometimes the conductive loop breaks.

That could be the problem here.

THE ANSWER IS THE COIL ................MAKE SURE VOLTAGE OF COIL MATCHES VOLTAGE AVAILABLE TO POWER IT...........!!!!!!! WHEN REPLACING IT............REGARDS BILL ABBOTT

I WANT TO THANK EVERYONE THAT PARTICIPATED IN THE DISCUSSION FOR HELPING ME ON THIS PROBLEM.........! I CHECKED EVERY ITEM MENTIONED IN THE FEEDBACK SO EVENTUALLY I GOT IT..............ALSO IT GAVE ME A MORE COMPREHENSIVE UNDERSTANDING OF HOW EVERYTHING WORKS..................THANK YOU VERY MUCH REGARDS BILL ABBOTT