Square d contacts

[Andrew Hughes]

How do these contacts look the you guys. Too me they look ok but then again I don’t know what burnt one look like. It’s NEMA 1 square d starter 240v 3ph 5hp.
I cleaned up the coil there was a some stuff stuck to coil. But not much.

I think the coil buzzes when my electrical service is soft during the middle of the day.

[David Kumm]

They look bad to me. I just blew smoke out of a starter and the contacts were much better. I may have another problem but it is rare to see smoke from the starter. Better than from the motor. Dave

[Darcy Warner]

Yeah, they are in tough shape.
I have done all sorts of which craft and snake oil repairs to starters that would be very expensive or almost impossible to replace. Square D parts are cheap an easy to get. You should be able to find good used or new on ebay, or find another of the same starters and keep few spare parts around.

[ray grundhoefer]

yep those are toasted, time for new set of contacts

[Malcolm McLeod]

As others have said, you can get re-build kits for Square D starters with no problem, so I'll stick to potential root cause. When a contact closes and the gap reaches a critical point, it will create small arcs just prior to closing. The stronger the coil, the faster the contacts close, and so less arcing. The arc can either weld the contacts closed, or erode them over time as you see here. Lots of factors at play: load, voltage, coil 'strength', start cycles, etc.. Maybe obvious; certainly not magic.

You say the 'coils buzzes' - - Why? I'd suspect the buzz is not emanating from the coil, but rather from continuous arcing across the contacts. If so, it effectively increases your start cycles into the millions. If the coil is going bad, it may not generate enough force to keep the contacts sealed. Or, the coil voltage ('soft during the day') has dropped and the resulting magnetic force is too low. It's even possible someone re-built the starter with the wrong opening spring (too strong).

You may need to look at exactly what is happening across the coil.
Right spring?
Maybe just replace the coil?
Maybe change coil voltage? This might mean installing/replacing a control power transformer, but the secondary voltage may be more stable than the 'soft' primary side??

[Andrew Hughes]

Ok guys thanks. I’ll find a set of contacts .

[Bill Dufour]

Check ebay for used starter. They can be cheaper then a rebuild kit. Tons of square D stuff being sold there.
Bill D.

[Warren Lake]

Malcolm thanks for the explain on that.

IVe had many apart and always had two bumps about .125 size sitting up maybe .060 high and they would have a hard fuzz kind of thing in the middle of the bumps, id take that arcing off and things worked fine, of course there were the times that one little tiny sprig shot across the room and landed in sawdust and of course this was always working late and meeting a deadline.

Ive done alot of work where my on and off switch is me plugging a twist lock into a receptacle which is start, then turning it left and out which is stop. Not ideal but it never failed and the work got done. I have lots of dead switches in the switch grave yard one brand I dont like cause of failures and they are likely gone now. Then Danfoss on one that are 55 years old and work fine, back then they were thick metal bodied compared to todays plastic. I like the look as well round edge like the old Martin machines.

[Andrew Hughes]

I’ll try new contacts first I’ll probably learn more way.
This starter has been in service for about 5 years and it’s first 2 years it did have a had life.I don’t understand what the opening spring is.
9998sl3 is the kit I’m looking at. I see two different types of contacts one has round pad on the ends one is smoother. The ones I have are smooth in the ends.

[Malcolm McLeod]

... the opening spring is. ...

The coil/magnet pulls the travelling conductors 'in' (to contact the fixed conductors). In every mag-starter I've ever been in, there is a spring - of some type - working in opposition to the magnet. It pushes the travelling part back 'out' when the coil de-energizes. If the spring is too strong for the magnet.... well, it could lead to a hard life.

Many contactors have the pads you reference on the end. It is an electrical version of a 'wear' pad. IIRC, most are silver plated, as silver is supposed to resist arcing - or perhaps minimize erosion from arcing? Forgotten the exact theory on this ...its been way too long since a real Sparkie explained it to me.

Just thought of something else to consider - If the travelling part of the contactor is sticking (resin or sawdust?), everything may seem to work properly - but it could be moving too slowly. This increases the amount of time the contactor is within the critical 'arc gap' distance - both on starting and stopping - and so increase the damage. This should not cause the buzz you hear, so probably a long shot, but worth a look...? A good 5hp mag-starter should close with a solid 'thunk'. I have commissioned a few much larger ones that sound like a car wreck.

[Andrew Hughes]

Aww ok I think I know what your talking about . I have not taken that area apart yet I remember seeing white lever that gets moved when the armature is closed to the magnetic coil. That must be where the spring is. I’ll check it out when I get new contacts. There’s some places near by I can scout tomorrow.
Hopefully they are open and not hiding from the virus. One guy is pretty knowledgeable.
Thanks everyone good Luck stay safe.