# Will Vibration cause a motor contactor to drop out?



## Peewee0413 (Oct 18, 2012)

Ive seen stripped terminals wiggle with vibrarion and drop out a latch. 

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## wildleg (Apr 12, 2009)

it should probably be a mechanically held contactor. If not, it is possible, but not for sure that is the problem. if it is mechanically held I would be inclined to think that it was not the issue.


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## 460 Delta (May 9, 2018)

You might want to look at the aux contacts and consider changing them. A starter isn't really designed to be shaken a lot, so the aux contacts could be the problem.


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## splatz (May 23, 2015)

I am assuming the operator confirms it shuts when it's shaking. When it's rocking and rolling hard enough to shake the control cabinet, is the grinder hood moving enough to open that switch, or is the stop switch shaking enough to unlatch the circuit?


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## 460 Delta (May 9, 2018)

This may be a good place to use the 1/4 amp fuse trick to find the contact that is opening splatz.


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## splatz (May 23, 2015)

460 Delta said:


> This may be a good place to use the 1/4 amp fuse trick to find the contact that is opening splatz.


I don't think I know this one, where would you put them?


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## Wirenuting (Sep 12, 2010)

Welcome to ET,
Please take the time to fill out your profile. 

Also, tell the operator to stop overloading the grinder. 
It’s a grinder not a shaker machine. 

Check the contacts on the push button stations & aux contacts. 
Cheap plastic 22mm switches don’t last.


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## Wirenuting (Sep 12, 2010)

..... double post ....


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## gpop (May 14, 2018)

Put a fuse that can not carry the load in parrellel with a switch. If the fuse blows it indicates the switch opened

You have 3 switches on a basic start/stop button set up. Just need to see which one opened first.


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## 460 Delta (May 9, 2018)

^^^ yep Splatz, what gpop said.


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## Wirenuting (Sep 12, 2010)

I wonder if he looked at the anti-vibration switch on the motor, frame or bearing?
Just a thought.


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## splatz (May 23, 2015)

gpop said:


> Put a fuse that can not carry the load in parrellel with a switch. If the fuse blows it indicates the switch opened
> 
> You have 3 switches on a basic start/stop button set up. Just need to see which one opened first.





460 Delta said:


> ^^^ yep Splatz, what gpop said.


OK I was actually thinking of something along those lines but wouldn't you have to size that fuse carefully - less than the coil amps, but more than half the coil amps?


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## gpop (May 14, 2018)

splatz said:


> OK I was actually thinking of something along those lines but wouldn't you have to size that fuse carefully - less than the coil amps, but more than half the coil amps?


Nope you just need a fuse that will blow. Its not protecting anything. Its just there to blow as a indicating device.


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## Rora (Jan 31, 2017)

Brilliant trick, never heard that one before!


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## splatz (May 23, 2015)

gpop said:


> Nope you just need a fuse that will blow. Its not protecting anything. Its just there to blow as a indicating device.


I think I follow, as long as it's lower than the control current, it will blow when the switch opens - but if it is in parallel with the switch, each will carry half the control coil current until the switch opens.


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## gpop (May 14, 2018)

splatz said:


> gpop said:
> 
> 
> > Nope you just need a fuse that will blow. Its not protecting anything. Its just there to blow as a indicating device.
> ...


No potential across a closed switch so nothing to half


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## gpop (May 14, 2018)

I think you have a valid point splatz. I would have to bench test to see what the fuse is carrying. I know it works as i have used it in the past just never thought of the physics behind it.


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## John Valdes (May 17, 2007)

I would look at any safety switches. Covers and guards.


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## Rora (Jan 31, 2017)

Resistance is inversely proportional to area. The contacts likely contains a much larger cross-section as the tiny fuse filament. Let's say the fuse is 10 ohms, and the contact is 0.1 ohms... that means the circuit would have to carry over 25 amps to blow a 250 microamp fuse in parallel.


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## just the cowboy (Sep 4, 2013)

*Fast acting at little over half the coil current*



gpop said:


> I think you have a valid point splatz. I would have to bench test to see what the fuse is carrying. I know it works as i have used it in the past just never thought of the physics behind it.


It should be a fast acting fuse at just over half the coil current. Just the differance between the element resistance and the contacts resistance will cause most of the current to flow thru the path of least resistance the contacts. 
@gpop didn't know others new this one.


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## JRaef (Mar 23, 2009)

I doubt it is the contactor or aux contacts, there are NEMA specifications for vibration that have to be met. I have put countless starters on the sides of rock crushers without problems.


What I HAVE seen on numerous occasions is Normally Closed push button contacts vibrating open. You say the starters are A-B, but are the buttons as well? I see people cheap out on the pilot devices because they assume that they are all the same, but that's just not true. ABB push buttons are notorious for that, but I've seen it on off-brand cheap stuff as well. I had to stop using ABB pilot devices on the crusher panels I built, I just couldn't get the E-Stop buttons to hold in. If it's fairly consistent, put a temporary jumper in around the Stop contacts and see if the problem goes away (make sure EVERYONE knows there is no E-Stop). If the problem goes away, replace then with another brand.


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## gpop (May 14, 2018)

just the cowboy said:


> It should be a fast acting fuse at just over half the coil current. Just the differance between the element resistance and the contacts resistance will cause most of the current to flow thru the path of least resistance the contacts.
> @gpop didn't know others new this one.


Cut my teeth on relay logic where you play guess which relay opened first. Another trick is to make a self latching relay and i still use that one to prove that i lost power for a split second.


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## benwinch07 (Dec 18, 2018)

splatz said:


> When it's rocking and rolling hard enough to shake the control cabinet, is the grinder hood moving enough to open that switch,


Winner Winner chicken dinner! 

Thank you all for your awesome input! Some really great ideas and methods!

Since our Safety coordinator will rip us a new one for troubleshooting while the machine is on (probably for good reason, big picture wise, but thats a whole other rabbit hole in itself), The safety switch always had continuity while the machine was down and not shaking. I just happened to notice that some of the big ol' wingnuts that flip up and tighten down on the hood weren't all the way tight. I tightened them down and its been good ever since. 

Sometimes I miss the simplest things :vs_laugh:
The operator cleans the thing out and reassembles it so theyre supposed to tighten it down. Usually if they dont tighten it enough it wont even turn on. 

I love the fuse idea! If Im understanding it right, you would use the fuse to jumper across the contacts, sharing the load going through the button? And if the contacts open up, the whole load will go through the fuse and blow? Thats ingenious.

As far as telling the operator to not overload the grinder...They "only throw two or three sheets in at a time" so my efforts are better spent in other areas, lol.

We do primarily buy AB switches and buttons. Sometimes Schneider. Good to know about ABB though, I'll keep that in mind.

Thanks again, guys, I loved hearing from you! 
Cheers!


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## Switched (Dec 23, 2012)

@benwinch07, thanks for posting the fix! I like these threads about stuff I never work on, especially when I get to hear about what the actual issue ended up being.


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## 460 Delta (May 9, 2018)

Thank you for taking the time to tell us what the problem was and the repair worked out to be, it helps us to all be better electricians. I try to file away info from this stuff and modify it to help in my day to day work.


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## MikeFL (Apr 16, 2016)

Ditto on letting us (and anyone who encounters the thread) know the outcome. It's rare all too often.
Glad it worked out for you.


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## splatz (May 23, 2015)

Thanks for the follow up, plus for a question that got @460 Delta to bring out one a real good one from his bag of tricks, I am going to be experimenting with that one in the Laboratory (basement). 



benwinch07 said:


> Winner Winner chicken dinner!
> 
> Since our Safety coordinator will rip us a new one for troubleshooting while the machine is on (probably for good reason, big picture wise, but thats a whole other rabbit hole in itself), The safety switch always had continuity while the machine was down and not shaking. I just happened to notice that some of the big ol' wingnuts that flip up and tighten down on the hood weren't all the way tight. I tightened them down and its been good ever since.
> 
> I love the fuse idea! If Im understanding it right, you would use the fuse to jumper across the contacts, sharing the load going through the button? And if the contacts open up, the whole load will go through the fuse and blow? Thats ingenious.


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## gpop (May 14, 2018)

benwinch07 said:


> Winner Winner chicken dinner!
> 
> Thank you all for your awesome input! Some really great ideas and methods!
> 
> ...


When you get bored take a look at the safety switch and see if you can make a self latching relay (just about the same setup as a hard wired start/stop starter set up except you are latching a relay rather than a contractor). Hook a indicating lamp and a reset button on the outside of the panel for the operator.

Then any time the machine shuts down due to the door switch the light will come on and stay on indicating that was the problem. Keeps safety happy as you do not need to open the door, keeps you happy as the operator doesn't need to disturb you tea breaks.


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## MikeFL (Apr 16, 2016)

gpop said:


> When you get bored take a look at the safety switch and see if you can make a self latching relay (just about the same setup as a hard wired start/stop starter set up except you are latching a relay rather than a contractor). Hook a indicating lamp and a reset button on the outside of the panel for the operator.
> 
> Then any time the machine shuts down due to the door switch the light will come on and stay on indicating that was the problem. Keeps safety happy as you do not need to open the door, keeps you happy as the operator doesn't need to disturb *your tea breaks*.


I was in a very nice restaurant for lunch a few years ago, up north, and when the waitress asked what I want to drink I said I'll have a spot of tea (meaning a cup of hot water & a tea bag with sides of sugar & cream). She was quite dramatic. "What the hell is a spot of tea?..." 
@gpop is a transplanted Brit living in our beautiful state of Florida. You can catch those subtle nuances in his posts. He brings a considerable wealth of knowledge to the forums.


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## just the cowboy (Sep 4, 2013)

gpop said:


> Cut my teeth on relay logic where you play guess which relay opened first. Another trick is to make a self latching relay and i still use that one to prove that i lost power for a split second.


Me too before PLC's, like me I guess you did tube drives for varable speed motors. 

I am doing the latching trick right now with a small PLC for troubleshooting a relay logic problem. 
Nice to see the old skills still at work.

Cowboy


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## Peewee0413 (Oct 18, 2012)

just the cowboy said:


> Me too before PLC's, like me I guess you did tube drives for varable speed motors.
> 
> I am doing the latching trick right now with a small PLC for troubleshooting a relay logic problem.
> Nice to see the old skills still at work.
> ...


I still to this day do the latch trick occasionally... actually made a box with a light to see from a distance outside of panels.

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