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Cincinnati #2 mill starter tripping

Toot Uncommon

Plastic
Joined
Sep 17, 2010
Location
Winder, GA
I would like some help getting a replacement / repair on a starter for an old #2 mill. The starter keeps tripping, requiring resetting of this button:

image2.jpg

I found similar entire starter assemblies on ebay by searching for "709 allen bradley starter" or similar, but found nothing identical. So, if someone could explain exactly how to properly source a modern equivalent that would be great as an alternative to replacing with an original.

Here's more in the way of information about the machine itself:

num2plate.jpg

And:

image4.jpg

Thank you,

Toot
 
Does it run for a “while” before tripping?

What voltage are you running mill on, and is that the voltage heaters were sized for?

You’re picture of the starter would be more useful if it showed the whole thing.

I think you’ll find two “modules” marked Nxx towards bottom of starter. Those are the heaters and need to be sized according to motor full load amp draw (FLA) at voltage motor is wired for.

Often, an industrial machine is wired for HI/480 volts and when run on LOW/240 volts heaters are to small for resulting doubling of amperage.

A more modern starter would have heaters on all three legs, but lots of old AB’s use just two. This is OK mostly....

You probably just need bigger heaters. May not be easy to find.

To give a better answer, requires more back ground info.

Scott
 
The wiring diagram shows overload devices on all three legs. You need to pull one of the overload devices (heaters) and see the marked size. You then compare the size to an appropriate table that lists the size necessary for the full load amps (FLA) of your motor. If you are within an amp or two that is probably not your problem. If, as SVS posted, it is rated for 1/2 full load amps, it is your problem. Finding the correct heaters may be difficult if its an obsolete starter.
 
There should be a heater chart included inside the starter enclosure, along with the schematic you posted (though they can fall out, be painted over, or otherwise destroyed). As others have said, determine if you starter has the correct heaters for the voltage you're running the motor on before replacing the whole unit.

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Was this machine working in your shop and then started acting up or did you just get it home and are having trouble with it tripping?

If you have had it running, it has been my experience that switches don't really go bad like that and I would suspect the heaters are sized for the switch. I'd be searching for an issue that is causing excess load on the mill.

If you have just brought it home, I would give the same advice, but also with the caveat that if it is running 220v instead of 440v, the heaters will need to be changed to allow for the increased amperage.

Peter
 
It was recently installed in a garage and is on a rotary phase converter. Pretty sure the previous owner had it on regular 480.
So what voltage is it on now? If on a rotary converter, I'd assume 240, which would probably meant that the heaters need to be changed out.

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It may need a coil as well as heaters if you are going from 440v to 220v. That is a much easier diagnosis and solution than chasing after an actual trip. There are plenty of mag switch parts on eBay.

Pete
 
It may need a coil as well as heaters if you are going from 440v to 220v. That is a much easier diagnosis and solution than chasing after an actual trip. There are plenty of mag switch parts on eBay.

Pete
Good thought. If it has a transformer to step the control voltage down that could potentially need looking at too.

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Good thought. If it has a transformer to step the control voltage down that could potentially need looking at too.

Sent from my SM-G950U using Tapatalk

My Kearney and Trecker 2hl universal horizontal came from the Navy and was wired for 440....I had to rewire the motor pigtails, change the overloads out for twice the amperage, and as the machine had a 440 starter coil in the square d starter, that had to be changed as well.. You need to make sure that your starter is large enough for the amperage you are going to be using as well...Cheers; Ramsay 1:)
 








 
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