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Allen Bradley Bulletin 712 transformer

M

Mold God

Aluminum
Joined
Feb 14, 2019
Location
Monrovia, CA, USA
This switch/transformer came on an old (WWII) Allen drill press and has worked well for the 30 years I have owned it. It recently melted the core of the transformer (a waxy substance all over the lower switching unit). It was wired for 440 going to 220, 3 phase. Not sure if that had anything to do with the melt down. Am interested in getting the whole panel replaced or fixing what is there, if possible so I can use the drill press again. Any suggestions? I will post photos if that will help.
 
Photos, diagrams, and nameplates would definitely help. It sounds like you're looking at a motor starter, not a transformer.
 
You are probably right, I did not know what else to call it. The only other information I have right now is it uses 440v, 3 cycles. Form 2T, size 1 are also there, I have no idea what they mean. The serial number is 376888. I will post photos next week.

It has been running on 220 for 30 years with no complaints (until the coil melted).

I took it to an electric contractor in town and left it for 2 weeks, they never even looked at it.
 
Pictures here and a bit of info on the coil. I found some writing, hope it makes sense.

440v-600v
637-001-008
X65175 Jefferson
Bellwood, Il.
 

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A-B 712 starters have been obsolete for decades now so part numbers are meaningless, there are no more spare parts. But that’s actually irrelevant. What burned out is the Control Circuit Transformer, it supplies control voltage to the coil of the starter and anything else in the controls. You can replace it with any make of the same size or larger. In those old days it was acceptable to not have fuses to protect the primary (high voltage side) of the transformer, which is why it melted down. Now you would need to have fuses, so get a CPT that has a built in fuse holder.
 
While cleaning out a storage container, I found what may be a solution, depending on the reaction here.

A brand new (but 30 year old stock) AB Bulletin 1497 Control Circuit Transformer. The one possible problem is that it is rated at 75VA, rather than 100 + I have no idea what this might mean. It has a built in fuse, so overloads are not a problem, but is it too weak to even handle the load of being turned on?
 
Bulletin 1947 appears to be the series, not the model. Make sure the primary and secondary voltages are correct.

75VA should be fine for one contactor.
 
Notice in post 5 pic 5 that the transformer is surrounded by four holes at the four corners.
Was another larger size transformer there before? Who knows.

Clean everything up and just get an other control transformer.

Here comes the question:
Is that existing transformer a 240 - 120V ?
Or a 480 -240V with the primary side at 220 and the secondary expected to stay at 110 for a long period of time?

Here comes the Christmas present:
The transformer is the easiest thing to replace. What is above it and below it are not easily replaced.
 
Primary - 240/480, secondary 120 The existing transformer is also 240/480 to 120 if I remember correctly. Will check tomorrow.

As far as I can tell, the burned out transformer was original to the machine, which was built in the 1940s (I think), originally owned by Curtiss-Wright.

Other stuff printed on the box: Series B, CAT 1497-N2 There was no model number.

Thanks for the input! I will try this new one because I have it already. If it does not work, I will find another.
 
rons said:
Notice in post 5 pic 5 that the transformer is surrounded by four holes at the four corners.
Was another larger size transformer there before? Who knows.
Click to expand...

No. Back in the days before CNC, the back panels for standard starters like this were all punched for every possible combination of devices that could go inside.
 
Jraef said:
No. Back in the days before CNC, the back panels for standard starters like this were all punched for every possible combination of devices that could go inside.
Click to expand...

My point is that something could have easily changed given the additional mounting holes.
It's obvious that someone didn't drill those holes. They look too neat.
 
None of the other holes were threaded, nothing else had been there. I tried to mount the new transformer but ran out of talent and time. Will try again when not pressed to do something else. The new transformer is twice the size of the old, I will have to be creative when installing it.
 
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