Motor Rewind Question

If the motor has had a dubious, or even unknown, history, it may be worthwhile considering a replacement motor of the correct voltage, for warranty purposes alone. A machine breakdown may have an effect that is worth far more than the replacement value of the motor.

As always, the value calculation is to be performed locally.

Or the cost of a rewind. You make good sense with your statement.

Hi, it seems that you have a medium size DC motor they run on that voltage 550

Those voltages, 550 and 575, were very common industrial voltages in Canada in the old days. These systems were delta with either one phase grounded, called a "corner ground", or with no phases grounded. These systems have mostly been replaced with 347/600 Y 4 wire systems, but I bet there are loads of legacy 550 and 575 volt delta systems around.

If you do not wish to rewind the motor back to 230/460, you could always check with some of the Canadian surplus dealers if you need a transformer for use with this motor.

It might be wise to open up the ends and replace the bearings, as 15+ years of slow oxidation might give you a motor that starts and soon fails after the correct transformer is found.

What you need is a 3Ø transformer from voltage 1 to voltage 2 of the correct HP rating.

you might also want to have what is called "isolation", as this might be a requirement in the dairy business. I have heard of herds of cattle connected to milking machines all being electrocuted at the same time by a ground fault.

Check the cost of a fixed transformers cost, and see what variable 3Ø autotransformers cost. The variable will allow assorted voltages to be made for various motors you may find. It may be cheap enough to buy a new motor or ask a motor shop to rewind it as a custom motor.

Here is a link batch for that subject.

http://www.google.ca/search?hl=en&q=3+phase+transformer&meta=&aq=4&oq=3+phase

And times change, and sanitary equipment made 20-40 years ago might not be approved for direct food contact these days

A/B,

The 404 frame indicates a rather large frame size for only a 40HP. I am assuming that you are talking of using 230 3Ph AC; in this case, 404/405 frame motors start a low of 50HP (Siemens IEEE841). Also, you did not indicate RPM, and 404/405 motors are generally rated at 900 or 1200 RPM. 404/405's list a shaft size dimension of 2.875 with exception of the 404/405TS (short shaft / 3600 RPM), which is 2.125.

What is your application? Do you need a ball bearing drive end or tapered bearing drive end? Chemical environment? These are things that will determine if you have a "bargain" or need to look elsewhere. Incidently, if I were going to take a motor that had sat up for years and rely on it for production, I would most certainly have it rebuilt (including checking the iron, baking and stator checks)...and all of these, do not make for a cost effective solution for only a 40HP, unless of course it is a special application and a replacement is not available.

let me know if we may be of assistance / old golfer

Suggest you run the motor on no load and measure current if you have a supply of 575V

Remove the ensdshields and examine the leads that are connected to the winding. From the connections you will be able to see if the motor is converted to higher voltage by reconnecting the leads. If this is the case, motor can be reconnected to 230/460V.

Otherwise it has to be completely rewound which can be done.

Buy a new replacement motor, whatever you pay out on the old one still means you still have an old one.....

Plus if the "repaired" one breaks and you have to buy a new motor, that "repair" money will be strongly regretted!!!