Having Difficulty Sizing IEC Motors?
Find Out the Easy Way to Retrofit IEC Motors
One of, if not THE, most important aspects to replacing an existing electric motor in an application is properly sizing the motor to retrofit the mounting and space available. If all electric motors were standard, this would not be an issue, but, as we all know, “standard” is not only NOT the norm, it is subjective as well.
As a result, it is important to know what to look for when determining if your existing motor is non-standard. This is easier to determine with NEMA motors because changes made to the mounting dimensions by the manufacturer are required to be noted on the nameplate in the frame size. However, that is not the case with IEC Metric motors, and this is why there is so much trepidation and confusion when it comes to replacing an IEC motor.
If the mounting dimension of the feet, base or flange is different than the established dimension for that frame size on a NEMA motor, the manufacturer must note that with a “Y” toward the end of the frame size on the nameplate. A deviation in the shaft dimension requires a “Z.”
This is not true of IEC Metric motors. For instance, the shaft, feet or flange dimension of a D90LD frame could be the standard metric dimensions, or they could be a myriad of other configurations without any deviation noted on the nameplate.
So how does one verify that an “off the shelf” replacement is going to work for their application?
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Posted on: February 11, 2015
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photo by Bark
Nothing short of measuring will solve that problem. Whenever you are replacing an IEC Metric motor for the first time, you must take the time to accurately measure shaft length and diameter as well as the distance from center-of-bolt to center-of-bolt-hole on the feet or across the shaft on flanges and c-faces depending on how you plan to mount the motor. This can be loosely accomplished with a tape measure, but calipers are much more accurate. With all electric motors it is important to verify that the length of the motor will fit in the space allotted as overall length is not a dimension that is standardized in either NEMA or IEC.
Once the basic dimensions are acquired, it is a simple matter of comparing them to the drawings of the potential new motor to ensure that the standard dimensions for that frame size apply. Your customer service representative should be able to assist you with matching the motors. Once the applicable dimensions have been verified, the new motor can be purchased with confidence and installed with ease. There is no longer any reason to avoid replacing IEC Metric motors.
Click image to open IEC / NEMA Dimensional Comparison Chart