Failed motors: rewind or replace?

For many process users, the issue of whether to replace a failed motor with a new energy-efficient model or to repair the existing failed unit has not been so easily resolved. Many companies have never developed firm guidelines or policies regarding the replace/repair issue; therefore, many failed motors are simply repaired, sometimes repeatedly, almost by default. Generally, the apparent cost to repair a failed motor (above approximately 15 hp) is less than that of a new motor. The Energy Act of 1992 does not address this issue-there are no efficiency guidelines that must be met with a repaired unit. This article suggests that a more formal approach should be taken when making the repair/replace decision. Consideration should be given to many other factors in addition to the initial cost comparison. Such factors would include: motor age and condition; motor operating and rewind history; motor type and application; motor specifications; applicable utility rebates; and potential energy savings. Potential energy savings can be quantified if the present efficiency of the failed motor is known or can be estimated. The effect of a utility rebate, should one apply, is also easily quantified. Many of the other factors, however, are more subjective in nature and are not so easily evaluated. Nevertheless, these factors should also be considered in the overall decision-making process, as they can have a significant impact on future plant operating costs and reliability.