A question for the ages, Should you purchase a spare electric motor to have "on-hand" in the event your motor fails? A simple question but there is no clear answer out there. The reason for that is because it all depends on your situation, the type of motor, and the criticality of the driven machine.
Electric motors can be standard and readily available. Electric motors can also be complex and hard to find. Below are some questions to get us pointed in the right direction:
- Are your motors NEMA regulated frame sizes?
- Are your motors catalog items and stocked by various manufacturers and distributors?
- If your motors are not catalog or standard, how long will it take you to get a replacement?
- How long would it take to repair a motor if it failed?
- What would downtime cost ($$/Hr) be if the machine cannot run?
- Do you have a Predictive Maintenance (PdM) program in place?
- Do you have storage space that will allow for proper storage of spare motors?
When you SHOULD buy a spare motor:
- If your downtime cost exceeds the price of the spare, and proper storage is available
- If the lead time on a replacement motor is longer than desired and proper storage is available.
- If you have no PdM program in place and are not sure when units will fail or not (we do not recommend this!!) and proper storage is available.
- When you are constantly paying overtime charges to repair items in a breakdown situation and the overtime charges add up to be more than the spare motor cost!
- Various other situations...
When you SHOULD NOT buy a spare motor:
- When you do not have proper, temperature controlled, storage space for a spare motor and would not plan for routine maintenance on the spare motor.
- When your motor is readily available from multiple sources and downtime costs are minimal.
- When spare "systems" are in place and the time to get a replacement or get the unit properly repaired is acceptable.
- When the cost of the spare motor far exceeds your estimated downtime costs, remembering to factor in cost per hour until the machine is back up and running.
- Various other situations...
Where do you go from here?
As you can see there are situations when you should buy a spare as well as situations when you should not buy a spare. You must perform an evaluation on your equipment to answer the first set of questions and gain an understanding of what your electric motor population looks like. Without knowing what you have and what the cost and lead time of replacement motors looks like - it can be difficult to formulate a decision.
It never makes sense to buy a spare motor if it is not going to be properly maintained. What's the point of having a spare if, when you go to use it, it fails quicker than the last one did? There are a variety of concerns on how to properly store and maintain spare motors - if you cannot do these items then it most likely will not make sense to invest in a spare motor.
What if no replacement is available? We here this all the time - old, obsolete equipment where you cannot buy a spare or replacements. We like to think that this is malarkey and we just need to think outside of the box to find a spare motor solution.
One last thought: Spares can be planned and budgeted to be purchased. Failures are unplanned in nature and very difficult to budget!
HECO - All Systems Go
About the author:
Justin Hatfield is Vice President of Operations of HECO. He is responsible for Electric Motor & Drive Sales, Electric Motor & Generator Repairs, Spare Solutions, and Predictive Services. Justin was instrumental in developing HECO MAPPS(Motor And Powertrain Performance Systems) which focuses on “why” you have a motor problem instead of simply “What” product or service should be recommended. HECO is an EASA Accredited Service Center.