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An engineering manager who works at Smith Services, one of the sister brands that work with us and are a part of Timken Power Systems, answers some questions regarding medium voltage industrial motors and motor repair.

Q: What does an engineering manager do at a repair facility, and what are your qualifications?

A: An engineering manager oversees everyday electrical and mechanical engineering operations. While not all engineering managers have the same credentials, I earned a dual degree in electrical and mechanical engineering.

Q: How does your repair company compare in the industry?

A: As a very active member in the EASA community, we are the largest electric motor repair shop in the eastern-half of the United States. EASA (Electrical Apparatus Service Association) is a leading resource for providing specifications and standards for electric motor repair or electrical mechanical equipment, and their website probably lists over 1,000 service centers in the United States. Even though there are a lot of competitive repair shops in the country, most motor repair services are local, generally work on small, low voltage rated motors. We are prepared to repair a wider range of motors and offer a wider range of repair services to our customers.

Q: Can you provide some detail regarding medium voltage motor classifications?

A: Medium voltage motors are classified through voltage ratings, with 2,300 volts being a common voltage rating for motors in this class. Medium voltage motors fall into the 1,000 volts and 13,800 volt range. 240 volt or 480 volt motors are common industrial voltages used for sub-hundred horsepower applications, but for larger horsepower equipment, lower voltage ratings become cost prohibitive to operate. By switching to higher voltage systems, and providing additional insulation protection to contain the voltage, it is possible to realize exponential gains in motor efficiency.

Q: For what applications are medium voltage motors most commonly used?

A: Medium voltage motors are the preferred option for industrial operations that range from 200-300 HP, up to 700 HP. There is an even distribution of sub-600 voltage equipment and equipment that runs on more than 1,000 volts, but when additional horsepower is required, medium voltage motors or larger offer significant advantages. Medium voltage motors are the preferred choice for mission-critical applications because of their efficiency, reliability, and savings in operating costs.

Q: What criteria is applied when selecting a motor?

A: The specific application requirements provide the motor selection criteria, and the best option is derived from an analysis of the application type and its associated operational details. For example, thermal control is a key factor in the design of compressors because they are usually subjected to high amounts of stress. Pumps and fans also have specialized requirements, and belt drive applications need motors that can accept a significant amount of radial loading. Motor selection for centrifuges and other specialized equipment requires considerable expertise to make the best selection.

Q: Is it common for industries to use medium voltage motors in their daily operations?

A: Medium voltage applications are used throughout every major industry in petrochemical, pulp and paper, metals manufacturing, and power generation processes across the country. Fifty years ago, industries depended more on their location, and industries like pulp and paper mills located near water sources, with less regard for the power infrastructure. Now new plants select a location that optimizes the use of medium voltage motors on the power grid.

Q: Do most motor repair facilities offer repair services for medium voltage motors? A: No. Because most repair services are highly localized, very few are equipped to service medium voltage motors. There are also repair companies that repair high voltage equipment, classified at 13,800 volts and higher. These repair companies are also much less common. Our company conducts all of the necessary electrical tests in the field, troubleshoots breaker systems and transformers, and our highly trained staff can work on-site or in the machine shop.

When large equipment is not feasible to transport, specialized onsite large motor repair is available, and a full array of large motor repair or large generator repair services is available in-house for medium voltage equipment. Our company is associated with the Timken Power Systems’ network allows us to provide our customers access to the large motor facilities in the network. While we focus primarily on electrical motor repair services, such as servicing the driver, switchgear, and repairing the transformer the expanded scope of capabilities enables us to repair medium voltage motors and equipment for nearly three-quarters of the eastern United States within eight hours.

Q: Please describe the details regarding your company’s load testing and spin test capabilities?

A: A facility needs ready access to available power sources to carry out validation testing for medium voltage motors, and apply the power source to that particular motor. A dedicated 2,500 KVA test center gives our company access to properly calibrated power sources and the ability to test all of the medium volt classifications, such as 13,800 volts, 7,200 volts, 4,000 volts, and 2,300 volts. A dynamometer with a capacity of 12,000 lb-ft of torque, equates to 2,500 HP at 1,200 RPM, and makes it possible to test a 5,000 HP motor. With a full complement of documentation at proportional values, this validation capability gives us a distinct advantage over our competitors.

Q: Could you describe the different types of warranties offered by your repair company? And what is your attitude regarding maintenance?

A: We are a highly respected repair company with decades of experience in the industry, so we are confident in the level of repair services we provide. Our warranties are the same for any of the motors we service, so customers receive up to 6 months on the shelf, and a year in service for low voltage or medium voltage, whether they have large motor or large generator ratings.

We made some short term exceptions in the past for manufacturers involved with random wound equipment in medium voltage, in a 2,300 volt class. Because the OEMs pushed the design envelope, some of these motors were notoriously difficult to repair. It’s important to note that any time there is an increase in voltage, there is a proportionally increased need to contain the voltage with additional insulation. New advances in insulation material technology have made it easier to provide durable, reliable solutions.

Maintenance and cleanliness are a key part of any professional facility. For repair companies, this requires routine inspections for all large industrial motors. Whether it is a simple blow down or inspection, motors need to be cleaned when they get dirty. Routine electrical tests will also indicate cleanliness problems, and the testing data can also be used as part of a predictive maintenance program. Predictive maintenance is especially important for large motors and applications running mission critical operations. Outages can be scheduled in advance, inspections can be conducted onsite before removing equipment for repairs, and emergency disruptions in service can be avoided. Good maintenance is even more important for large voltage motors because the higher the voltage rating, the lower the current rating. While there are significant gains in efficiency, extra measures have to be taken to add more insulation to contain that voltage or pressure.

Q: Please describe the interaction between the footprint of the equipment, the voltage rating, and the horsepower rating?

A: The torque output drives the footprint of the motor. For example, a 100 HP large motor rated for 1,800 RPM produces 300 pound-feet of torque. Almost 1,800 pound-feet of torque is produced when the speed rating changes to 300 RPM with the same 100 HP motor. The added mechanical load requires additional mechanical structure.

Q: Any concluding remarks regarding medium motor repair?

A: The best way to ensure to a long-lasting motor is to carry out routine inspections, regular cleaning, vibration monitoring, and electrical testing.

Wazee Electric, A Timken Brand