H&N Electric Medium Voltage Repair Capabilities

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: Describe an engineering manager’s role at a repair facility, and what are the required qualifications for the position?

A: An engineering manager looks after day-to-day electrical and mechanical engineering operations. I earned a dual degree in electrical and mechanical engineering.

Q: What distinguishes your repair company compare from others in the industry?

A:Our repair company is very active in the EASA community. EASA (Electrical Apparatus Service Association) is a leading provider of specifications and standards for electric motor repair or electrical mechanical equipment. Their website lists over 1,000 service centers in the United States. There are a lot of repair shops in the country, but most motor repair services are local and generally work on small, low voltage rated motors. Our company is the largest electric motor repair shop in the eastern-half of the United States, and we are prepared to repair a wider range of motors and offer a wider range of repair services to our clients.

Q: Please give us some detail regarding medium voltage motor classifications?

A: Motors are classified through voltage ratings., and medium voltage motors range between 1,000 volts and 13,800 volts. 2,300 volts is a common voltage rating for medium voltage motors. For sub-hundred horsepower applications, 240 volt or 480 volt motors are common, but for larger horsepower equipment, lower voltage ratings become cost prohibitive to operate. Switching to higher voltage systems, makes it possible to realize exponential gains in motor efficiency, as long as additional insulation protection is used to contain the voltage.

Q: Are medium voltage motors commonly used for industrial applications?

A: For industrial operations ranging from 200-300 HP, and up to 700 HP, medium voltage motors are the preferred option. The use of sub-600 voltage equipment and equipment that runs on more than 1,000 volts is evenly distributed, but when additional horsepower is required, medium voltage motors provide important advantages. Because of their efficiency, reliability, and savings in operating costs, medium voltage motors are the preferred choice for mission-critical applications.

Q: What criteria do you use when selecting a motor?

A: Motor selection criteria is determined by the specific application requirements. Motors are selected by analyzing the application type and the associated operational details. For example, pumps and fans have particular requirements, and thermal control is a critical factor in compressor design because they are usually highly stressed components. Belt drive applications require motors that can take a substantial amount of radial loading. Other specialized equipment such as centrifuges also require engineering expertise to select the best motor.

Q: Do industries commonly use medium voltage motors in their daily operations?

A: You will find medium voltage motors throughout every major industry across the country, including the petrochemical, pulp and paper, metals manufacturing, and power generation industries. In the mid-20th century, most industries depended more on their location. Industries such as pulp and paper mills would locate near water sources, with less concern for the power infrastructure. Now, new plants will select a location to make the best use of medium voltage motors on the power grid.

Q: Can most motor repair facilities provide repair services for medium voltage motors?

A: No. Most repair services work locally, and there are very few companies equipped to service medium voltage motors. And then there are also repair companies who repair high voltage equipment that is classified at 13,800 volts and higher, but they are also much less common. Our company is capable of conducting all of the necessary electrical tests in the field and troubleshooting breaker systems and transformers. Our highly trained staff is prepared to work on-site or in the machine shop.

In cases where it is not feasible to transport large equipment to the machine shop, specialized onsite large motor repair is available. For medium voltage equipment, a full array of large motor repair or large generator repair services is available in-house. Through our association with the Timken Power Systems’ network, our repair company is able to provide our customers access to the large motor facilities in their network, and an expanded scope of capabilities. While our company focuses primarily on electrical motor repair services, such as servicing the driver, switchgear, and repairing the transformer the Timken Power Systems’ network enables us to repair medium voltage motors and equipment for three-quarters of the eastern United States within eight hours.

Q: What are some of the details regarding your company’s load testing and spin test capabilities?

A: To perform validation testing for medium voltage motors, a facility needs ready access to available power sources, and apply the power source to that particular motor. Our repair company uses a dedicated 2,500 KVA test center, providing ready access to properly calibrated power sources. All of the medium volt classifications can be tested, such as 13,800 volts, 7,200 volts, 4,000 volts, and 2,300 volts. Using a dynamometer with a capacity of 12,000 lb-ft of torque, equates to 2,500 HP at 1,200 RPM, makes it possible to test a 5,000 HP motor with a full complement of documentation at proportional values. Our company’s validation testing capability sets us apart from our competitors.

Q: What are the types of warranties your repair company offers for their repair services and what is your company’s policy regarding maintenance?

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

In the past, we made some short term exceptions for manufacturers involved with random wound equipment in medium voltage, in a 2,300 volt class. The OEMs pushed the design envelope, and some of these motors were often extremely difficult to repair. Any time there is an increase in voltage, there is a proportionally increased need to contain the voltage with additional insulation, and advances in insulation material technology have made it easier to provide a durable and reliable upgrade.

Maintenance and cleanliness are important for any professional facility, and for motor repair companies, this involves the routine inspection of all large industrial motors. Motors need to be cleaned when they get dirty, whether it is a simple blow down or inspection. The routine electrical tests will also reveal cleanliness problems, and the data can also be applied to predictive maintenance. For large motors and applications running mission critical operations, predictive maintenance is especially important because outages can be scheduled in advance, inspections can be carried out onsite before removing equipment for repairs, and emergency interruptions in service can be prevented. Good maintenance becomes even more important for large voltage motors because the higher the voltage rating, the lower the current rating, and additional insulation is needed to contain that voltage or pressure.

H&N Electric is your one-stop shop for industrial motor repair.

H&N Electric is your one stop shop for industrial motor repair or gearbox repair.

Q: What is the specific interaction between the equipment footprint, the voltage rating, and the horsepower rating?

A: Torque output drives the motor footprint. Here’s a common example: a 100 HP large motor rated for 1,800 RPM produces 300 pound-feet of torque. When the speed rating is changed to 300 RPM with the same 100 HP motor, almost 1,800 pound-feet of torque is produced. Additional mechanical structure must be added to take the added mechanical load.

Q: Are there any concluding remarks regarding medium motor repair?

A: The recommended course of action to ensure to a long-lasting motor involves routine inspections, regular cleaning, vibration monitoring, and electrical testing.

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