In 2000, National Oilwell, now known as National Oilwell Varco, established itself as a major manufacturer of industrial electric motors and generators when it purchased the Baylor Co. of Sugar Land, Texas. Ironically, prior to 1982 the Oilwell Division of U.S. Steel Corp., one of several large manufacturers of oil well drilling rigs, manufactured Baylor eddy current auxiliary brakes for draw works on its rigs. But after merging with National Supply during an oil market bust, it spun off the Baylor product line to an investor group.

Today, National Oilwell Varco manufactures a complete line of Baylor ac generators from 50 to 15,000 kW for voltages from 208 to 13,800 V and for speeds from 600 to 1800 rpm. The company said that over 10,000 Baylor generators have been applied worldwide, dating back to 1979. However, the product line's heritage dates all the way back to the first Delco ac generator that entered service in 1939, many of which remain in service yet today.

"We remain a strong player in the ac generator market, and about 40% of our business is still involved in manufacturing and rebuilding eddy current auxiliary brakes for drilling rigs. But our biggest emphasis today is on our Baylor and Louis Allis brands of electric motors from 400 to 15,000 hp," explained Thomas G. Purtill, vice president--sales for National Oilwell Varco's Power Solutions Group.

"Custom-designed and engineered motors for unique applications are our specialty," said Roger Case, motor sales manager. National Oilwell Varco motors are applied in various markets that include water pumping--both clean and waste water, utilities, refineries, pulp and paper, mining, metal working, chemical processing, military, marine and both centrifugal and reciprocating compressor drives.

"We are seeing a swing of our motor business to more compressor drive applications, as customers are finding that our synchronous motors are an especially good fit for reciprocating compressors," explained Case.

National Oilwell Varco's large synchronous motor product line ranges from 1000 to 15,000 hp and speeds from 200 through 1800 rpm. Its induction motor line covers the range from 400 to 15,000 hp. Both the synchronous and induction products are available from 460 to 13,800 V with indoor or outdoor enclosures and horizontal or vertical mountings. They are compatible with variable frequency drives (VFD) and soft starters.

"We've been at the Sugar Land facility for 30 years and we're one of the few totally US. A-manufactured motors," added Case. The 76,201 sq.ft. Sugar Land works is indeed a completely integrated motor and generator manufacturing facility. In addition to engineering, assembly and testing of the machines, all major motor and generator components except bearings are manufactured there.

"We emphasize total cost of ownership and being an active part of the customer's team. We strive to meet or exceed our customer's expectations all the time," said Greg P. Cervenka, chief engineer. The company uses computer-aided drafting, along with structural, modal and finite element analysis for design and manufacturing. "These advanced design techniques contribute to such benefits as size and weight reduction and air-flow improvements that keep motor operating temperatures low and efficiencies high," he added. CNC machine tools are used to maintain the tight tolerances needed for precision fits, runouts and air gaps.

Standard features of National Oilwell Varco motors include integral, nonprotruding mounting pads to accommodate doweling and jacking in each pad; computer-designed fabricated steel housings to resist vibration; coatings for corrosion resistance; rigidly braced end coils to resist vibration yet accommodate thermal expansion under full load; and split bearing brackets. Also included are a uniquely designed mica/glass insulation system that is vacuum impregnated with 100% solids resin and finished with a resin finish treatment; oil level sight glasses for all sleeve bearings; spacious, diagonally split conduit boxes for ease of wiring; and corrosion protection that is appropriate for the application atmosphere.

Available enclosure types include drip proof (DP), weather protected II (WPII), totally enclosed air-to-air cooled (TEAAC), totally enclosed air-to-water cooled (TEWAC), totally enclosed fan cooled (TEFC), and other options to meet special requirements. Specially designed motor case openings minimize the entry of foreign matter, while facilitating cooling air flow to internal electrical parts to improve motor life and performance.

Popular accessories include stator resistance temperature detectors (RTDs), proximity probes for shaft vibration measurement, surge capacitors, bearing RTDs, noise reduction packages, lightning arrestors, sealed insulation and differential current transformers.

The form-wound stator laminations are made of thin sheets of low-loss, high-grade silicon steel. High-strength steel vent spacers, integral to the stator cores, create core vents through which cooling air removes generated heat. The laminations and vent spacers are stacked, compressed under high pressure and then secured in a manner that reduces electrically generated noise and vibration.