The use of motor current signature analysis (MCSA) for motor fault detection — such as a broken rotor bar — is now well established. However, detection of mechanical faults related to the driven system remains a more challenging task. Recently there has been a growing interest for detection of gear faults by MCSA. Advantages and drawbacks of these MCSA-type techniques are presented and discussed on a few industrial cases.

The motors might be small, but the big-brain technology driving these electrical wonders was on full display at the 2014 Small Motor & Motion Association Fall Technical Conference, convened November 4-6 in St. Louis, MO. SMMA, the manufacturing trade association (120 members strong) that tends to the best interests of the electric motor and motion control industries — including manufacturers, suppliers, users, consultants and universities — played gracious host to a wide array of presenters from an equally diverse range of sources — from academia to the federal government. Like gears, motors are most everywhere, as evidenced by SMMA’s membership (consumer-, public interest-, national defense- and commercial-oriented) demographic which includes: appliance; transportation; medical equipment; office automation and computers; aerospace; and industrial automation. The association’s mission: To “serve as the principal voice of the electric motors and drives industry” and to provide a forum to “develop, collect and disseminate technical and management knowledge.”

According to the Department of Energy (DOE), more than half of all electrical energy consumed in the U.S. is used by electric motors. To address this, several years ago, the DOE conducted a technical study as to what could be done to raise the efficiency levels of “small” motors. After years of study and litigation, the Small Motor Rule (SMR) was passed that covers two-digit NEMA frame single- and three-phase ¼ through 3 horsepower motors in open enclosures.

Electric motor-driven systems are the single largest enduser of electricity, accounting for over 40% of global consumption according to the International Energy Agency.

University lab's motor eliminates pricey rare-earth magnets.

There are three major types of reluctance motors: all three reluctance motors are non-permanent magnet, brushless motors. They are synchronous motors with a non-linear relationship between torque and current. The variable-reluctance step and switched-reluctance motors utilize the principle of magnetic attraction by inducing magnet poles within the soft-iron rotor, and by energizing a set of coils wound around stator teeth resident in the laminated stator. These two reluctance motors must be sequentially excited to achieve continuous, steady-state rotation. The design of all reluctance motors requires finite element analysis (FEA) software.

There are more brushless PM motors being made every day. These brushless PM motors are smaller in size -- i.e., less than 50 watts in power output found in hard-disk drives, CD and DVD players and many portable medical devices. Servo systems with brushless PM motors ranging from 50 watts to 50 kilowatts are now challenging the larger electric motor applications. A few manufacturers have pushed brushless PM motors above 200 kW.

Step motors come in many sizes and shapes. But they all share one item in common - each step motor type moves in discrete-degree steps. They react to a series of voltage pulses supplied by their basic controller, known as an "indexer." The step motor was the first to accept digital pulses, then move or rotate a prescribed amount without any feedback device. All step motors are position devices without the need to use any feedback devices. They operate primarily in an open-loop control scheme.

When I woke up this morning, my house was a comfortable 68°F, despite the fact that overnight temperatures in the Chicago area were close to freezing. I don’t often think about the blower motor that helps circulate the warm air from my furnace throughout my house, but today I was grateful for it...

This product focus highlights the latest technology in electric motors.