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Electric motor-driven systems
are the single largest enduser
of electricity, accounting
for over 40% of global consumption
according to the International
Energy Agency.
If you read only one article this issue, it should
be Norm Parker’s article on the Chinese bearing
manufacturing industry. Parker is an engineer
with General Motors, a true industry insider who has become
a regular contributor to Power Transmission Engineering.
The Formula Renault 3.5 is seen as a crucial stepping stone on the way into the premier class, the Formula 1. Ambitious racers do not just bring their talents - they also have highly efficient motors on board to control the throttle of their 530-hp V8 engines.
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...
Bearings that show wear may not always need to be replaced. Depending on the degree and type of wear, they may be candidates for reconditioning, a process that restores bearings to like-new specifications and performance - at an average 50 to 60 percent of the cost of replacement.