Electric motors are everywhere in a factory, from blower fans to the machinery and conveyor belts that move components across production floors. They also account for a large share of industrial energy consumption, making them a major opportunity for energy savings. With energy efficiency regulations likely to get tighter over the coming years, upgrading your industrial electric motors now can pay off in clear cost and energy savings throughout their working lives.
Motors powered by variable speed drives consume significantly less energy than motors that run at constant speed. The savings come from precise electrical control that allows for motor speeds to be revved up, slowed down or sustained indefinitely. It also allows operators to cut out expensive mechanical speed-control components like carbon brushes and gearboxes. Click here or navigate to our official page to discover exclusive offers on used electric motors.
The basic electronic structure of a VSD starts with an input converter that converts incoming 3-phase AC power into DC power using diodes or thyristors. This DC power gets stored in capacitors inside the drive, which helps to smooth out the electrical waveform. Then, this power is processed through an inverter that changes the filtered DC into an output AC waveform that goes to the motor. Using pulse width modulation, the inverter is able to change the voltage and frequency of the output AC power into a waveform that matches the desired motor speed. In the process, this type of drive eliminates the need for a full line voltage to power a motor and also prevents mechanical shock during startup.
It's not uncommon to find that plants have older electric motors for sale whose energy efficiency falls short of modern standards. Upgrading these motors to higher efficiency levels before they reach the end of their service lives typically has a rapid payback period and brings energy savings. Regular maintenance also makes a difference. Keeping voltage close to the nameplate value and ensuring that all three legs of the motor system are equal helps prevent current unbalance, which reduces efficiency, increases operating temperatures, and shortens insulation life. As copper is one of the most expensive components in electric motors, companies are working hard to ensure they are using this material wisely. For instance, research at the Laboratory has developed a way to increase the conductivity of copper wire without increasing its cost – potentially reducing energy losses by 5%. This technology, when fully commercialized, will provide new opportunities for efficiency upgrades to existing motor systems.
In terms of their basic design, electric motors haven't changed much in the 150 years since they were first invented. They still rely on the interaction of magnetic forces generated by permanent magnets and fluctuating fields created by the flow of electricity through coiled copper wire. This system of power transmission produces considerable wasted heat, and the fact that it can only generate a specific amount of torque at a given speed means that motors must often be paired with a reduction gear to utilize their full potential. Fortunately, the same technology that is now powering everything from electric cars to vacuum cleaners can be used to dramatically improve the efficiency of industrial electric motors.
