variable speed electric motor

Some of the improvements attained by EVER-POWER drives in energy efficiency, productivity and procedure control are truly remarkable. For example:
The savings are worth about $110,000 a year and have cut the company’s annual carbon footprint by 500 metric tons.
EVER-POWER medium-voltage drive systems allow sugar cane plants throughout Central America to be self-sufficient producers of electrical energy and boost their revenues by as much as $1 million a calendar year by selling surplus power to the local grid.
Pumps operated with adjustable and higher speed electric motors provide numerous benefits such as greater range of flow and head, higher head from an individual stage, valve elimination, and energy saving. To accomplish these benefits, nevertheless, extra care must be taken in choosing the appropriate system of pump, motor, and electronic engine driver for optimum interaction with the procedure system. Successful pump selection requires knowledge of the complete anticipated selection of heads, flows, and specific gravities. Engine selection requires suitable thermal derating and, sometimes, a complementing of the motor’s electrical characteristic to the VFD. Despite these extra design considerations, variable velocity pumping is becoming well accepted and widespread. In a straightforward manner, a discussion is presented on how to identify the huge benefits that variable speed offers and how to select parts for trouble free, reliable operation.
The first stage of a Variable Frequency AC Drive, or VFD, is the Converter. The converter is definitely comprised of six diodes, which act like check valves found in plumbing systems. They allow current to flow in only one direction; the direction shown by the arrow in the diode symbol. For example, whenever A-stage voltage (voltage is similar to pressure in plumbing systems) is usually more positive than B or C phase voltages, then that diode will open up and invite current to stream. When B-phase turns into more positive than A-phase, then the B-phase diode will open up and the Variable Speed Electric Motor A-phase diode will close. The same holds true for the 3 diodes on the negative side of the bus. Thus, we get six current “pulses” as each diode opens and closes.
We can get rid of the AC ripple on the DC bus by adding a capacitor. A capacitor functions in a similar style to a reservoir or accumulator in a plumbing program. This capacitor absorbs the ac ripple and provides a simple dc voltage. The AC ripple on the DC bus is normally less than 3 Volts. Therefore, the voltage on the DC bus turns into “around” 650VDC. The real voltage will depend on the voltage level of the AC range feeding the drive, the amount of voltage unbalance on the energy system, the electric motor load, the impedance of the power system, and any reactors or harmonic filters on the drive.
The diode bridge converter that converts AC-to-DC, may also be just known as a converter. The converter that converts the dc back again to ac can be a converter, but to distinguish it from the diode converter, it is generally referred to as an “inverter”.

In fact, drives are a fundamental element of much larger EVER-POWER power and automation offerings that help customers use electricity effectively and increase productivity in energy-intensive industries like cement, metals, mining, oil and gas, power generation, and pulp and paper.

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