Practical direct current (DC) motors came to be inside early 19th century following experiments by Michael Faraday and others. DC motors continued to be improved upon along with DC generators to the period of Thomas Edison's first power plant and DC power distribution system in 1882.
This has not been a practical solution to the electrification from the United States Of America however because in the large conductors needed to transmit the reduced voltage power in the power plant on the customer.
George Westinghouse backed Nicolas Tesla's promotion of alternating current (AC) that could be transformed from low voltage to high voltage for efficient long-distance transmission, then back back off to produce homes and industry. AC electrification in the US was the only real practical solution.
Despite the dominance of alternating current today however, both AC and DC motors have practical applications. AC or DC motors have two interacting magnetic fields a minimum of among that is wound and electrified. The other magnetic field can be produced by magnets so it is a permanent magnet motor type.
AC motors generally fall under one of two categories, synchronous or asynchronous types. Synchronous motors synchronize while using frequency of the alternating current whereas asynchronous motors run at the slightly slower speed compared to synchronous speed. The difference in output speed of asynchronous motors compared to synchronous speed is described as slip.
The speed of a synchronous motor is determined by frequency of the AC current along with the number of poles inside motor by the following: Speed in revolutions each minute (rpm) = 120 x frequency (Hz)/ quantity of motor poles.
Asynchronous motors are brushless as are lots of synchronous motor types but some synchronous motors include brushes and a slip ring. Brushless motors by definition may have lower maintenance because the sole parts to wear from friction are the shaft bearings.
Also described as an induction motor, the asynchronous AC motor was invented by Nikola Tesla in 1882 and is considered being one from the 10 greatest discoveries coming from all times. Induction motors are among the most common inside the world powering machinery and lots of applications in the home today including common appliances like refrigerator and air conditioner compressors, washing machines, dryers and fans.
Common samples of synchronous motors are AC electric clocks and timer motors in appliances. A special type of synchronous motor is really a stepper motor. Stepper motors are employed inside a number of open loop motion control applications being a affordable alternative to a brushless servomotor. A brushless servomotor is another form of synchronous motor having permanent magnets and an integrated feedback device that continuously monitors the shaft motion, as well as in combination which has a servo drive regulates the commanded motion very precisely.
DC motors have many applications where DC power is easily available or when duty cycles are low like for vehicle starter motors. Unlike AC motors all DC motors have brushes and a commutator that interact to automatically switch current to various windings in order to result in rotation. DC torque motors are built to provide smooth controllable torque to some load typically below 1000 rpm, and sometimes in just a limited angle of motion. Torque motors could also be of the AC type. Examples include feed or use up rolls on industrial equipment or being an actuator to alter the opening of a valve or move a direct flight ticket surface.
With so many motor types to choose from as well as the tens of a large number of standard models available it could certainly be a challenge to pick the correct one. Fortunately you can find resources like on-line tutorials, motor sizing software, and application engineers who will be happy to supply assistance.
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