Motors and generators
Get flash to fully experience Pearltrees
From Electrical Installation Guide Current demand The full-load current Ia supplied to the motor is given by the following formulae:
Three-phase totally enclosed fan-cooled (TEFC) induction motor, with and, at right, without end cover to show cooling fan. In TEFC motor, interior losses are dissipated indirectly through enclosure fins mostly by forced air convection. An induction or asynchronous motor is an AC motor in which all electromagnetic energy is transferred by inductive coupling from a primary winding to a secondary winding, the two windings being separated by an air gap.
A synchronous motor-generator set for AC to DC conversion.
Electromagnetic induction is the production of a potential difference (voltage) across a conductor when it is exposed to a varying magnetic field .
To understand how an electric motor works, the key is to understand how the electromagnet works. (See How Electromagnets Work for complete details.) An electromagnet is the basis of an electric motor. You can understand how things work in the motor by imagining the following scenario.
An electromagnet is a type of magnet in which the magnetic field is produced by the flow of electric current . The magnetic field disappears when the current is turned off. Electromagnets are widely used as components of other electrical devices, such as motors , generators , relays , loudspeakers , hard disks , MRI machines , scientific instruments, and magnetic separation equipment, as well as being employed as industrial lifting electromagnets for picking up and moving heavy iron objects like scrap iron. A simple electromagnet consisting of a coil of insulated wire wrapped around an iron core. The strength of magnetic field generated is proportional to the amount of current.
U.S. NRC image of a modern steam turbine generator In electricity generation , an electric generator is a device that converts mechanical energy to electrical energy . A generator forces electric current to flow through an external circuit . The source of mechanical energy may be a reciprocating or turbine steam engine , water falling through a turbine or waterwheel , an internal combustion engine , a wind turbine , a hand crank , compressed air , or any other source of mechanical energy.
An induction generator or asynchronous generator is a type of AC electrical generator that uses the principles of induction motors to produce power. Induction generators operate by mechanically turning their rotor faster than the synchronous speed, giving negative slip. A regular AC asynchronous motor usually can be used as a generator, without any internal modifications. Induction generators are useful in applications such as minihydro power plants, wind turbines, or in reducing high-pressure gas streams to lower pressure, because they can recover energy with relatively simple controls.
An engine or motor is a machine designed to convert energy into useful mechanical motion . [ 1 ] [ 2 ] Heat engines , including internal combustion engines and external combustion engines (such as steam engines ) burn a fuel to create heat , which then creates motion. Electric motors convert electrical energy into mechanical motion, pneumatic motors use compressed air and others—such as clockwork motors in wind-up toys —use elastic energy . In biological systems, molecular motors , like myosins in muscles , use chemical energy to create motion. [ edit ] Terminology Originally, an engine was a mechanical device that converted force into motion.
A small, electrically powered pump A pump is a device that moves fluids ( liquids or gases ), or sometimes slurries , by mechanical action. Pumps can be classified into three major groups according to the method they use to move the fluid: direct lift , displacement , and gravity pumps. [ 1 ]
Torque , moment or moment of force (see the terminology below), is the tendency of a force to rotate an object about an axis, [ 1 ] fulcrum , or pivot.
A DC armature. In electrical engineering , an armature generally refers to one of the two principal electrical components of an electromechanical machine – generally in a motor or generator , but it may also mean the pole piece of a permanent magnet or electromagnet , or the moving iron part of a solenoid or relay . The other component is the field winding or field magnet .
An alternator is an electromechanical device that converts mechanical energy to electrical energy in the form of alternating current . Most alternators use a rotating magnetic field with a stationary armature but occasionally, a rotating armature is used with a stationary magnetic field; or a linear alternator is used.
Rotor (lower left) and stator (upper right) of an electric motor Stator of a 3-phase AC-motor Stator of a brushless DC motor from computer cooler fan. The stator is the stationary part of a rotary (electric) system or a Civil defense siren, found in an electric generator , electric motor , siren , or biological rotors . [ edit ] In motors Depending on the configuration of a spinning electromotive device the stator may act as the field magnet , interacting with the armature to create motion, or it may act as the armature , receiving its influence from moving field coils on the rotor .
Electric motors, generators, alternators and loudspeakers are explained using animations and schematics. This is a resource page from Physclips , a multi-level multimedia introduction to physics ( download the animations on this page ). DC motors A simple DC motor has a coil of wire that can rotate in a magnetic field. The current in the coil is supplied via two brushes that make moving contact with a split ring.