Charlie Sheen's Guide To Trigger

Motor

It includes a rotor spinning with coils passing magnets at the same frequency as the AC and produces a magnetic field to drive it. One type of synchronous motor is like an induction motor except that the rotor is excited by a DC field. The rotor poles connect to each other and move at the same speed. Another type, for low load torque, has flats ground onto a conventional squirrel-cage rotor to create discrete poles.

The largest are used for ship propulsion, pipeline compression and pumped-storage applications with output exceeding 100 megawatts. With only a few moving parts, AC motors have the potential to last for years. The durability of AC motors makes them a preferred solution for field applications such as agricultural equipment and commercial applications such as vending machines.

The application of the electric motor tends to influence whether AC or DC is selected. The key is that as the rotor passes through the horizontal position, the poles of the electromagnet flip. Because of the flip, the north pole of the electromagnet is always above the axle so it can repel the stator's north pole and attract the stator's south pole. The diagram shows how the commutator and brushes work together to let current flow to the electromagnet, and also to flip the direction that the electrons are flowing at just the right moment.

The commutator periodically reverses the current direction in the rotor windings with each half turn (180°), so the torque applied to the rotor is always in the same direction. Without this current reversal, the direction of torque on each rotor winding would reverse with each half turn, so the rotor would stop. Commutators are inefficient and commutated Motors have been mostly replaced by brushless direct current motors, permanent magnet motors, and induction motors.

Electric machines come in salient- and nonsalient-pole configurations. In a nonsalient-pole (or distributed field or round-rotor) motor, the ferromagnetic core is a smooth cylinder, with the windings distributed evenly in slots about the circumference. Supplying alternating current in the windings creates poles in the core that rotate continuously. A shaded-pole motor has a winding around part of the pole that delays the phase of the magnetic field for that pole. The rotor is the moving part that delivers the mechanical power. The rotor typically holds conductors that carry currents, which the magnetic field of the stator exerts force on to turn the shaft.

Motor losses are mainly due to resistive losses in windings, core losses and mechanical losses in bearings, and aerodynamic losses, particularly where cooling fans are present, also occur. The most general approaches to calculating the forces in motors use tensor notation. High starting currentLower efficiency due to need for magnetization. Stepper motors are often used in computer printers, optical scanners, and digital photocopiers to move the active element, the print head carriage , and the platen or feed rollers. BLDC motors do not spark, making them better suited to environments with volatile chemicals and fuels. Sparking also generates ozone, which can accumulate in poorly ventilated buildings.

The rotor speed is less than the speed of the field by an amount that is just enough to induce the required voltage in the rotor conductors to produce the rotor current needed for the load torque. At full load, the speed is typically 0.5 to 5 percent lower than the field speed , with the higher percentage applying to smaller motors. A majority of three-phase induction motors operate with their stator windings connected directly to a three-phase electric supply of constant voltage and constant frequency.