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is the torque produced divided by armature current. [10] It can be calculated from the motor velocity constant . = = = where is the armature current of the machine (SI unit: ampere).
The field produced by a single-phase winding can provide energy to a motor already rotating, but without auxiliary mechanisms the motor will not accelerate from a stop. A rotating magnetic field of steady amplitude requires that all three phase currents be equal in magnitude, and accurately displaced one-third of a cycle in phase.
A three-phase induction motor has a simple design, inherently high starting torque and high efficiency. Such motors are applied in industry for many applications. A three-phase motor is more compact and less costly than a single-phase motor of the same voltage class and rating, and single-phase AC motors above 10 hp (7.5 kW) are uncommon. Three ...
Inrush current can also be reduced by inrush current limiters. Negative-temperature-coefficient (NTC) thermistors are commonly used in switching power supplies, motor drives and audio equipment to prevent damage caused by inrush current. A thermistor is a thermally-sensitive resistor with a resistance that changes significantly and predictably ...
One typical 12 V motor vehicle headlight (typically 60 W) 9A 230 V AC, toaster, kettle (2 kW) 10 1: 10 or 20A 230 V AC, Europe common domestic circuit breaker rating 15 or 20A 120 V AC, United States, Canada and Mexico domestic circuit breaker rating 16.6A 120 V AC, toaster, kettle (2 kW) 20A 230 V AC, Immersion heater (4.6 kW) 24A
In electromagnetism, current density is the amount of charge per unit time that flows through a unit area of a chosen cross section. [1] The current density vector is defined as a vector whose magnitude is the electric current per cross-sectional area at a given point in space, its direction being that of the motion of the positive charges at this point.
[4]: 15 Electric current is also known as amperage and is measured using a device called an ammeter. [ 2 ] : 788 Electric currents create magnetic fields , which are used in motors, generators, inductors , and transformers .
Angle notation can easily describe leading and lagging current: . [1] In this equation, the value of theta is the important factor for leading and lagging current. As mentioned in the introduction above, leading or lagging current represents a time shift between the current and voltage sine curves, which is represented by the angle by which the curve is ahead or behind of where it would be ...