Search results
Results from the WOW.Com Content Network
Now, if this motor is fed with current of 2 A and assuming that back-EMF is exactly 2 V, it is rotating at 7200 rpm and the mechanical power is 4 W, and the force on rotor is = N or 0.0053 N. The torque on shaft is 0.0053 N⋅m at 2 A because of the assumed radius of the rotor (exactly 1 m).
The power factor in a single-phase circuit (or balanced three-phase circuit) can be measured with the wattmeter-ammeter-voltmeter method, where the power in watts is divided by the product of measured voltage and current. The power factor of a balanced polyphase circuit is the same as that of any phase. The power factor of an unbalanced ...
The minimum at unity power factor () is due to the general formula for the power P of a synchronous motor, = . In order to keep the power constant, with the line voltage at the terminals of the armature V A {\displaystyle V_{A}} also constant, any decrease in power factor has to be accommodated by a corresponding increase in the armature ...
Many useful motor relationships between time, current, voltage, speed, power factor, and torque can be obtained from analysis of the Steinmetz equivalent circuit (also termed T-equivalent circuit or IEEE recommended equivalent circuit), a mathematical model used to describe how an induction motor's electrical input is transformed into useful ...
An industrial electric motor . An electric motor is a machine that converts electrical energy into mechanical energy.Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate force in the form of torque applied on the motor's shaft.
Since most power systems of any significant size have a net lagging power factor, the presence of overexcited synchronous motors moves the system's net power factor closer to unity, improving efficiency. Such power-factor correction is usually a side effect of motors already present in the system to provide mechanical work, although motors can ...
For electrical motors, a similar kind of information is conveyed by the service factor, which is a multiplier that, when applied to the rated output power, gives the power level a motor can sustain for shorter periods of time. The service factor is typically in the 1.15-1.4 range, with the figure being lower for higher-power motors.
Synchronous motors are valued in any case because their power factor is much better than that of induction motors, making them preferred for very high power applications. Some of the largest AC motors are pumped-storage hydroelectricity generators that are operated as synchronous motors to pump water to a reservoir at a higher elevation for ...