An overview of renewable energy sources, including the wind, wave, hydro, tidal, solar-thermal, geothermal and biomass-thermal, which utilize electric machines for electricity generation is presented; whereas the solar electric (photo voltaic) and thermoelectric power generations which directly produce electricity without using electric machines will not be discussed. Basically, these renewable
Year: 2014
As their name implies, motor starters apply electric power to a motor to begin its operation. They also remove power to stop the motor. Beyond merely switching power on and off, starters include overload protection, as required by the National Electrical Code. The code also usually requires a disconnect and
Rigid base is bolted, welded, or cast on main frame and allows motor to be rigidly mounted on equipment. Resilient base has isolation or resilient rings between motor mounting hubs and base to absorb vibrations and noise. A conductor is imbedded in the ring to complete the circuit for grounding
A brake motor is a pre-connected package of industrial-duty motor and fail safe, stop-and-hold spring-set brake. In case of power failure, the brake sets, holding the load in position. Brake motors are commonly used on hoists or other lifting devices. Brake features can also be added to standard motors through
These motors are always part of integrated motor-and-controller systems that provide extreme accuracy in positioning and speed. Common applications include computer-controlled manufacturing machines and process equipment. Servomotors are the largest category of motors for precision motion control. AC, DC brush-type, and brushless DC versions are available. Closed-loop control systems, common
Polyphase (three-phase) induction motors have a high starting torque, power factor, high efficiency, and low current. They do not use a switch, capacitor, relays, etc., and are suitable for larger commercial and industrial applications. Polyphase induction motors are specified by their electrical design type: A, B, C, D or E, as
Types of single-phase motors are distinguished mostly by the way they are started and the torque they develop. Shaded Pole motors have low starting torque, low cost, low efficiency, and no capacitors. There is no start switch. These motors are used on small direct drive fans and blowers found in
The electric motor in its simplest terms is a converter of electrical energy to useful mechanical energy. The electric motor has played a leading role in the high productivity of modern industry, and it is therefore directly responsible for the high standard of living being enjoyed throughout the industrialized world.
Most differential protection relays are current differential relays in which vector difference between the current entering the winding and current leaving the winding is used for sensing and relay operation. Differential protection principle is used I the following applications. § Protection of the generator, protection of generator transformer unit. §
Differential protection is based on the fact that any fault within electrical equipment would cause the current entering it, to be different, from that leaving it. Thus, we can compare the two currents either in magnitude or in phase or both and issue a trip output if the difference exceeds
