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Commonly used terms in the Electrical industry.
resonance fluorescence
the modified fluorescence produced when a quantum mechanical system is strongly driven by one or more near-resonant electromagnetic fields.
resonant
in any circuit or system under excitation, the frequency at which a pair of reactive components cancels (pole or zero) resulting in a natural mode of vibration.
resonant antenna
linear antennas that exhibit current and voltage standing wave patterns formed by reflections from the open end of the wire.
resonant frequency
(1) a frequency at which the input impedance of an device is nonreactive, since the capacitive and inductive stored energy cancel each other.
(2) an oscillation frequency of the modes of a resonator.
resonator
circuit element or combination of elements, which may be either lumped or distributed, that exhibit a resonance(s) at one or more frequencies. Generally, a resonant condition coincides with the frequency where the impedance of the circuit element(s) is only resistive.
reverse breakdown
the diode operating region in which significant current flows from cathode to anode, due to an applied voltage exceeding the breakdown voltage.
reverse engineering
the reverse analysis of an old application to conform to a new methodology.
reversing motor starter
a motor controller capable of accelerating a motor from rest to normal speed in either direction of rotation. Some reversing motor starters can go directly from forward to reverse (or vice versa), while others must be stopped before a reversal of direction can take place. Both electromechanical and electronic reversing starters are available.
revolving field
the magnetic field created by flow of a set of balanced three-phase currents through three symmetrically displaced windings. The created field revolves in the air-gap of the machine at an angular velocity corresponding to the synchronous speed of the machine. The revolving field theory is the basis of functioning of synchronous and induction machines.
right hand circular polarization
the state of an electromagnetic wave in which the electric field vector rotates clockwise when viewed in the direction of propagation of the wave.
RMS
root-mean-squared
RMS power
root-mean-squared power
robust control
control of a dynamical system so that the desired performance is maintained despite the presence of uncertainties and modeling inaccuracies.
robust controller design
a class of design procedures leading to control systems that are robust in the sense of required performance. Robust design is a feedback process involving robustness analysis. A specific technique used in robust controller design depends on the type of model describing a system and its uncertainty, control objective, and a set of admissible controllers. The first requirement is to ensure robust stability; this could be followed by guaranteed cost, disturbance rejection, robust poles localization, target sets or tubes reachability, or other demands.
Ackermann's three basic rules of robust controller design are as follows:
1. Require robustness of control system only for physically motivated parameter values and not with respect to arbitrarily assumed uncertainties of the model.
2. When you close a loop with actuator constraints, leave a slow system slow and leave a fast system fast.
3. Be pessimistic in analysis; then, you can afford to be optimistic in design.
rotating excitation system
an excitation system derived from rotating AC or DC machines. The output of the system is still DC and connected to the rotor.
rotating-rectifier exciter
an AC generator, with rotating armature and stationary field, whose output is rectified by a solid-state device located on the same shaft to supply excitation to a larger electrical machine, also connected to the same shaft.
rotational loss
one of several losses in a rotating electric machine that are primarily due to the rotation of the armature and include the friction and windage losses. Also called mechanical loss. They can be determined by running the machine as a motor at its rated speed at no load, assuming the armature resistance is negligible.
rotor
the rotating part of an electrical machine including the shaft, such as the rotating armature of a DC machine or the field of a synchronous machine.
rotor power developed
the amount of power developed by the rotor. In DC machines, the developed power, frequently denoted by Pd , is calculated as the product of the induced EMF Ea and the armature current Ia. In induction machines, the rotor power developed is obtained by subtracting the rotor copper losses from the air gap power.
rotor power loss
represents the portion of the power transferred across the air gap to the rotor of an induction motor that is lost either through ohmic heating of the rotor windings or due to friction and windage losses in the rotor. The mechanical power available at the motor shaft is the difference between rotor power input and rotor power losses.