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Commonly used terms in the Electrical industry.
resistance ground
a grounding scheme in which the neutral of Y-connected machines is connected to ground through a resistance such that ground-fault currents are limited.
resistance grounded
See
low resistance grounded system
,
high-resistance grounded system
low resistance grounded system
an electrical distribution system in which the neutral is intentionally grounded through a low resistance.
Low resistance grounding will limit ground fault current to a value that significantly reduces arcing damage but still permits automatic detection and interruption of the fault current.
resonance
in an RLC circuit, the resonance is the state at which the reactance of the inductor, X
L
, and the reactance of the capacitor, X
C
, are equal.
X
L
= 2πfL
X
C
= 1/(2πfC)
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.