(redirected from transiency)
Also found in: Dictionary, Thesaurus, Medical, Legal.


Physics a brief change in the state of a system, such as a sudden short-lived oscillation in the current flowing through a circuit



(or transient phenomenon). A transient in an electric circuit is a phenomenon that occurs during a transition from one circuit condition to another that differs from the initial condition in the amplitude, phase, shape, or frequency of the voltage acting in the circuit, the values of the parameters, or the configuration of the circuit. Transients occur chiefly when circuit elements are switched into or out of the circuit. The transients arise because the current flowing through an inductance and the voltage across a capacitance cannot be altered abruptly—that is, the energy of the electric and magnetic fields in the circuit’s capacitive and inductive elements cannot be changed instantaneously.

Theoretically speaking, a transient continues for an indefinite period because the voltage and current in an electric circuit after the closing or opening of a switch approach their final (steady-state) values asymptotically. In electrical engineering, however, a transient is considered to be ended when the voltage and current reach values differing from the steady-state values by 5 to 10 percent, a condition that occurs within a comparatively short finite interval of time. An electric circuit that is characterized by constant or periodically varying currents and voltages is said to be in a steady-state condition.

A simple example of a transient is the charging of a capacitor C (Figure 1) from a DC source (a storage battery) having an electromotive force (emf) E and an internal resistance r through a resistor R, which limits the current in the circuit. If the switch is closed at the time t = 0, the current in the circuit decreases according to an exponential law and approaches zero. Simultaneously, the voltage increases and approaches asymptotically the value of the source emf. The rate of change of the voltage and the current depend on the capacitance of the capacitor and the resistance in the circuit: the larger the capacitance and resistance, the longer the duration of the charging process. After a time interval τ = (R + r)C, called the time constant for the charging of the capacitor, the voltage across the capacitor’s plates attains the value uc = 0.6327, and the current i reaches 0.37I0, where I0 is the initial current. I0 is equal to the ratio of the emf and the resistance in the circuit. After a time interval of 5τ;, UC > 0.99E and i < 0.01I0; with an error of less than 1 percent, the transient can be regarded as having ended. During the transient, the energy of the capacitor’s electric field is increased from zero to Wc = CE2/2.

During a transient, in individual parts of a circuit there may occur voltage surges and overcurrents—that is, voltages and currents substantially greater than the steady-state voltages and currents. When equipment is not selected properly, the voltage surges can result in the breakdown of insulation in, for example, capacitors, transformers, and electrical machines. Overcurrents can cause the actuation of protective devices and the disconnection of equipment; they can burn out instruments, burn contacts, and cause mechanical damage to windings as a result of electro-dynamic stresses. Transients play an exceptionally important role in automatic control systems, pulse engineering, computer technology, measurement technology, electronics, radio engineering, and power engineering.


Osnovy teorii tsepei. Moscow-Leningrad, 1965.
Neiman, L. R., and K. S. Demirchian. Teoreticheskie osnovy elektrotekhniki, vol. 1. Leningrad, 1967.
Ginzburg, S. G. Metody resheniia zadach po perekhodnym protsessam ν elektricheskikh tsepiakh, 3rd ed. Moscow, 1967.
Venikov, V. A. Perekhodnye elektromekhanicheskie protsessy ν elektricheskikh sistemakh. Moscow, 1970.
Teoreticheskie osnovy elektrotekhniki, part 1. Moscow, 1972.
Bessonov, L. A. Teoreticheskie osnovy elektrotekhniki. Moscow, 1973.



A pulse, damped oscillation, or other temporary phenomenon occurring in a system prior to reaching a steady-state condition.


1. <electronics> A sudden, brief increase in current or voltage in a circuit that can damage sensitive components and instruments.


A malfunction that occurs at random intervals and lasts for a short duration such as a spike or surge in a power line or a memory cell that intermittently fails. See spike and power surge.
References in periodicals archive ?
And that transition contrasts with Ruth's habit of stitching actual moments together with speculative transitions, as if she were figuratively combining housekeeping with transiency, an ordering narrative impulse with hypothetical meanderings.
Indeed, findings from this study indicated that the effectual relationship between Aboriginal transiency and mainstream education is perhaps one of the most contentious points of public discourse in the region.
Christ is not in creation like a perfecting element, since, as a Person, he towers high above all creaturely perfection" (Tavard, Transiency and Permanence 204).
Although the labor system of the South produced hoboes like Joe and Lucas, transiency was blamed on character.
I am not so dazzled by the autoekphrastic aspect of the Rubaiyat as to deny that this couplet and others like it operate as metaphors for that disenchanted passivity which Fitz-Omar's keen sense of human transiency famously evokes.
The 1937-38 depression might also have confirmed for many the transiency of the recovery, thereby reinforcing their uncertainties about the future, especially about the durability of any recovery.
In The Greatest Generation, Lindenmeyer examines child labor, political agitation for children's rights, juvenile health, poverty, play, popular culture, schooling, transiency, and federal efforts to bring relief to children suffering from physical maladies.
Instead, to fully understand the degree to which Japanese Canadians were uprooted during the 1940s, the term "relocation" or "removal" should be used to represent a period of time when they were internally displaced persons, characterized by a legally restricted lifestyle and high degree of nation-wide transiency that lasted until the early 1950s.
Transiency, vulnerability [Verganglichkeit, Gebrechlichkeit] is the character of a nature bound up with spirit.
Student transiency contributed to the difficulty; however, the main difficulty was that some students were tested in Spanish on the Aprenda in fourth grade and subsequently on the Stanford Achievement Test (SAT) in fifth grade.
The masterpiece--the work, that is, whose value is eternal--embraces the hope of the artist to find something greater than transiency, finitude and death.