(redirected from transiently)
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 ?
To validate their findings, the investigators also conducted a secondary analysis, examining the risk of typical osteoporotic fractures among women who used bisphosphonates for 5 years or more, compared with women who used the medication transiently.
activity by transiently expressing pro-von Willebrand's facto r (pro-vWF), which is a substrate for PC?
ZetaCrystallin cell lines) were transiently transfected with plasmids encoding for a firefly/Renilla luciferase reporter sequence with or without an inserted glutamine 3' UTR (untranslated region).
Telomerase-positive HT and HL-60 cells were induced to differentiate by retinoic acid (RA) for 1, 3, 6, 9, and 12 days and transiently transfected with hTERT promoter constructs (P-3996, P-1009 and P-330) containing the luciferase gene.
Further, what evidence do you have that increasing T-levels transiently, for no more than one hour, in the mature adult, positively affects either the acquisition of muscle mass or muscle substrate restoration?
After eliminating several possible explanations for the change in the protein, they concluded that a large percentage of the losses occurred because the protein transiently adsorbed, or stuck, to the silicone rubber tubing in the catheter.
Initially beneficial, this massive inflammatory response comes with a cost, and adult injured tissues usually heal with a scar, which is an area of fibrous tissue that transiently replaces normal tissue.
The CDC website transiently acknowledged the danger of transmission by aerosol, but this material was quickly removed.
We found one part of plasminogen seems to be very unstable and transiently opens up a tiny bit.
Summary: TEHRAN (FNA)- A major downside of the medical use of marijuana is the drug's ill effects on working memory, the ability to transiently hold and process information for reasoning, comprehension and learning.
Introduction of iodised salt to regions of chronic iodine-deficiency disorders might transiently increase the proportion of thyroid disorders, but overall the small risks of iodine excess are far outweighed by the substantial risks of iodine deficiency.