Time Invariance 

In time invariant system, there are no changes in system structure as a function of a time t.


The SI unit of magnetic flux density; equal to 1 Weber per square meter.

Time Constant

In a capacitor, the time required for a voltage to reach to 63.2 % of the steady-state or full-charge values.

in an inductor, the time required for a current to reach 63.2 % of full or steady-state value.

Thevenin’s Theorem 

Thevenin’s Theorem states that any network having two open terminals can be replaced by a single voltage source VTH in series with a single resistance RTH. Voltage VTH drives any load connected across these terminals with RTH in series.

Twin-Lead Transmission Line

A type of transmission line comprised of two parallel conductors covered by a solid insulator.

Terminal characteristics

A plot of the terminal voltage versus the load current.

Three-phase transformer

A transformer consisting of three pairs of windings used to transform a set of three-phase voltages from one voltage level to another.

Turns ratio

The ratio of the primary winding turns to the secondary winding turns.

Tachometer or Tach

 Test equipment designed to measure the speed of things like shafts that are rotating. The rotating speed is usually reported as RPMs, Revolutions per Minute.

True power

The power lost or dissipated in a circuit typically as heat.


A relay that will delay the switching of the contacts by a predetermined time.

About Ahmad Faizan

Mr. Ahmed Faizan Sheikh, M.Sc. (USA), Research Fellow (USA), a member of IEEE & CIGRE, is a Fulbright Alumnus and earned his Master’s Degree in Electrical and Power Engineering from Kansas State University, USA.

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