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Electrical Engineering Terms T

Timer

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

Totally Enclosed Fan Cooled (TEFC).

Normally abbreviated to the acronym TEFC, this term describes motor enclosures with the end bells and the cylindrical motor housing sealed to prevent the entrance of moisture or dirt. Often the outer surface of the cylindrical motor housing is molded with external protruding fins to increase the outer surface area of the housing. A fan is normally mounted externally on a jack shaft on the non-drive end of the motor with a protective fan shroud to help cool the motor with this type of enclosure.

Totally Enclosed Nonvented (TENV).

Normally abbreviated to the acronym TENV, this term describes motor enclosures that are designed to be frequently hosed down. These electric motors are generally used in harsh environments such as chemical or food-processing plants.

2-Phase Alternating Current (AC) System / 2-Phase AC Power.

This term refers to the electrical power generation, transformation, transmission, or utilization of two single-phase AC, 2-wire sources that are not interconnected. As compared to the 3-phase alternating current in which three single-phase AC sources are generated simultaneously, 1200 apart, from a common rotating excitation field, and share common circuit conductors (three wires instead of six), this system consists of two single-phase AC sources generated simultaneously, 900 apart, from a common rotating excitation field, but have separate circuit conductors — four total.

2-Phase, 5-Wire AC System.

This term refers to the electrical power generation, transformation, transmission, or utilization of two single-phase AC, 2-wire sources that are interconnected. This 2-phase alternating current supply is comprised of five, instead of four conductors: The four ungrounded phase conductors are the supply and return of each of the two single-phase AC sources. When supplied from two mid-tapped single-phase transformers, the fifth conductor is connected commonly to the neutral points of both phases.

TV-FLC.

Acronym for the NE Code-Table-Value full load current of an electric motor.

Transformer.

A magnetically-operated device or machine that can change values of voltage, current, or impedance in a given electrical circuit without any change in frequency.

Transformer Action.

The relative motion provided by the sinusoidal electromagnetic field of the primary winding in a transformer that induces a voltage in the secondary winding conductor.

Transformer Polarity.

The relationship between the primary and secondary or different windings in a transformer at the same point in time.

Transducer

                     The resistor that changes its value depending on an external force, pressure, temperature, etc.

Thermistor

                    The transducer that changes its value based on minute changes in temperature

Transient Time

The five-time constants or the time to fully charge/discharge a capacitor.

True Power

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

 

About Ahmed 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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