Dictionary of Electrical Engineering

Commonly used terms in the Electrical industry.

watt
unit of power in the SI system of units.
Watt
Watt, James (1736-1819) Born: Greenock, Scotland, U.K.

is best known for his work in the development of efficient steam power. Watt began his career as an instrument maker.
When asked to fix a troublesome Newcomen engine, he began to make improvements.

Watt eventually partnered with industrialist Matthew Boulton to form a steam engine company. Watt is credited with having devised the horsepower system. The unit of power, the watt, is named in his honor.
watt-VAR meter
meter capable of simultaneously measuring the real and reactive power delivered to an AC load.
wattmeter
an instrument for measuring electric power in watts. A wattmeter requires connections to measure both the current through and the voltage across the load being measured.
Westinghouse
Westinghouse, George (1846-1914) Born: Central Bridge, New York, U.S.A.

is best known as a financier and industrialist during America's age of great commercial expansion. What is less
known today is that Westinghouse's fortune was based on his early inventions in the railroad industry. His braking system was eventually adopted in most rail cars. Westinghouse went on to secure over 400 patents in the rail and the gas distribution industries. Before hiring Tesla and buying his patents, Westinghouse had been a champion of alternating current for power distribution. His company provided illumination for the great Chicago Exposition of 1893. Before
his death, Westinghouse was to lose control of the companies that bear his name. Undaunted, he returned to the laboratory for a number of additional years of invention.
Wheatstone bridge
a bridge circuit where all arms are resistors. The condition of balance in the circuit is used for precise measurement of resisors. In this case, one of the arms is an unknown resistor, another arm is a standard resistor (usually a variable resistor box), and two other arms (called ratio arms) are variable resistors with a well determined ratio. When the condition of balance is achieved, one can calculate the unknown resistor multiplying the standard resistor value by the ratio of ratio arms resistors. The precision of measurements is 0.05% for the range 10 ohms to 1 megohm.

The Wheatstone bridge is used for resistor measurements at DC and AC (in the universal impedance bridges).

Moreover, the Wheatstone bridge is widely used in resistive transducers where one or more arms is substituted by resistors
the resistance of which depends on a physical variable (temperature, pressure, force, etc.). In these applications, the deflection from balance is used for measurement of the physical variable.
wind-electric conversion
the process by which wind (mechanical) energy is converted to electrical energy, usually by the use of wind turbine.
wind power generator
a system that utilizes the energy in the wind to generate electricity. The energy in the wind drives a wind turbine which acts as the prime mover for the generator. A wind turbine operates at a variable speed, and an appropriate electric machine and controller converts the mechanical energy into electrical energy and pumps it into a utility grid.
winding factor
a design parameter for electric machines that is the product of the pitch factor and the distribution factor.
wiped joint
a fused joint used in splicing lead-sheathed cables.
withstand test
a test of an insulator's ability to withstand a high voltage of some specified waveform.
wound rotor induction motor
an induction motor in which the secondary circuit consists of a polyphase winding or coils connected through a suitable circuit. When provided with slip rings, the term slip-ring induction motor is used.
written-pole motor
a single-phase motor that uses a coil to write poles on the magnetic rotor. The advantage of the written-pole motor is that it draws much lower starting current, allowing much larger single-phase motors. The development of this motor has been sponsored by the Electric Power Research Institute.
wye connection

See Y connection
wye-connection
a three phase source or load connected in the form of Y.
wye-delta starter
a motor starter that starts a three-phase AC motor in wye or star configuration so that the motor starts on approximately 58% of normal voltage, with a two-thirds reduction in starting current. As the motor approaches operating speed, the windings are reconfigured in delta configuration so that full voltage is applied for normal operation. The transition from star to delta is performed with the help of timer settings and contactors.
wye-delta transformer
a connection of a three-phase transformer with one primary and one secondary which can be considered as three similar single-phase transformers. The primary is connected in wye, that is one terminal from each phase is connected to neutral and one to a line voltage. The secondary is connected in delta, with each phase connected between two line voltages.
wye-wye transformer
a three-phase transformer with both the primary and secondary coils connected in wye. This connection is considered undesirable, due to the triple harmonics in the exciting current. To maintain balance load voltages under varying loads, it is necessary to solidly connect the primary and secondary neutrals to ground. This may allow some secondary current to flow on the primary neutral and may also cause interference with parallel communication lines.
wye-wye-delta transformer
a three-phase transformer in which the primary and secondary coils are connected in wye. In order to overcome the problems with the wyewye connection, a set of tertiary coils are connected in delta to provide a path for the triple harmonic components of the exciting current to circulate.
X-ray lithography
lithography using light of a wavelength in the range of about 0.1 to 5 nm, with about 1 nm being the most common, usually taking the form of proximity printing.
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