Transmitter. An instrument which originates the signals which are sent through a line or circuit. The Morse key in telegraphy and the Blake transmitter in telephony are examples.
Tri-phase. Three-phase.
Trolley. A contact-wheel of bronze which rolls under the supply-wire in an overhead traction system and takes off the current necessary to run the car motors.
Trolley-wheel. The same as Trolley.
Trolley-wire. The overhead wire in a traction system which feeds the current through a trolley-wheel and pole to the motors of a car running underneath.
True Ohm. (See [Ohm, True].)
True Resistance. (See [Resistance, True].)
Two-wire Circuit. The single system universally used for light and power transmission of current.
U
Undulating Current. (See [Current, Undulating].)