Letter Tr

Transformer

Coils of wire wound on a common frame that allow electrical
energy to be transferred from one circuit to another.
Transformers used in low frequency applications are commonly
wound around an iron core to improve energy transfer.

Transistor

A semiconductor device which usually has three terminals
although the names of the terminals are different for different
types of transistors. Some types of transistors are used as
electronic switches.

Trim
The front cover of a panelboard which includes an access door.

Trip Unit

The part of the circuit breaker that determines when the
breaker will trip. Many circuit breakers use a thermal-magnetic
or magnetic-only trip unit. Other circuit breakers have a solidstate
trip unit with multiple adjustments to custom fit the circuit
breaker’s time current curve to the application.

True Power

Also called real power, true power is the power dissipated by
circuit resistance. True power is equal to I2R and is measured in
watts. True power is also equal to the apparent power multiplied
by the power factor.