Letter In

Instrument Transformer
A type of transformer used to sense the voltage or current
of associated conductors and provide proportional electrical
energy to measurement devices or circuits. A potential
transformer (PT) is used for voltage measurements and a
current transformer (CT) is used for current measurements.


Insulated Case Circuit Breaker A type of circuit breaker that conforms to NEMA AB-1 and
UL 489 standards for molded case circuit breakers and is often
used as a main breaker in switchboards, motor control centers,
or in other applications requiring a molded case circuit breaker
with a high continuous current rating.



Insulated Gate Bipolar Transistor (IGBT) A type of transistor often used as a switching device in the inverter section of a variable frequency drive. Voltage on the gate element is used to control the current flowing between the collector and emitter.