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Glossary Section A-1
IGBT Insulated Gate Bipolar Transistor (IGBT) – A semiconductor transistor
capable of conducting very large currents when in saturation and capable of
withstanding very high voltages when it is OFF. This high-power bipolar tran-
sistor is the type used in Omron inverters.
Inertia The natural resistance a stationary object to being moved by an external
force. See also Momentum.
Intelligent Terminal A configurable input or output logic function on the Omron inverters. Each ter-
minal may be assigned one of several functions.
Inverter A device that electronically changes DC to AC current through an alternating
process of switching the input to the output, inverted and non-inverted. It con-
tains three inverter circuits to generate 3-phase output to the motor.
Isolation Transformer A transformer with 1:1 voltage ratio that provides electrical isolation between
its primary and secondary windings. These are typically used on the power
input side of the device to be protected. An isolation transformer can protect
equipment from a ground fault or other malfunction of nearby equipment, as
well as attenuate harmful harmonics and transients on the input power.
Jogging Operation Usually done manually, a jog command from an operator's panel requests the
motor/drive system to run indefinitely in a particular direction, until the
machine operator ends the jog operation.
Jump Frequency A jump frequency is a point on the inverter output frequency range that you
want the inverter to skip around. This feature may be used to avoid a resonant
frequency, and you can program up to three jump frequencies in the inverter.
Line Reactor A three-phase inductor generally installed in the AC input circuit of an inverter
to minimize harmonics and to limit short-circuit current.
Momentum The physical property of a body in motion that causes it to remain in motion.
In the case of motors, the rotor and attached load are rotating and possesses
angular momentum.
Multi-speed Operation The ability of a motor drive to store preset discrete speed levels for the motor,
and control motor speed according to the currently selected speed preset.
The Omron inverters have 16 preset speeds.
Motor Load In motor terminology, motor load consists of the inertia of the physical mass
that is moved by the motor and the related friction from guiding mechanisms.
See also Inertia.
NEC The National Electric Code is a regulatory document that governs electrical
power and device wiring and installation in the United States.
NEMA The National Electric Manufacturer's Association. NEMA Codes are a pub-
lished series of device ratings standards. Industry uses these to evaluate or
compare the performance of devices made by various manufacturers to a
known standard.
Open-collector Outputs A common logic-type discrete output that uses an NPN transistor that acts as
a switch to a power supply common, usually ground. The transistor's collector
is open for external connection (not connected internally). Thus, the output
sinks external load current to ground.
Power Factor A ratio that expresses a phase difference (timing offset) between current and
voltage supplied by a power source to a load. A perfect power factor = 1.0 (no
phase offset). Power factors less than one cause some energy loss in power
transmission wiring (source to load).
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