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Appendix A
Glossary and Bibliography
A-1 Glossary
Ambient Temperature The air temperature in the chamber containing a powered electronic unit. A
unit's heat sinks rely on a lower ambient temperature in order to dissipate heat
away from sensitive electronics.
Arrival Frequency The arrival frequency refers to the set output frequency of the inverter for the
constant speed setting. The arrival frequency feature turns on an output when
the inverter reaches the set constant speed. The inverter has various arrival
frequencies and pulsed or latched logic options.
Auto-tuning The ability of a controller to execute a procedure that interacts with a load to
determine the proper coefficients to use in the control algorithm. Auto-tuning
is a common feature of process controllers with PID loops. Omron inverters
feature auto tuning to determine motor parameters for optimal commutation.
Auto-tuning is available as a special command from a digital operator panel.
See also Digital Operator Panel.
Base Frequency The power input frequency for which an AC induction motor is designed to
operate. Most motors will specify a 50 to 60 Hz value. The OmronOmron
inverters have a programmable base frequency, so you must ensure that
parameter matches the attached motor. The term base frequency helps differ-
entiate it from the carrier frequency. See also Carrier Frequency and Fre-
quency Setting.
Braking Resistor An energy-absorbing resistor that dissipates energy from a decelerating load.
Load inertia causes the motor to act as a generator during deceleration. For
the X200 inverter models, the braking unit and braking resistor are optional
(external) components. See also Four-quadrant Operation and Dynamic Brak-
ing.
Break-away Torque The torque a motor must produce to overcome the static friction of a load, in
order to start the load moving.
Carrier Frequency The frequency of the constant, periodic, switching waveform that the inverter
modulates to generate the AC output to the motor. See also PWM.
CE A regulatory agency for governing the performance of electronic products in
Europe. Drive installations designed to have CE approval must have particular
filter(s) installed in the application.
Choke An inductor that is tuned to react at radio frequencies is called a "choke,"
since it attenuates (chokes) frequencies above a particular threshold. Tuning
is often accomplished by using a movable magnetic core. In variable-fre-
quency drive systems, a choke positioned around high-current wiring can help
attenuate harmful harmonics and protect equipment. See also Harmonics.
DC Braking The inverter DC braking feature stops the AC commutation to the motor, and
sends a DC current through the motor windings in order to stop the motor.
Also called "DC injection braking," it has little effect at high speed, and is used
as the motor is nearing a stop.
Deadband In a control system, the range of input change for which there is no percepti-
ble change in the output. In PID loops, the error term may have a dead band
associated with it. Deadband may or may not be desirable; it depends on the
needs of the application.
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