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Glossary
Appendix A
A–2
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. Hitachi inverters feature auto tuning to determine
motor parameters for optimal commutation. Auto-tuning is avail-
able 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 Hitachi inverters have a programmable base frequency, so you
must ensure that parameter matches the attached motor. The term
base frequency helps differentiate it from the carrier frequency. See
also Carrier Frequency and Frequency Setting.
Braking Resistor An energy-absorbing resistor that dissipates energy from a deceler-
ating load. Load inertia causes the motor to act as a generator
during deceleration. For the L200 inverter models, the braking unit
and braking resistor are optional (external) components. See also
Four-quadrant Operation and Dynamic Braking.
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-frequency drive systems, a choke
positioned around high-current wiring can help attenuate harmful
harmonics and protect equipment. See also Harmonics.