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Glossary
A
mbient
T
emperature
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.
A
rrival 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.
A
uto-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 available
as a special command from a digital operator panel. See also
Digital
Operator Panel
.
B
ase 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
.
B
raking 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 L200 inverter models, the braking unit
and braking resistor are optional (external) components. See also
Four-quadrant Operation
and
Dynamic Braking.
B
reak-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
.
A2
Appendix A
A 2
Appendix A