Hitachi L2002 Appendix A

A–2

Glossary

Appendix A

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 L2002 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.