Hitachi SJ300-037HFE 사용자 설명서

Glossary

Appendix A

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.

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.

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.

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.

An energy-absorbing resistor that dissipates energy from a decelerating load. Load inertia 
causes the motor to act as a generator during deceleration. See also four-quadrant operation 
and dynamic braking.

The torque a motor must produce to overcome the static friction of a load in order to start the 
load moving.

The frequency of the constant, periodic, switching waveform that the inverter modulates to 
generate the AC output to the motor. See also PWM.

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 applica-
tion.

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 harmon-
ics.

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.

The portion of the variable frequency drive between the input rectifiers and the output stages. It 
delivers smoothed DC power to the control and output stages of the drive.

In a control system, the range of input change for which there is no perceptible change in the 
output. In PID loops, the error term may have a deadband associated with it. Deadband may or 
may not be desirable; it depends on the needs of the application.

For Hitachi inverters, “digital operator panel” (DOP) refers first to the operator keypad on the 
front panel of the inverter. It also includes hand-held remote keypads, which connect to the 
inverter via a cable. Finally, the DOP Professional is a PC-based software simulation of the 
keypad devices.