A–4

Glossary

Appendix A

Frequency Setting

While frequency has a broad meaning in electronics, it typically

 

refers to motor speed for variable-frequency drives (inverters). This

 

is because the output frequency of the inverter is variable, and is

 

proportional to the attained motor speed. For example, a motor with

 

a base frequency of 60 Hz can be speed controlled with an inverter

 

output varying form 0 to 60 Hz. See also Base Frequency, Carrier

 

Frequency, and Slip.

Harmonics

A harmonic is a whole number multiple of a base of fundamental

 

frequency. The square waves used in inverters produce high-

 

frequency harmonics, even though the main goal is to produce

 

lower-frequency sine waves. These harmonics can be harmful to

 

electronics (including motor windings) and cause radiated energy

 

that interferes with nearby electronic devices. Chokes, line reactors,

 

and filters are sometimes used to suppress the transmission of

 

harmonics in an electrical system. See also Choke.

Horsepower

A unit of physical measure to quantify the amount of work done per

 

unit of time. You can directly convert between horsepower and

 

Watts as measurements of power.

IGBT

Insulated Gate Bipolar Transistor (IGBT) – A semiconductor

 

transistor capable of conducting very large currents when in satura-

 

tion and capable of withstanding very high voltages when it is OFF.

 

This high-power bipolar transistor is the type used in Hitachi invert-

 

ers.

Inertia

The natural resistance a stationary object to being moved by an

 

external force. See also Momentum.

Intelligent Terminal

A configurable input or output logic function on the Hitachi invert-

 

ers. Each terminal may be assigned one of several functions.

Intelligent Sensorless Vector Control (iSLV)

Inverter

Intelligent Sensorless Vector Control (iSLV) is Hitachi’s newest variable speed control technology. The original sensorless vector control (SLV) did not require motor shaft position sensors (thus “sensorless)”, but still required setting several motor parameters (either manually or through an auto-tuning procedure). Now, iSLV uses proprietary Hitachi algorithms and high-speed processing to provide smooth control that adapts to motor characteristics in real time. Even the need to do auto-tuning procedures has been elimi- nated.

A device that electronically changes DC to AC current through an alternating process of switching the input to the output, inverted and non-inverted. A variable speed drive such as the Hitachi SJ200 is also called an inverter, since it contains three inverter circuits to generate 3-phase output to the motor.