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Glossary
Appendix A
Frequency Setting | While frequency has a broad meaning in electronics, it typically |
| refers to motor speed for |
| 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 |
| |
| 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 |
| 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. |
Inverter | A device that electronically changes DC to AC current through an |
| alternating process of switching the input to the output, inverted and |
| |
| also called an inverter, since it contains three inverter circuits to |
| generate |
Isolation Transformer | A transformer with 1:1 voltage ratio that provides electrical isola- |
| tion between its primary and secondary windings. These are |
| typically used on the power input side of the device to be protected. |
| An isolation transformer can protect equipment from a ground fault |
| or other malfunction of nearby equipment, as well as attenuate |
| harmful harmonics and transients on the input power. |
Jogging Operation | Usually done manually, a jog command from an operator’s panel |
| requests the motor/drive system to run indefinitely in a particular |
| direction, until the machine operator ends the jog operation. |