Hitachi SJ300-037HFE Manual De Usuario

Glossary

Appendix A

A transformer with 1:1 voltage ratio that provides electrical isolation 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.

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.

A jump frequency is a point on the inverter output frequency range that you want the inverter to 
skip around. This feature may be used to avoid a resonant frequency, and you can program up 
to three jump frequencies in the inverter.

A three-phase inductor generally installed in the AC input circuit of an inverter to minimize 
harmonics and to limit short-circuit current.

The physical property of a body in motion that causes it to continue to remain in motion. In the 
case of motors, the rotor and attached load are rotating and possess angular momentum.

The ability of a motor drive to store preset discrete speed levels for the motor, and control 
motor speed according to the currently selected speed preset. The Hitachi inverters have 16 
preset speeds.

In motor terminology, motor load consists of the inertia of the physical mass that is moved by 
the motor and the related friction from guiding mechanisms. See also inertia.

The National Electric Code is a regulatory document that governs electrical power and device 
wiring and installation in the United States.

The National Electric Manufacturer’s Association. NEMA Codes are a published series of 
device ratings standards. Industry uses these to evaluate or compare the performance of devices 
made by various manufacturers to a known standard.

A common logic-type discrete output that uses an NPN transistor that acts as a switch to a 
power supply common, usually ground. The transistor’s collector is open for external connec-
tion (not connected internally). Thus, the output sinks external load current to ground.

When using the expansion card SJ-FB with encoder feedback, the orientation feature is avail-
able. Also called home search in motion terminology, you can specify a search direction and a 
stop position. Typically the orientation procedure is necessary after each inverter powerup.

A ratio that expresses a phase difference (timing offset) between current and voltage supplied 
by a power source to a load. A perfect power factor = 1.0 (no phase offset). Power factors less 
than one cause some energy loss in power transmission wiring (source to load). 

Proportional-Integral-Derivative – a mathematical model used for process control. A process 
controller maintains a process variable (PV) at a setpoint (SP) by using its PID algorithm to 
compensate for dynamic conditions and varies its output to drive the PV toward the desired 
value. See also error.

A physical property of a process that is of interest because it affects the quality of the primary 
task accomplished by the process. For an industrial oven, temperature is the process variable. 
See also PID Loop and error.

Pulse-width modulation: A type of AC adjustable frequency drive that accomplishes frequency 
and voltage control at the output section (inverter) of the drive. The drive output voltage 
waveform is at a constant amplitude, and by “chopping” the waveform (pulse-width-modulat-
ing), the average voltage is controlled. The chopping frequency is sometimes called the carrier 
frequency.