A–5

SJ200 Inverter

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.

Jump Frequency

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.

Line Reactor

A three-phase inductor generally installed in the AC input circuit of

 

an inverter to minimize harmonics and to limit short-circuit current.

Momentum

The physical property of a body in motion that causes it to remain

 

in motion. In the case of motors, the rotor and attached load are

 

rotating and possesses angular momentum.

Multi-speed Operation

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.

Motor Load

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.

NEC

The National Electric Code is a regulatory document that governs

 

electrical power and device wiring and installation in the United

 

States.

NEMA

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.

Open-collector Outputs 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 connection (not connected internally). Thus, the output sinks external load current to ground.

Power Factor

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).

A Appendix