J
oggingOperation 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.
J
umpFrequency 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.
L
ineReactor A three-phase inductor generally installed in the AC input circuit of
an inverter to minimize harmonics and to limit short-circuit current.
M
omentum 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.
M
ulti-speed
O
peration
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.
M
otorLoad 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
.
N
EC The National Electric Code is a regulatory document that governs
electrical power and device wiring and installation in the United
States.
EMA 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.
O
pen-collector
O
utputs
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.
P
owerFactor 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).
P
IDLoop 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 vary its output to drive the PV toward the
desired value. For variable-frequency drives, the process variable is
the motor speed. See also
Error
.

A5

Appendix A
A 5
Appendix A