Hitachi L100 Manuel D’Utilisation

Page de 192
L100 Inverter
Appendix A
A–5
Jump Frequency
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). 
PID Loop
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.
Process Variable
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.