Hitachi L200 Manual Do Utilizador

L200 Inverter

Appendix A

The inverter DC braking feature stops the AC commutation to the 
motor, and sends a DC current through the motor windings in order 
to stop the motor. Also called “DC injection braking,” it has little 
effect at high speed, and is used as the motor is nearing a stop.

In a control system, the range of input change for which there is no 
perceptible change in the output. In PID loops, the error term may 
have a dead band associated with it. Deadband may or may not be 
desirable; it depends on the needs of the application.

For Hitachi inverters, “digital operator panel” (DOP) refers first to 
the operator keypad on the front panel of the inverter. It also 
includes hand-held remote keypads, which connect to the inverter 
via a cable. Finally, the DOP Professional is a PC-based software 
simulation of the keypad devices.

A semiconductor device that has a voltage-current characteristic 
that allows current to flow only in one direction, with negligible 
leakage current in the reverse direction. See also Rectifier.

1. The percent of time a square wave of fixed frequency is ON 
(high) versus OFF (low). 2. The ratio of operating time of a device 
such as a motor to its resting time. This parameter usually is speci-
fied in association with the allowable thermal rise for the device.

For the L200 inverter models, the braking unit and braking resistor 
are optional (external) components. The dynamic braking feature 
shunts the motor-generated EMF energy into a special braking 
resistor. The added dissipation (braking torque) is effective at 
higher speeds, having a reduced effect as the motor nears a stop.

In process control, the error is the difference between the desired 
value or setpoint (SP) and the actual value of a the process variable 
(PV). See also Process Variable and PID Loop.

Electromagnetic Interference - In motor/drive systems, the switch-
ing of high currents and voltages creates the possibility of generat-
ing radiated electrical noise that may interfere with the operation of 
nearby sensitive electrical instruments or devices. Certain aspects of 
an installation, such as long motor lead wire lengths, tend to 
increase the chance of EMI. Hitachi provides accessory filter 
components you can install to decrease the level of EMI.

Referring to a graph of torque versus direction, a four-quadrant 
drive can turn the motor either forward or reverse, as well as decel-
erate in either direction (see also reverse torque). A load that has a 
relatively high inertia and must move in both directions and change 
directions rapidly requires four-quadrant capability from its drive.