Hitachi WJ200-001L, Инструкция по эксплуатации, Страница: 330 / 680

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DC Braking 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.
Deadband 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.
Digital Operator
Panel 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.
Diode 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
.
Duty Cycle 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 specified in association
with the allowable thermal rise for the device.
Dynamic Braking For the X200
2
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.
EDM [
Functional Safety Related Term
] External Device Monitoring, the
output signal from inverter to external device in order to feed back
the status that the both safety path working properly. Safety
certificate is issued based on the condition that this EDM signal is
interfaced to certified external device to avoid restarting or to inform
in case of failure in safety path.
Error 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
.
EMI Electromagnetic Interference - In motor/drive systems, the switching
of high currents and voltages creates the possibility of generating
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.
Four-quadrant
operation Referring to a graph of torque versus direction, a four-quadrant drive
can turn the motor either forward or reverse, as well as decelerate in
either direction (see also
reverse torque
). A load that has a relatively