Mitsubishi Electric D75D4, User Manual

Page: 846 / 896

Appendix - 130
MELSEC-Q
APPENDICES
DYNAMIC BRAKE
When protection circuits operate due to power
failures, emergency stops (EMG signal) etc.,
this function is used to short-circuit between
servomotor terminals via a resistor, thermally
consume the rotation energy, and cause a
sudden stop without allowing coasting of the
motor.
Braking power is generated by
electromagnetic brakes only when running
motors with which a large brake torque can be
obtained. Because electromagnetic brakes
have no holding power, they are used in
combination with mechanical brakes to prevent
dropping of the vertical axis.
ELECTROMAGNETIC BRAKE
This function is supplied on motors with
electromagnetic brakes. Electromagnetic
brakes are used to prevent slipping during
power failures and faults when driving a
vertical axis, or as a protective function when
the machine is stopped.
These brakes are activated when not excited.
ELECTRONIC GEAR
This function electrically increases/decreases
the command pulses from the pulse command
module by 1/50 to 50-fold. Thus, the
positioning speed and movement amount can
be controlled by the electronic gear ratio
magnification.
EMERGENCY STOP
Emergency stops cannot be carried out by the
QD75, so a method of shutting OFF the servo
side power supply from outside the
programmable controller, etc., must be
considered.
ENCODER
This device turns the input data into a binary
code of 1 (ON) and 0 (OFF). A type of pulse
generator.
A
B
Z
Ball bearing
For the main
signal For the zero
point signal
Input axis
Code disk
Photoreceptor
(phototransistor)
Index
scale
Light source
(light-emitting diode)
Rotary encoder
a
a
b
z
b
Light source
(LED)
Collimator lens
Main scale
Photoreceptor
(photodiode)
Reference
zero point Index
scale
Linear encoder
ERROR CORRECTION
If a dimension error occurs in the machine,
and that error is actually smaller or larger than
1m in spite of a 1m command being issued
from the QD75, that error amount will be
compensated. For example, when the error is
actually smaller than 1m, the remaining
distance to 1m is fed, and the correct 1m of
positioning is carried out.
ERROR RESET
This resets error of axis. Note that if the cause
of the error is not eliminated at that time, the
error will occur again.