SMC Networks LECSB2-T Series User Manual

15. SERVO MOTOR
15 - 2
15. SERVO MOTOR
15.1 Servo motor with a lock
15.1.1 Features
CAUTION
The lock is provided to prevent a drop at a power failure or servo alarm
occurrence during vertical drive or to hold a shaft at a stop. Do not use it for
normal braking (including braking at servo-lock).
The lock has a time lag. Use the lock so that servo motor control starts after the
lock has completely opened. Be sure to check the time lag of the locking with a
real machine.
Configure a lock circuit so that it is activated also by an external EMG stop switch.
While the lock is opened, the motor may be raised to high temperature regardless
of driving.
The life will be shorten under sudden acceleration/deceleration conditions.
The servo motor with a lock can be used to prevent a drop in vertical lift applications or to ensure double
safety at an emergency stop, for example. When operating the servo motor, supply power to the lock to
release the lock. Switching power off enables the lock.
(1) Lock power supply
Prepare the following power supply for use with the lock only. The lock terminals (B1 and B2) have no
polarity.
Electromagnetic brake
Switch
VAR
B1
U
B
24 V DC
power supply for
electromagnetic brake
B2
Electromagnetic brake
Switch
VAR
B1
U
B
24 V DC
power supply for
electromagnetic brake
B2
or
The surge absorber (VAR) must be installed between B1 and B2. When you use a diode for a surge
absorber, the locking time will be longer.
(2) Sound generation
Though the brake lining may rattle during operation, it poses no functional problem.
If braking sounds, it may be improved by setting the machine resonance suppression filter in the
driver parameters.
(3) Selection of surge absorbers for lock circuit
The following shows an example how to select a varistor with a surge absorber.
(a) Selection conditions
Item
Condition
24 V DC
Relay
Brake coil
U
Varistor
Lock specification
R [Ω]: Resistance
(Note)
L [H]: Inductance
(Note)
Vb [V]: Power supply voltage
Desired suppression
voltage
Vs [V] or less
Durable surge application
time
N times
Note. Refer to section 15.1.2.
lock
lock
lock
lock
lock coil

SMC Networks LECSB2-T Series Specifications

General

Brand	SMC Networks
Model	LECSB2-T Series
Category	DC Drives
Language	English