Instruction manual

1 1. CHARACTERISTICS
11.2 Dynamic Brake Characteristics
When an alarm, emergency stop or power failure occurs, the dynamic brake is operated to bring the servo
motor to a sudden stop. Fig. 11.2 shows the pattern in whch the servo motor comes to a stop when the
dynamic brake is operated. Use Equation 11.1 to calculate an approximate coasting distance to a stop. The
dynamic brake time constant T varies with the servo motor and machine operation speeds. (Refer to Fig.
11.3.)
Emergency stop (EMG)
OFF
T
Time constant T
Machine speed ~ Vo
--_ ! ----__------ .
b-4
Time
Fig. 11.2 Dynamic Brake Operation Diagram
hax- . ..............................................................
(11.1)
60
Lmax:Ma-umcoasting~stance .......................................................
Vo :Macherapidfeebate ...................................................
JM : Servo motor inertial moment ..............................................
[mml [in1
[mmlmin][dmin]
[kg * cm2][oz * in21
JL : Load inertia moment converted into equivalent value on servo motor shaft ..... [kg . cmz][oz . in21
T :Braketimeconstant(Fig.11,3) [SI
[SI
..........................................................
: Delay tirne of control section (Fig, 11.2) ...................................................
(There is internal relay delay time of about 30ms.)
0.0025
7.i I 0.002.
LC-AQO135
P
c
5 0.0015
’ HC-Am235
L
v)
t
E
’
8 0.001
i
i= 0.0005
.
0
HC-AW335
‘0 I00 400 700 1000 1300 1600 1900 2200 2500 2800 3000
Speed [r/min]
Fig. 11.3 Dynamic Brake Time Constant
Use the dynamic brake at the load inertia moment indicated in the following table. If the load inertia
moment is hgher than ths value, the bdt-in dynamic brake may burn. If there is a possibility that the
load inertia moment may exceed the value, contact Wtsubish.
Servo Amplifier Load Inertia Moment Ratio [times]
MR-J2-03A5
100
11 - 2