2 dynamic brake characteristics, Characteristics – MITSUBISHI ELECTRIC J2-JRSERIES MR-J2-03A5 User Manual
Page 141
11 - 2
11. 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 which 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
τ
varies with the servo motor and machine operation speeds. (Refer to Fig.
11.3.)
V
0
Time constant
τ
Emergency stop (EMG)
OFF
ON
Machine speed
t
e
Time
Fig. 11.2 Dynamic Brake Operation Diagram
Lmax =
60
Vo
x
+
+
M
L
J
J
1
te
(11.1)
L max : Maximum coasting distance
[mm][in]
Vo
: Machine rapid feedrate
[mm/min][in/min]
J
M
: Servo motor inertial moment
[kg x cm
2
][oz x in
2
]
J
L
: Load inertia moment converted into equivalent value on servo motor shaft
[kg x cm
2
][oz x in
2
]
τ
: Brake time constant (Fig. 11.3)
[s]
t
e
: Delay time of control section (Fig. 11.2)
[s]
(There is internal relay delay time of about 30ms.)
0
0.0005
0.001
0.0015
0.002
0.0025
0
100
400
700
1000 1300 1600
HC-AQ0135
HC-AQ0335
1900 2200 2500 2800 3000
HC-AQ0235
Ti
m
e
c
o
n
s
tant
τ
[s
]
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 higher than this value, the built-in dynamic brake may burn. If there is a possibility that the
load inertia moment may exceed the value, contact Mitsubishi.
Servo Amplifier
Load Inertia Moment Ratio [times]
MR-J2-03A5
100