Filter
Top Products
12 - 4
12. CHARACTERISTICS
12.3 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. 12.4 shows the pattern in which the servo motor comes to a stop when the
dynamic brake is operated. Use Equation 12.2 to calculate an approximate coasting distance to a stop.
The dynamic brake time constant
varies with the servo motor and machine operation speeds. (Refer to
Fig. 12.5)
V
0
Time constant
Emergency stop(EMG)
OFF
ON
Machine speed
t
e
Time
Fig. 12.4 Dynamic brake operation diagram
L
max
60
V
0
J
L
J
M
t
e
1
....................................................................................................................... (12.2)
L
max
: Maximum coasting distance .................................................................................................[mm][in]
Vo : Machine rapid feedrate ......................................................................................... [mm/min][in/min]
J
M
: Servo motor inertial moment................................................................................. [kg cm
2
][oz in
2
]
J
L
: Load inertia moment converted into equivalent value on servo motor shaft.....[kg cm
2
][oz in
2
]
: Brake time constant (Fig. 12.5) ...................................................................................................... [s]
t
e
: Delay time of control section (Fig. 12.4)......................................................................................... [s]
(There is internal relay delay time of about 30ms.)