Specifications

9.CHARACTERISTICS
9– 10
L max =
V
o
60
te + τ (1 +
J
L
J M
) •
.................................................... (9-3)
Lmax : Maximum coasting distance [mm][in]
Vo : Machine rapid feedrate [mm/min][in/min]
JM : Servo motor inertial moment [kg•cm
2
][oz•in
2
]
JL : Load inertia moment converted into equivalent value
on servo motor shaft [kg•cm
2
][oz•in
2
]
τ : Brake time constant (Fig. 9-6 to 9-12 • Table 9-3) [s]
te : Delay time of control section (Fig. 9-5) [s]
(There is internal relay delay time of about 30ms.)
9-4 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. 9-5 shows the pattern in which the servo motor comes to a
stop when the dynamic brake is operated. Use Equation 9-3 to calculate an approximate coasting
distance to a stop. The dynamic brake time constant τ varies with the servo motor and machine
operation speeds as indicated in Table 9-3 and as shown in Fig. 9-6 to Fig. 9-12.
Time constant τ [s]
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
0
50
500
0
1000
121
201
301
81
Speed
[r/min]
Emergency stop (EMG)
OFF
ON
Machine speed
V
0
t e
Time constant τ
Time
Time constant τ [s]
0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
0.016
0.018
0.02
0
500
1000
1500
2000
2500
3000
73
23
43
053
13
Speed
[r/min]
Fig. 9-4 Dynamic Brake Operation Diagram
Fig. 9-5 HC-MF Dynamic Brake
Time Constant
Fig. 9-6 HC-SF1000r/min Dynamic
Brake Time Constant