Dynamic Brake Characteristics - Mitsubishi Electric MELSERVO MR-J2S- A Instruction Manual

12. CHARACTERISTICS

12.3 Dynamic brake characteristics

Fig. 12.6 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. 12.7. Please contact
us for the servo motor not indicated.)
Emergency stop(EMG)
J
V
0
L t
1
e
max
60
J
L : Maximum coasting distance .................................................................................................[mm][in]
max
Vo : Machine rapid feedrate ......................................................................................... [mm/min][in/min]
J : Servo motor inertial moment................................................................................. [kg cm
M
J : Load inertia moment converted into equivalent value on servo motor shaft..... [kg cm
L
: Brake time constant ........................................................................................................................ [s]
t : Delay time of control section........................................................................................................... [s]
e
For 7kW or less servo, there is internal relay delay time of about 30ms. For 11kW to 22kW
servo, there is delay time of about 100ms caused by a delay of the external relay and a delay of
the magnetic contactor built in the external dynamic brake.
16
14
12
10
8 053
6
4
2
0
0 500 1000 1500 2000 2500 3000
a. HC-KFS series
ON
OFF
V
Machine speed
Fig. 12.6 Dynamic brake operation diagram
L
....................................................................................................................... (12.2)
M
23
73
43
13
Speed[r/min]
Fig. 12.7 Dynamic brake time constant 1
0
t
e
0.02
0.018
0.016
0.014
0.012
0.01
0.008
0.006
0.004
0.002
0
12 - 5
Time constant
Time
23
0 500 1000 1500 2000 2500 3000
Speed [r/min]
b. HC-MFS series
][oz in ]
2 2
][oz in ]
2 2
73
053
43
13