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15. USING A DIRECT DRIVE MOTOR
15 - 21
(b) Dynamic brake time constant
The following shows necessary dynamic brake time constant τ for equation 15.1.
Time constant [ms]
Speed [r/min]
0
0 100 200
5
15
20
25
30
300 400 500
006
004
10
002
0
0 100 200
70
300 400 500
012
006
018
10
20
30
40
50
60
Speed [r/min]
Time constant [ms]
TM-RFM_C20 TM-RFM_E20
0
0
10
30
40
50
60
20
100 200 300 400 500
Speed [r/min]
072
048
012
Time constant [ms]
0
0
60
50 100 150 200
70
80
50
40
30
20
10
Speed [r/min]
120
040
240
Time constant [ms]
TM-RFM_G20 TM-RFM_J10
(2) Permissible load to motor inertia ratio when the dynamic brake is used
Use the dynamic brake under the load to motor inertia ratio indicated in the following table. If the load
inertia moment is higher than this value, the dynamic brake may burn. If the load to motor inertia ratio
exceeds the indicated value, contact your local sales office.
The values of the permissible load to motor inertia ratio in the table are the values at the maximum
rotation speed of the direct drive motor.
The value in the parenthesis shows the value at the rated speed of the direct drive motor.
Direct drive motor
Permissible load to motor inertia ratio
[multiplier]
TM-RFM_C20
100 (300)
TM-RFM_E20
TM-RFM_G20 50 (300)
TM-RFM_J10 50 (200)