Rockwell Automation 1305 DYNAMIC BRAKES - Manual (Page 3)

1305 Dynamic Brake 3
1305-5.11 May, 1999
Step 1 — Determine the Rated Motor Torque How to Select a Brake
(continued)
where:
HP = The nameplate HP of the motor.
N = The nameplate base speed of the motor.
TQ
M
= LB-FT
TQ
M
= 5250
×
HP
——————
N
TQ
M
= 5250
×
——————
Step 2 — Determine the Total Inertia
where:
wk 2M = The motor inertia.
wk 2L = The load inertia.
GR = The total reduction ratio Output RPM
——————
Input RPM
wk 2 t = LB-FT 2
wk 2 t = wk 2M + [ wk 2L ×
( GR ) 2 ]
wk 2 t = + [
×
( ) 2 ]
Step 3 — Determine the Required Braking Torque
where:
wk 2
t
= The total inertia.
N
2
= The motor’s maximum speed.
N
1
= The motor’s minimum speed.
t
2
= The motor’s decel time.
TQ
B
= LB-FT
TQ
B
= wk 2 t
×
[ N
2
−
N
1
]
——————————
308
×
t
2
TQ
B
= [ ]
Ч
[
−
]
———————————
308
Ч
[ ]
Step 4 — Determine the Required Percent of Braking Torque
where:
TQ B = The required braking torque.
TQ M = The rated motor torque.
TQ% = %
TQ% = TQ B
×
100
——
TQ M
TQ% = [ ]
×
100
———
[ ]
If TQ% is less than 20%, dynamic braking is not required. The inherent
braking of the drive should be sufficient to handle the application
requirements.
If TQ% is 20% or more, a dynamic brake is required. Continue to Step 5 .