Rockwell Automation 1333 Drive, 3/4-5HP, 230-575V Series D - Manual (Page 131)

Application Data
Appendix D
D-4
Step 1 -- Determine the Rated Motor Torque
TQ
M
= 5250 ×
TQ
M
= 5250 × HP
N
HP = The nameplate horsepower of the motor
N = The nameplate base speed of the motor
TQ
M
= LBĆFT
Step 2 -- Determine the Total Inertia
wk 2 t = + [ × ( ) 2 ]
wk 2 t = wk 2M + [wk 2L
× (GR) 2 ]
wk 2M = The motor inertia
wk 2L = The load inertia
GR = The total reduction ratio Output RPM
Input RPM
wk 2 t = LBĆFT 2
Step 3 -- Determine the Required Braking Torque
TQ
B
= [ ] Ч [ - ]
308 Ч [ ]
TQ
B
= wk 2 t × [N
2
- N
1
]
308 × t
2
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
= LBĆFT
Step 4 -- Determine the Required Percent of Braking Torque
TQ
%
= [ ] × 100
[ ]
TQ
%
= TQ
B
× 100
TQ
M
TQ
B
= The required braking torque
TQ
M
= The rated motor torque
TQ
%
= %
If
TQ
% is less than 20%, heavy duty 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 heavy duty braking kit is required. Continue to
Step 5.