User Manual

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
= LBFT
Step 2 -- Determine the Total Inertia
wk
2
t = + [ × ( )
2
]
wk
2
t = wk
2
M
+ [wk
2
L
× (GR)
2
]
wk
2
M
= The motor inertia
wk
2
L
= The load inertia
GR = The total reduction ratio Output RPM
Input RPM
wk
2
t = LBFT
2
Step 3 -- Determine the Required Braking Torque
TQ
B
= [ ] × [ - ]
308 × [ ]
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
= LBFT
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.