Allen-Bradley 20G - Chapter 2; Determine Values of Equation Variables

14 Rockwell Automation Publication PFLEX-AT001L-EN-P - September 2017
Chapter 2 Determining Dynamic Brake Requirements
Determine Values of
Equation Variables
Step 1 – Total Inertia
J
T
= Total inertia reflected to the motor shaft
(kg•m
2
or WK
2
in lb•ft
2
)
J
m
= Motor inertia (kg•m
2
or WK
2
in lb•ft
2
)
GR = Gear ratio for any gear between motor and load (dimensionless)
If the gear ratio is 2:1 then
J
L
= Load inertia (kg•m
2
or WK
2
in lb•ft
2
)
1.0 lb•ft
2
= 0.04214011 kg•m
2
Calculate Total Inertia:
Record Total Inertia:
J
T
=
J
T
J
m
GR
2
J
L


+=
GR
Load Speed
Motor Speed
---------------------------- -=
GR
1
2
--
0.5==
J
T
oooooooooooooooooooo oooooooooo+=