Associated Equipment
890CS Common Bus Supply - Frames B & D; 890CD Common Bus Drive and 890SD Standalone Drive - Frames B, C & D
Page
6-11
8
9
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11
A
B
C
D
1
2
3
4
5
6
7
E
Calculation
Brake resistor assemblies must be rated to absorb both peak braking power during deceleration and the
average power over the complete cycle.
Peak braking power P
0 0055
n
n
t
W
1
2
2
2
b
=
×
−
.
(
)
(
)
pk
×
J
J
- total inertia (kgm
2
)
n
1
- initial speed (rpm)
Average braking power P
P
t
av
pk
c
=
x t
b
n
2
- final speed (rpm)
t
b
- braking time (s)
t
c
- cycle time (s)
Obtain information on the peak power rating and the average power rating of the resistors from the
resistor manufacturer. If this information is not available, a large safety margin must be incorporated to
ensure that the resistors are not overloaded.
By connecting these resistors in series and in parallel the braking capacity can be selected for the
application.
IMPORTANT
The minimum resistance of the combination and maximum dc link voltage must be as specified in
Appendix E: “Technical Specifications” - Internal Dynamic Brake Switch.
