Allen-Bradley PowerFlex User Manual

2-5
Step 3 Peak Braking Power
P
b
= Peak braking power (watts)
1.0 HP = 746 watts
J
T
= Total inertia reflected to the motor shaft (kg-m
2
)
ω
b
= Rated angular rotational speed
ω
o
= Angular rotational speed,
less than rated speed down to zero
N
b
= Rated motor speed (RPM)
t
3
– t
2
= Deceleration time from ω
b
to ω
o
(seconds)
Calculate Peak Braking Power:
Record Peak Braking Power:
Compare the peak braking power to that of the rated motor power. If the
peak braking power is greater that 1.5 times that of the motor, then the
deceleration time (t
3
– t
2
) needs to be increased so that the drive does not
go into current limit.
P
b
=
P
b
J
T
ω
b
ω
b
ω
o
–()[]
t
3
t
2
–()
----------------------------------------=
Rad
s
---------
2πN
b
60
------------=
Rad
s
---------
P
b
ooooooooo[]ooooooooo[]ooooooooo ooooooooo–()××
ooooooooo ooooooooo–()
-----------------------------------------------------------------------------------------------------------------------------------------------=

Allen-Bradley PowerFlex Specifications

General

Brand	Allen-Bradley
Model	PowerFlex
Category	DC Drives
Language	English