Allen-Bradley 20A User Manual

Rockwell Automation Publication PFLEX-AT001L-EN-P - September 2017 23
Chapter 3
Evaluating the PowerFlex 7-Class Internal
Resistor
Evaluating the Capability of
the Internal Dynamic Brake
Resistor
To investigate the capabilities of the internal resistor package, the values of AL
(Average Percent Load) and
PL (Peak Percent Load) are plotted onto a graph of
the Dynamic Brake Resistor’s constant temperature power curve and connected
with a straight line. If any portion of this line lies to the right of the constant
temperature power curve, the resistor element temperature will exceed the
operating temperature limit.
1. Record the values calculated in
Chapter 2.
2A. Compare the calculated average power to the continuous rating of the
dynamic brake resistor in the frame drive you have selected.
See
Appendix A.
Record the resistor’s continuous rating.
IMPORTANT The drive will protect the resistor and shut down the Chopper transistor. The
drive will then likely trip on an over-voltage fault.
AL=
PL=
t
3
– t
2
=
P
ave
=
R
cont.
=

Allen-Bradley 20A Specifications

General

Brand	Allen-Bradley
Model	20A
Category	Controller
Language	English