Rockwell Automation AADvance Controller Demo Unit User Manual
Page 94
Demo Unit User Manual (AADvance Controller)
5-28
Document: 553850 Issue 1.2: March 2011
Overcurrent Protection for Digital Outputs
The AADvance controller has three mechanisms to protect its digital output channels:
Inrush current protection
Short circuit protection for energized channels
Short circuit protection for de-energized channels
The controller tolerates inrush currents so that its digital outputs can energize
capacitive loads without causing the controller to report a short circuit. The
illustration shows the characteristics of the maximum load currents that the controller
will tolerate when a digital output is commanded on. If the load current enters the
region above the curve on the graph, the controller applies its inrush current
protection.
After allowing for inrush, the controller engages its short circuit protection for an
energized channel when the loop current reaches 2A.
Short circuit detection on an energized channel is immediate and the channel is de-
energized. The controller reports the condition until the short circuit is cleared.
When the short circuit is removed, the channel will re-energize. The short circuit
report is then cleared by pressing the fault reset button on the 9110 processor
module or by setting the commanded state is set to FALSE.
The controller checks de-energized digital output channels for potential short circuits.
Periodically, the controller partially turns on each de-energized output in turn and
measures the loop current. If the loop current shows a loop resistance of less than
approximately 10Ω, the controller reports a short circuit.