Table of Contents
Pulse Testing for Inputs
Pulse Testing Functions
Your DG safety relay uses pulse testing of inputs with voltage free contacts to
detect short circuit conditions. The test pulses are used to detect three short
circuit conditions:
• Between the input terminals and +24V
• Between the input terminals and 24V common
• Between the two input terminals.
Pulse testing for the inputs must be used with devices like E-stop push buttons,
tongue operated interlock switches, and limit switches that have voltage-free
contacts.
The pulse-testing cannot be turned on or off and cannot be changed.
Therefore, the purpose of this chapter is informational, but it can be used
during troubleshooting of a DG safety circuit.
Pulse tests for the inputs are generated on terminals S11 and S21 of the DG
safety relay.
Figure 39
shows the pulse testing that is associated with the DG safety relay.
The pulse widths are either 300 µs or 600 µs wide, and the pulses are repeated
every 15 ms.
Figure 39 - Pulse Test Sequence for DG Safety Relay
24V
S21
0V
0.3
24V
S11
0V
0
0.6
Rockwell Automation Publication 440R-UM015C-EN-P - April 2018
15.3
15 15.6
Time [ms]
7
Chapter
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