Chapter 5 Operating Instructions
TR4
72 © SICK AG • Industrial Safety Systems • Germany • All rights reserved 8014467/YTD7/2016-03-30
Subject to change without notice
Electrical installation
en
5.2 Fault tolerance
• If the device does not appear to function after the application of the
supply voltage (e.g. Status/Diag LED does not flash), the safety
switch must be replaced.
• The supply voltage is reverse-polarity protected. The contacts
In A/In B and Out A/Out B are short-circuit protected.
• A cross-circuit between Out A and Out B is detected by the safety
switch. A cross-circuit in the cable can be prevented by laying the
cable with protection.
• A short-circuit on Out A or Out B to 24 V DC is detected. It is impera-
tive a simultaneous short-circuit on Out A and Out B to 24 V DC is
excluded by laying the cable with protection.
Cables must be laid with protection!
To prevent the accumulation of errors within the risk time, for applica-
tions as per SIL3 (IEC 61 508) and category 4 (EN ISO 13 849) it is
imperative to lay the cables with protection.
WARNING