Rockwell Automation 1791DS-IBxxxx Guard I/O DeviceNet Safety Modules - Manual (Page 16)

16 Rockwell Automation Publication 1791DS-UM001J-EN-P - May 2013
Chapter 1 About the Modules
For 1791DS-IB4XOW4 modules, follow these instructions on isolating
transformer use. Refer to the isolating transformer figure.
• Use an isolating transformer to isolate between over-voltage category III
and II, such as TR1, to conform to IEC 60742.
• Be sure the insulation between first input and secondary output satisfies at
least basic insulation of over-voltage category III.
• Be sure one side of a secondary output of the isolating transformer is
grounded to prevent electric shock to personnel due to a short to ground
or short to the frame of the isolating transformer.
• Insert fuses, in case of a short to the frame, to protect the isolating
transformer and prevent electric shock to personnel, per transformer
specifications, at points such as F1, F2, and F3.
Figure 1 - Use of Isolating Transformer
1791DS-IB4XOW4 Module
L1 L2 L3
400V AC/ 230V AC
III Over-voltage Category II
F1…F8 - Fuses
MA, MB - Electromagnetic Switches
TR1 - Insulated Transformer
44151
F6 F7
F8 F2
F1
TR1
F3
F4 F5
MA MB
MA
MB
Load