Siemens Simatic S7-1500R System Manual page 112

Reference potential of the controller
The reference potential of the S7-1500R/H redundant system is connected to the mounting
rail over a high-resistance RC combination in the R/H-CPU. This connection conducts high-
frequency interference currents and prevents electrostatic charges. Despite the grounded
mounting rail, the reference potential of the S7-1500R/H redundant system has to be
considered as ungrounded due to the high-resistance connection.
If you want to configure the S7-1500R/H redundant system with a grounded reference
potential, establish an electrical connection between the M connection of the CPU and the
protective conductor.
You can find a simplified representation of the potentials in the section Electrical
configuration (Page 113).
Short-circuit and overload protection
Various measures as protection against short-circuits and overloads are required for setting
up a full installation. The nature of the components and the degree to which the required
measures are binding depends on the IEC (DIN VDE) regulation applicable to your plant
configuration. The table refers to the following figure and compares the IEC (DIN VDE)
regulations.
Table 5- 1 Components and required measures
Shut-off device for control system, sen-
sors, and actuators
Short-circuit and overload protection:
In groups for sensors and actuators
Load power supply for AC load circuits
with more than five items of electromag-
netic equipment
S7-1500R/H redundant system
System Manual, 10/2018, A5E41814787-AA
Reference to follow-
ing figure
①
Main switch
②
Single-pole protection of
circuits
③
④
Galvanic isolation by
transformer recommended
5.2 Operation on grounded infeed
IEC 60364
(DIN VDE 0100)
Disconnector
•
•
Galvanic isolation by
transformer recommended
Wiring
IEC 60204
(DIN VDE 0113)
With grounded sec-
ondary circuit: Single-
pole protection
Otherwise: All-pole
protection
111