Connection
5.2 Operation of the CM on grounded/ungrounded power supply
SIMATIC RF185C, RF186C, RF188C, RF186CI, RF188CI
32 Operating Instructions, 04/2020, C79000-G8976-C512-03
Components and protective measures
Various components and protective measures are prescribed for plant installations. The
types of components and the degree to which the protective measures are mandatory
depend on the IEC regulation that applies to your plant setup.
The following table shows the components of the electrical design with reference to the
previous figure and compares the IEC regulations.
Table 5- 1 Components of the electrical design
①
Disconnecting device for
controller, sensors, and
Main switch Disconnector
Short-circuit and overload
protection
Single-pole protection of
circuits.
Protect all power supply
lines with a 24 V DC / 16 A
Single-pole protection must
be used for a grounded
secondary circuit.
③
Circuit breaker Protection of cables and
lines against overcurrent
--
Insulation monitoring
Isolation monitoring must be provided in the following cases:
● Design of the communication module with an ungrounded reference potential
● If hazardous plant states can be expected as a result of faults.
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