5
4
SM Surge Rev 2
The surge protection devices covered by this manual are:
SD range
SD07, SD16, SD32, SD55
SD**R, SD**X, SD**R3,
SD**T3, SD**X3
SD32-L, SD32-BL, SDRTD
SD150X, SD275X
SLP range
SLP07D, SLP16D,
SLP32D
IOP range
IOP32, IOP32D, IOP
HC32
TP range
TP24/7, TP32, TP48**
System Configuration
The surge protection devices may be used as protective wiring components in functional safety applications but
the devices are not considered as ‘safety elements’ conforming to the requirements of IEC 61508. As stated
previously, the protection devices limit the energy seen by instrument systems as a consequence of external
electrical events such as induced surges, voltage transients, etc arising from lightning strikes or high voltage
switching for example. Users of these surge protection devices can utilize the failure rate information contained
in this manual in a probabilistic model of a Safety Instrumented Function (SIF) to determine suitability of the
safety instrumented system to achieve the required Safety Integrity Level (SIL).
The figure below shows an example system configuration and specifies detailed interfaces to the safety related
system components. It does not aim to show all details of the internal module structure, but is intended to
support understanding for the application.
The SD/SLP/IOP modules are designed to protect the input into the safety plc from damaging transients and
surge. The yellow (hatched) area shows the safety relevant system connection.
Consideration must be given to the use of dual channel devices when considering the integrity of the
installation. A failure in one channel of a two channel device will require replacement of the complete
module and the downtime of the two loops connected.
Otherwise, functionally the single channel and dual channel units are the same.
2.1.1
Input/Output Characteristics
The SD/SLP/IOP/TP surge protectors are passive devices and do not modify or alter the signal in normal
operation, but simply limit electrical energy.
2.1.2
Associated System Components
The surge protectors are wiring components in the signal path between safety-related sensors or other field
devices and safety-related instruments or control systems.
