Nrtl Listing; Nfpa 79 - Siemens SINUMERIK 840D sl Function Manual

Regulations and Standards
1.3 Machine safety in the US
1.3.2

NRTL Listing

All electrical equipment and devices that are used in the US to protect workers
must be certified for the particular application by a "Nationally Recognized Testing
Laboratory" (NRTL) certified by OSHA. These "Nationally Recognized Testing Lab-
oratories" are authorized to certify equipment and material in the form of listing,
labeling or similar. Domestic Standards such as the NFPA 79 and also international
Standards such as e.g. EN 61508 for E/E/PES systems form the basis for testing.
1.3.3

NFPA 79

NFPA 79 (Electrical Standard for Industrial Machinery) applies to electrical equip-
ment on industrial machines with rated voltages of less than 600 V. (A group of
machines that operate together in a coordinated fashion is also considered to be
one machine.)
For programmable electronics and communication buses, NFPA 79 states as basic
requirement, that these must be listed if they are to be used to implement and exe-
cute safety–related functions. If this requirement is fulfilled, then electronic controls
and communication buses can also be used for Emergency Stop functions, Stop
Categories 0 and 1 (refer to NFPA 79 9.2.5.4.1.4). Just the same as EN 60204–1,
in the meantime, for Emergency Stop functions, NFPA 79 no longer specifies that
the electrical energy has to be disconnected using electro–mechanical elements.
The core requirements placed on programmable electronics and communication
buses include:
System requirements (refer to NFPA 79 9.4.3)
S Control systems that include software–based controllers, must,
(1) If an individual fault occurs,
– bring the system into a safe state to shut it down
– prevent restarting until the fault has been removed
– prevent unexpected starting
(2) Provide protection comparable to hard–wired controls
(3) Be implemented corresponding to a recognized Standard that defines the
requirements for such systems.
S EN 61508, EN 62061, ISO 13849–1/–2, EN 61800–5–2 are mentioned in a note
that they are suitable Standards.
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SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) – 05.2008 Edition
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05.08