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

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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. NRTLs are authorized to certify equipment
and material by means of listing, labeling, or similar. Domestic standards such as
the NFPA 79 and also international standards such as e.g. the series of IEC 61508
standards 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 ex-
ecute safety--related functions. If this requirement is fulfilled, then electronic con-
trols 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 like IEC 60204--1,
NFPA 79 no longer specifies that the electrical energy must be disconnected by
electromechanical means for Emergency Stop functions.
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.
Underwriter Laboratories (UL) has defined a special Category for "Program-
mable Safety Controllers" for implementing this requirement (code NRGF). This
category covers control devices that contain software and are designed for use
in safety--related functions.
A precise description of the category and a list of devices that fulfill this require-
ment can be found on the Internet at the following address:
http://www.ul.com
mation --> search for category "NRGF"
TUV Rheinland of North America, Inc. is also an NRTL for these applications.
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SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) - - 10.2015 Edition
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Regulations and standards
1.3 Machine safety in the USA
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