Nfpa 79 - Siemens SINAMICS G120 Function Manual

Appendix
A.1 Standards and specifications
A.1.3.3

NFPA 79

Standard NFPA 79 (Electrical Standard for Industrial Machinery) applies to electrical
equipment 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 a basic
requirement that these must be listed if they are to be used to implement and execute 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). Like EN 60204-1, NFPA 79 no longer specifies that the electrical
energy must be disconnected by electromechanical means for emergency stop functions.
The core requirements regarding programmable electronics and communication buses are:
system requirements (see NFPA 79 9.4.3)
1. Control systems that contain software-based controllers must:
2. IEC 61508, IEC 62061, ISO 13849-1, ISO 13849-2 and IEC 61800-5-2 are specified as
Underwriter Laboratories Inc. (UL) has defined a special category for "Programmable 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 requirement can be
found on the Internet at the following address:
http://www.ul.com → certifications directory → UL Category code/ Guide information → search
for category "NRGF"
TUV Rheinland of North America, Inc. is also an NRTL for these applications.
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– In the event of a single fault
(a) cause the system to switch to a safe shutdown mode
(b) prevent the system from restarting until the fault has been rectified
(c) prevent an unexpected restart
– Offer the same level of protection as hard-wired controllers
– Be implemented in accordance with a recognized standard that defines the
requirements for such systems.
suitable standards in a note.
Safety Integrated Function Manual, SINAMICS G120 and G120C
Function Manual, 01/2011, FW 4.4, A5E03052391B AB