79 9.2.5.4.1.4). Just the same as 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 in
accordance with NFPA 79 9.4.3:
1. Control systems that contain software-based controllers must:
– In the event of a single fault
(a) Initiate that the system switches 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.
2. IEC 61508, IEC 62061, ISO 13849-1, ISO 13849‑2 and IEC 61800-5-2 are specified as
suitable standards in a note.
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:
NRGF (
) → Online Certifications Directory → UL Category code/Guide
information → search for category "NRGF"
TUV Rheinland of North America, Inc. is also an NRTL for these applications.
A.4.3.4
ANSI B11
ANSI B11 standards are joint standards developed by associations such as the Association
for Manufacturing Technology (AMT) and the Robotic Industries Association (RIA).
The hazards of a machine are evaluated by means of a risk analysis/assessment. The risk
analysis is an important requirement in accordance with NFPA 79, ANSI/RIA 15.06, ANSI
B11.TR-3 and SEMI S10 (semiconductors). The documented results of a risk analysis can be
used to select a suitable safety system based on the safety class of the application in question.
A.4.4
Machine safety in Japan
The situation in Japan is different from that in Europe and the US. Legislation such as that
prescribed in Europe does not exist. Similarly, product liability does not play such an important
role as it does in the US.
Appendix
A.4 Standards and specifications
Safety Integrated - SINAMICS G110M, G120, G120C, G120D and SIMATIC ET 200pro FC-2
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