Nfpa 79; Ansi B11 - Siemens SINAMICS S120 Function Manual

1.3.3

NFPA 79

NFPA 79 (Electrical Standard for Industrial Machinery) applies to the electrical equipment of
industrial machines with rated voltages of less than 600 V A group of machines that operate
with one another in a coordinated fashion is also considered to be a 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, electronic controls and communication buses
can also be used for emergency stop functions, 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/-2:2006, and IEC 61800-5-2 are specified as
Underwriter Laboratories (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.
1.3.4

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. Risk
analysis is an important requirement in accordance with NFPA79, ANSI/RIA 15.06, ANSI
B11.TR-3 and SEMI S10 (semiconductors). The documented findings of a risk analysis can
be used to select a suitable safety system based on the safety class of the application in
question.
Safety Integrated
Function Manual, (FHS), 11/2009, 6SL3097-4AR00-0BP0
– 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.
Standards and regulations
1.3 Machine safety in the USA
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