IEC 62061:2021/AMD1:2024

Amendment 1 - Safety of machinery - Functional safety of safety-related control systems

Amendement 1 - Sécurité des machines - Sécurité fonctionnelle des systèmes de commande relatifs à la sécurité

General Information

• Status: Published
• Publication Date: 27-Mar-2024
• ICS: 13.110 - Safety of machinery
• ICS: 25.040.99 - Other industrial automation systems
• ICS: 29.020 - Electrical engineering in general
• Technical Committee: TC 44 - Safety of machinery - Electrotechnical aspects
• Drafting Committee: MT 62061 - TC 44/MT 62061
• Current Stage: PPUB - Publication issued
• Start Date: 28-Mar-2024
• Completion Date: 12-Apr-2024

Relations

• Amends: IEC 62061:2021 - Safety of machinery - Functional safety of safety-related control systems
• Effective Date: 05-Sep-2023

Overview

IEC 62061:2021/AMD1:2024 is the latest amendment to the international standard focusing on the functional safety of safety-related control systems in machinery. Published by the International Electrotechnical Commission (IEC), this document enhances the foundational IEC 62061:2021 standard, ensuring up-to-date requirements and guidance for machinery safety. It addresses the design, integration, and validation of control systems that prevent hazards and minimize risks associated with machinery operations.

This amendment reflects critical updates impacting terminology, design processes, system requirements, security aspects, diagnostic methods, and software safety lifecycle modeling. It aligns the standard with the latest referenced standards such as IEC 61784-3:2021 and ISO/IEC 27001:2022, promoting modern requirements for cybersecurity and systematic fault control.

Key Topics

• Functional Safety Requirements
  Updated criteria for safety-related control systems emphasize preventing dangerous failures and managing both random hardware faults and systematic faults effectively.

• Design Process Enhancements
  Clarifications on the design lifecycle, including revised terminology and architectural constraints, improve the reliability of safety functions in machinery.

• Diagnostic Coverage and Fault Handling
  Improvements in formulas and diagnostics metrics such as Safe Failure Fraction (SFF) and Diagnostic Coverage (DC) provide better evaluation of system safety performance.

• Software Safety Lifecycle Model
  Amendments refine the V-model for software safety lifecycle at software safety integrity level (SIL) 2, supporting better software validation practices.

• Security Aspects for Control Systems
  Consideration for cybersecurity within safety-related control systems has been strengthened through updated references to security management standards.

• Updated References & Terminology
  Amendments include the replacement of IEC TR 63074 with IEC TS 63074, and update to ISO/IEC 27001:2022, ensuring harmonization with current industry standards.

Applications

The IEC 62061:2021/AMD1:2024 amendment applies broadly to the design and assessment of safety-related control systems in industrial machinery. It benefits the following sectors:

• Manufacturing Automation
  Enhances the safety of programmable electronic systems controlling mechanical equipment.

• Robotics
  Supports risk reduction in robot operation by defining safe control system architectures and fault diagnostics.

• Process Industry Machinery
  Improves functional safety frameworks for control systems managing complex processing equipment.

• Machine Builders and Integrators
  Guides the creation of compliant machine control systems to meet international safety requirements.

• Certification Bodies and Safety Assessors
  Facilitates evaluation and certification processes by providing updated safety parameters and testing criteria.

Related Standards

IEC 62061:2021/AMD1:2024 works in synergy with multiple standards, including:

• IEC 61508 – Functional safety of electrical/electronic/programmable electronic safety-related systems.
• IEC 61784-3:2021 – Industrial communication networks and functional safety communication profiles.
• IEC TS 63074:2023 – Guidance on functional safety of safety-related control systems.
• ISO/IEC 27001:2022 – Information security management systems fundamentals focusing on cybersecurity.
• IEC TS 63394:2023 – Guidelines on functional safety of safety-related control systems in machinery.

Practical Value

Implementing IEC 62061:2021/AMD1:2024 enables organizations to:

• Enhance machinery safety controls against failures and systematic faults.
• Ensure compliance with the latest international safety and security expectations.
• Improve risk assessment accuracy through refined diagnostic coverage calculations.
• Integrate cybersecurity measures within safety-related control architectures.
• Strengthen software safety lifecycle processes via updated verification and validation methods.

This amendment supports engineers, safety specialists, and compliance managers in mitigating risks and ensuring trustworthy safety-related systems aligned with global best practices in machinery safety and control system functional safety.

Keywords: IEC 62061 amendment 2024, functional safety machinery, safety-related control systems, machinery safety standards, IEC electrotechnical safety, safety diagnostics, control system cybersecurity, SIL machinery safety, IEC safety amendment, industrial machinery safety.

Standards Content (Sample)

IEC 62061 ®
Edition 2.0 2024-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
AMENDMENT 1
AMENDEMENT 1
Safety of machinery – Functional safety of safety-related control systems

Sécurité des machines – Sécurité fonctionnelle des systèmes de commande
relatifs à la sécurité
IEC 62061:2021-03/AMD1:2024-03(en-fr)

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IEC 62061 ®
Edition 2.0 2024-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
AMENDMENT 1
AMENDEMENT 1
Safety of machinery – Functional safety of safety-related control systems

Sécurité des machines – Sécurité fonctionnelle des systèmes de commande

relatifs à la sécurité
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 13.110, 25.040.99, 29.020 ISBN 978-2-8322-8509-1

– 2 – IEC 62061:2021/AMD1:2024
© IEC 2024
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SAFETY OF MACHINERY –
FUNCTIONAL SAFETY OF SAFETY-RELATED CONTROL SYSTEMS

AMENDMENT 1
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
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shall not be held responsible for identifying any or all such patent rights.
Amendment 1 to IEC 62061:2021 has been prepared by IEC technical committee 44: Safety of
machinery – Electrotechnical aspects.
The text of this Amendment is based on the following documents:
Draft Report on voting
44/1020/FDIS 44/1024/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Amendment is English.

© IEC 2024
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications/.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
____________
1 Scope
th rd
Replace, in the 6 paragraph, 3 dash, "IEC TR 63074" with "IEC TS 63074".

3.2.52
dangerous failure
Replace, in the source, "IEC 61508-4:2010, 3.6.4, modified – terminology adapted to machinery
and figure replaced by textual description and ISO 12100-1:2010, 3.34" with
"IEC 61508-4:2010, 3.6.7, modified – Terminology adapted to machinery".

4.2 Design process
Replace, in NOTE 1, "Annex H" with "Annex G".

6.5.2 Requirements for the control of systematic faults
Replace, in NOTE 2, "IEC 61784-3:2016" with "IEC 61784-3:2021".

6.8 Security aspects
Replace, in NOTE 2, "IEC TR 63074" with "IEC TS 63074".
Replace, in NOTE 2, "ISO/IEC 27001:2013" with "ISO/IEC 27001:2022".

– 4 – IEC 62061:2021/AMD1:2024
© IEC 2024
7.3.3.3 Fault exclusion
st
Replace, in the 1 NOTE, "NOTE" with "NOTE 1".
nd
Replace, in the 2 NOTE, "NOTE" with "NOTE 2".

7.3.4.2 Relationship of relevant parameters
th
Add, after the 11 paragraph (starting with "If the ratio of dangerous failure is estimated less
than 0,5"), the following new note and text:
B
NOTE 5 Similar to Formula (11), T is evaluated by .
T =
10 10
n
op
For further details, see IEC TS 63394:2023, Clause H.6.
Table 6 – Architectural constraints on a subsystem: maximum SIL that can be claimed
for an SCS using the subsystem
Replace, in NOTE 3, "7.4.3.2" with "7.5.3".
7.4.2 Estimation of safe failure fraction (SFF)
st
Replace, in the 1 paragraph, item b), "component failure data" with "failure rate data".
th
Replace, in the 4 paragraph, Formula (13) with the following new formula:
∑λλ+∑ ∑λ
S DD DD
SFF ≈
(13)
∑λλ+∑ ∑λ
SD D
th
Replace, in the 4 paragraph, "EXAMPLE 2" with "EXAMPLE 1".
th
Replace, in the 4 paragraph, the formula of the first EXAMPLE with the following:
λ DC λ
DD1 1 D1
SFF≈=  DC
λλ
D1 D1
th
Replace, in the 4 paragraph, "EXAMPLE 3" with "EXAMPLE 2".
th nd
Replace, in the 4 paragraph, the formula of 2 EXAMPLE with the following:
DC DC
+
λ ++ λ DC λ DC λ MTTF MTTF
DD1 DD2 1 D1 2 D2 D1 D2
SFF≈=
λλ + λ +λ
D1 D2 D1 D2
+
MTTF MTTF
D1 D2
=
=
=
© IEC 2024
7.4.3.3 Diagnostic coverage (DC)
st
Replace, in 1 paragraph, Formula (14) with the following:
∑λ
DD
DC=
(14)
∑λ
D
Figure 8 – Subsystem A logical representation
Replace, in the title, "Subsystem" with "Basic subsystem architecture".

Figure 9 – Subsystem B logical representation
Replace, in the title, "Subsystem" with "Basic subsystem architecture".

Figure 10 – Subsystem C logical representation
Replace, in the title, "Subsystem" with "Basic subsystem architecture".

Figure 11 – Subsystem D logical representation
Replace, in the title, "Subsystem" with "Basic subsystem architecture".

8.4.1.2 Software safety lifecycle model – SW level 2
Replace, in the last sentence of the 2nd paragraph, "9.5.3" with "9.5.4".

– 6 – IEC 62061:2021/AMD1:2024
© IEC 2024
Figure 14 – V-model of software safety lifecycle for SW level 2
Replace Figure 14 with the following new figure:

A.2.4.2 Frequency and duration of exposure
rd st
Delete, in the 3 paragraph, 1 sentence, the text "(referred to a period ≥ to one year)".

Table A.6 – Matrix assignment for determining the required SIL (or PL ) for a safety
r
function
Renumber the last "NOTE 3" as "NOTE 4".

B.4.2.4.2 Annex H approaches
nd
Replace, in the 2 dash, "T = 1/C = n /8 760 h" with
2 op
"T = 1 / C = 8 760 h / n ".
2 op
B.4.4.2.2 Annex H approaches
nd
Replace, in the 2 dash, "T = 1/C = n /8 760 h" with
2 op
"T = 1 / C = 8 760 h / n ".
2 op
B.4.5.1 Target
Replace "6.4.2" with "6.4.1".
© IEC 2024
B.4.5.3 Architectural constraints
st
Replace, in the 1 paragraph, "6.4.2" with "6.4.1".

Table C.1 – Standards references and MTTF or B values for components
D 10D
th rd
Add, in the 5 row ("Hydraulic components 250 000 > nop" and 3 column ("Other relevant
standards"), "ISO 4413".
st
Replace, in the 1 sentence of NOTE 3, "in the subsequent SCS" with "provided by another
subsystem of the SCS".
Table D.1 – Estimates for diagnostic coverage (DC)
th
Replace, in the 10 row and last column, "moving cart" with "moving part or final element".
th
Replace, in the 14 row and last column, "(placed in series or in parallel on the logic)" with
"(placed in series or on two separate inputs of the logic)".

E.1 General
Replace "two simple qualitative approaches" with "a simple qualitative approach".

E.2.2 Estimation of effect of CCF
st nd
Replace, in the 1 paragraph, 2 sentence, "safety-related parts of the control system" with
"SCS".
Table E.2 – Criteria for estimation of CCF
Replace, in the title, "Criteria for estimation of CCF" with "Estimation of CCF factor (β)".

H.1 Table allocation approach
nd th
Replace, in the 2 paragraph, 4 dash, "30 % of the PFH value" with "50 % of the PFH value".
nd
Replace, in the 2 sentence of NOTE 3, "common cause factor" with "common cause failure
factor".
– 8 – IEC 62061:2021/AMD1:2024
© IEC 2024
Figure H.1 – Subsystem A logical representation
Replace, in the title, "Subsystem" with "Basic subsystem architecture".

Figure H.2 – Subsystem B logical representation
Replace, in the title, "Subsystem" with "Basic subsystem architecture".

Figure H.3 – Subsystem C logical representation
Replace, in the title, "Subsystem" with "Basic subsystem architecture".

H.2.4.1 General
rd
Replace, in 3 paragraph, "7.4.3" with "7.4.3.2".

Figure H.4 – Correlation of subsystem C and the pertinent fault handling function
Replace Figure H.4 with the following new figure and title:

Figure H.4 – Correlation of basic subsystem architecture C
and the pertinent fault handling function

Figure H.5 – Subsystem C with external fault handling function
Replace, in the title, "Subsystem" w
...