IEC 62061:2021

Overview

IEC 62061:2021 - "Safety of machinery - Functional safety of safety-related control systems" - is a machinery-sector standard that specifies requirements and recommendations for the design, integration and validation of safety-related control systems (SCS) used to carry out safety functions on machines (non-portable by hand), including coordinated groups of machines. It sits within the framework of IEC 61508 (all parts) and focuses on functional safety to reduce risks arising directly from machine hazards. This edition (2021, consolidated with 2024 amendment) updates structure, extends scope to non‑electrical technologies, and adds new guidance on software, architectures and validation.

Key topics and technical requirements

• Safety requirements specification (SRS) - definition of safety functions, demand mode estimation and safety integrity requirements.
• Design process and management - top‑down SCS design, subsystem decomposition, functional safety plan and configuration management (Clause 4).
• Safety integrity and reliability - determination of required safety integrity (SIL / maximum SIL of subsystems), estimation of PFH, MTTFD values and diagnostic coverage (Annexes C, H).
• Architectures and subsystems - architectural constraints, safe failure fraction (SFF), common cause failure (CCF) considerations, and diagnostic strategies (Clauses 6–7).
• Software requirements - software safety lifecycle, levels of software rigor, software verification independence and use‑case guidance (Clause 8).
• Validation and testing - validation principles, analysis and testing methods, periodic testing requirements and validation records (Clause 9).
• Parametrization and security - expanded requirements on manual/software parameterization, reference to security aspects (Subclause 6.8), and periodic testing (Subclause 6.9).
• Scope exclusions - does not cover electrical hazards from control equipment (see IEC 60204-1), general machine safeguarding, or detailed security measures (see IEC TR 63074). Design of complex programmable electronic subsystems is not within scope.

Practical applications and users

IEC 62061 is intended for:

• Machine manufacturers and integrators designing or integrating safety-related control systems for industrial machinery.
• Safety engineers performing risk assessment, SIL allocation, architecture selection and validation.
• Software developers of machine control and safety software responsible for lifecycle and verification activities.
• Certification bodies and assessors evaluating compliance of SCS against functional safety requirements.

Typical applications:

• Safety circuits for presses, conveyors, robotic cells and coordinated multi‑machine systems.
• Selection and validation of subsystems (sensors, logic evaluators, actuators) to meet required SIL and PFH targets.
• Establishing periodic testing regimes, configuration management and validation documentation.

Related standards

• IEC 61508 - overarching functional safety framework.
• IEC 60204-1 - electrical equipment of machines (electrical hazards).
• IEC TR 63074 - guidance on security aspects related to safety-related control systems.

Keywords: IEC 62061, functional safety, safety-related control systems, SIL, PFH, validation, machinery safety, IEC 61508, configuration management, periodic testing.