SIL Certification Technical Services

Based on standards including IEC 61508, IEC 61511, IEC 61513, ISO 13849-1, IEC 62061 and IEC 61800-5-2, SIL certification is a third-party assessment, verification and certification to evaluate and confirm the Safety Integrity Level (SIL) or Performance Level (PL) of safety-related equipment. Functional safety certification mainly covers FSM document assessment for safety device development processes, hardware reliability calculation and evaluation, software assessment, environmental testing, EMC electromagnetic compatibility testing and other items.

CENELEC (European Committee for Electrotechnical Standardization) is one of the three major European standardization organizations, responsible for European standardization in the electrotechnical field. Together with ETSI for telecommunications standardization and CEN for other technical fields, CENELEC forms the European standardization system.

SIL certification is divided into four levels: SIL1, SIL2, SIL3 and SIL4, covering both product and system levels. Among them, SIL4 has the most stringent requirements. Main Standards for SIL Certification

IEC 61508:

Functional safety of electrical / electronic / programmable electronic safety-related systems

The IEC 61508 standard specifies basic safety requirements for normal system operation and failure prediction capabilities. These requirements cover general safety management systems, specific product design and process design in compliance with safety regulations, aiming to avoid both systematic design failures and random hardware failures.

Core objectives of IEC 61508:

01
Provide a systematic approach for lifecycle safety supervision of all safety-related system components, including software and hardware;
02
Offer methods to define safety functional requirements for safety-related systems;
03
Establish fundamental standards directly applicable to all industrial sectors, and guide the formulation of standards in other fields to ensure consistency in basic concepts, technical terms and mandatory safety function requirements;
04
Encourage operators and maintenance departments to adopt computer-based technologies;
05
Build a standardized and coordinated overall standard framework.

IEC 61511:

IEC 61511 is a dedicated functional safety standard for safety instrumented systems in the process industry. Released after the basic functional safety standard IEC 61508, its domestic equivalent standard is GB/T 21109. In the process industry, safety instrumented systems are used to perform safety instrumented functions, and IEC 61511 defines the required safety integrity and performance levels for such instruments.

The SIL level is a globally recognized indicator for verifying safety-related functional performance. For the process control industry, core international standards include IEC 61508 (the foundation for designing and operating safety instrumented systems). IEC 61511 focuses on process control applications, guiding designers to conduct system design in combination with IEC 61508.

ISO 13849-1:

Safety of machinery — Safety-related parts of control systems — Part 1: General design principles

The updated ISO 13849-1 officially took effect at the end of 2011, marking a new milestone in machinery functional safety. Compared with previous deterministic system requirements, it adds quantitative assessment of system failure probability, enabling comprehensive safety evaluation from components to complete systems. It also provides designers with quantifiable design indicators such as required performance level (PLr), mean time to dangerous failure (MTTFd), diagnostic coverage (DC) and common cause failure (CCF) prevention, solving the limitation of qualitative safety judgment in the old EN 954-1 standard.

The new standard delivers optimized safety assessment solutions for emerging control technologies, improving the safety level of increasingly complex mechanical control systems. It ensures production safety and high efficiency, helps enterprises enhance overall efficiency, productivity and flexibility, maintains continuous operation, reduces unplanned downtime, and cuts development, operation and maintenance costs. Early adoption helps machinery manufacturers gain competitive advantages in the market.

IEC 62061:

Safety of machinery — Functional safety of safety-related electrical, electronic and programmable electronic control systems

Both IEC/EN 62061 and EN ISO 13849-1:2008 cover safety-related electrical control systems and deliver equivalent safety performance and integrity. Though adopting different methodologies, both standards target applicable application scenarios. EN ISO 13849-1:2008 specifies limitations for complex programmable technologies, defining PLd as the maximum performance level in such cases.

IEC/EN 62061 provides solutions for complex safety functions implemented by non-traditional system architectures, while EN ISO 13849-1:2008 offers simplified approaches for conventional safety functions. A key difference lies in application scope: IEC/EN 62061 is limited to electrical systems, whereas EN ISO 13849-1 covers pneumatic, hydraulic, mechanical and electrical systems. Core evaluation parameters include PFH, MTTF, DC and SFF.

IEC 61326-3-2:

Electrical equipment for measurement, control and laboratory use — EMC requirements — Part 3-2: Safety-related systems and equipment performing safety functions (Functional Safety)

IEC 61326-3-1 and IEC 61326-3-2 specify additional immunity requirements for safety-related equipment, covering extreme electromagnetic conditions that may occur in various environments. Tests simulate harsh electromagnetic interference under actual operating conditions, such as transient pulses for digital circuit and signal transmission. To improve the credibility of EMC immunity for high SIL-level equipment, stricter test conditions are required, including increased pulse quantity, extended test duration and higher test levels. For example, SIL3-rated equipment requires a 4kV EFT test with a duration five times longer than the basic standard requirements.

ISO 26262:

Functional safety for road vehicle system design

Developed to clarify and standardize safety-related functional definitions, ISO 26262 is derived from the fundamental functional safety standard IEC 61508. Tailored for automotive-specific electrical, electronic and programmable components, it is an international standard to improve the functional safety of automotive electronic and electrical products. Widely recognized by vehicle manufacturers and component suppliers, it has been fully implemented in product development.

Based on IEC 61508, ISO 26262 defines safety specifications for electrical and electronic systems. A core challenge in vehicle design is the pre-assessment of potential hazards and risks and the adoption of targeted mitigation measures. The standard mandates hazard and risk analysis at the initial stage of product development.

The automotive industry widely adopts high-performance electronic devices for vehicle safety control. ISO 26262, jointly formulated and recognized by global mainstream automakers, standardizes the design requirements for automotive electronic components, software and hardware. The implementation of ISO 26262 reduces vehicle risks and accident hazards, enhancing the international competitiveness and market adaptability of the domestic automotive industry.

IEC 61800-5-2:

Adjustable speed power drive systems — Part 5-2: Functional safety requirements

IEC 61800-5-2 defines safety functions for integrated safety drives, including a series of stop functions:

1. Safe Torque Off (STO);

2. Safety Stop 1 (SS1) / Safety Stop 2 (SS2)

3. Safety Operation Halt

This standard also specifies monitoring functions, including safe acceleration limit, safe travel limit, safe direction limit, safe speed limit, safe torque/force limit, safe position limit and motor temperature safety monitoring.

IEC 61800-5-2 specifies functional safety requirements for safety encoders, safety decoders, AC servo systems, servo drives and servo motors. Compliance enables devices to support safety functions such as STO and SS1 to prevent unexpected startup. This standard has been adopted as the national standard GB/T 12668.5.2, managed by the TC60/SC1 domestic standardization committee.

EN 50156

Industrial communication networks — Functional safety communication profiles

Core contents of this standard:

01
Specify basic principles for safety-related data communication in accordance with IEC 61508, including provisions for transmission errors, countermeasures and data integrity assurance
02
General specifications applicable to multiple technical implementations
03
Independent description of functional safety profiles for various communication protocol families
04
Define multiple safety communication layers as supplementary service profiles for IEC 61784-1 and IEC 61158 series standards

EN 50126

Railway applications — Specification and demonstration of Reliability, Availability, Maintainability and Safety (RAMS)

This standard defines RAMS (Reliability, Availability, Maintainability and Safety) for railway systems, and specifies management requirements for each phase of the safety lifecycle. As a key indicator of system service quality, RAMS is realized through design concepts and technical measures throughout the entire lifecycle.

EN 50128

Railway applications — Software for railway control and protection systems

It classifies software Safety Integrity Levels (SIL) for railway control and protection systems, and formulates targeted specifications for different safety requirements. It defines standardized requirements for the entire software lifecycle, including software requirements, testing specifications, architecture design, verification & validation, hardware-software integration, quality assurance and technical documentation.

EN 50129

Railway applications — Safety-related electronic systems

It adopts the IEC 61508 safety lifecycle concept for safety management, requiring full-process safety design, assessment and verification for safety-related system components. This mechanism reduces human errors and lowers system failure risks in railway applications.