Offer SIL Certification and SIL Grading Consultancy Services - Shenzhen Zhongnuo Testing Technology Co., Ltd.
SIL 2 and SIL 3 certifications are two different levels. According to international certification standards, the SIL 3 level is higher than the SIL 2 level. Specifically, it is expressed as:
An actuator of SIL1 level must have a failure probability controlled at ≥10-6 to <10-5 during average continuous operation per hour.
SIL2 is from ≥10^-7 to <10^-6. SIL3 is from ≥10^-8 to <10^-7.
Of course, the requirements for a SIL3 level are significantly higher than those for a SIL2 level.
Most products currently meet the requirements with SIL2 or SIL3 certification levels.

What is the failure rate of SIL certification?
During the SIL certification process, a concept we often mention is the equipment failure rate, which is a core term in SIL certification. It can be said that without determining the failure rate, the SIL certification is incomplete and not comprehensive. So, what exactly is the concept of failure rate?
Firstly, to understand failure rates, we must grasp what is meant by failure. According to the definition in GB/T 20438.4, which is also aligned with IEC 61508, failure is "the termination of a functional unit's ability to perform a required function, or the operation of the functional unit in a non-required manner." A more intuitive understanding could be: normally, y=f(x), but upon failure, it becomes y≠f(x), where f() represents the pre-set function, and y symbolizes our safety expectations. This also explains why "function" is the same word used for both functions and functions in English.
This statement might be too formal and not easily understood by the general public. So, speaking in more colloquial terms, let's liken it to a lighting system. If the lighting system isn't illuminating or isn't doing so as per our set requirements, it's considered to be malfunctioning.
So said, everyone may know that when a product does not function according to our set requirements, we can say it has failed. Then, what is the probability of this failure? This is the failure rate.
Understood what failure is, we can then categorize the types of failure. In the concept of functional safety, failures can be divided into two main categories based on their generation cause: systematic failure and random hardware failure. Among them, random hardware failure is quantifiable. The calculation process of PFDavg is based on a probabilistic analysis of random hardware failure.
In the SIL certification process, we analyze the theoretical models of products and utilize the experience data from their market sales to determine the failure rates, which, when combined with other parts of the SIL certification, form a comprehensive system to ensure the reliable and safe execution of safety functions.

The standard for SIL Safety Integrity Level certification primarily is:
1. IEC61508—Establishes fundamental safety requirements for both conventional system operation and fault prediction capabilities. These requirements encompass general safety management systems, specific product design, and process design that meets safety requirements, aiming to prevent both systematic design failures and random hardware failures.
2. IEC61511 - A functional safety standard specifically for safety instrumented systems in the process industry, which is a domain standard released by the International Electrotechnical Commission (IEC) following the foundational functional safety standard IEC61508. The coordinating standard for IEC61511 in China is GB/T 21109.
3. ISO 13849-1—Comprehensive safety assessment from components to systems. Additionally, this standard provides designers with more quantifiable design implementation methods.
4. IEC62061—Standard in the field of electrical systems.
5. IEC61326-3-2 – Specifies additional requirements for immunity levels of safety-related equipment, including low-probability end-of-life scenarios that may occur at the site.
6. ISO 26262 – Primarily focused on specific electrical devices, electronic equipment, and programmable electronic devices within the automotive industry, specifically designed for automotive applications, aiming to enhance the functional safety of automotive electronics and electrical products.

The SIL assessment covers the following content:
1. System Evaluation
– Risk analysis, refer to risk classification chart (ASIL/SIL/PL)
Review of specifications and safety requirements
Concept and Design Analysis
– Verification and Confirmation
2. Software and Tool Evaluation
– Testing of development tools and other communication protocols
Structural Analysis
3. Hardware Assessment
Probability Analysis
Failure Analysis
4. SIL Certification
Components and System SIL Certification
- Safety Process SIL Certification
- Granting of system, semiconductor, development tools, and process testing symbols
5. Additional Services
Risk Applicability and Risk Analysis
- Test and evaluate hardware and software for security during the development process
Conceptual Assessment (Initial Inspection)
Functional Safety Management (FSM)
- Security, reliability, and availability analysis
Qualified Assessment Meeting Relevant Safety Standards
These services are aimed at manufacturers of components, subassemblies, and systems for the automotive industry (including electric vehicles), elevators, power plants, machinery, and process sectors. They support the fulfillment of due diligence obligations and ensure the correct application of the standard, contributing to improved safety levels and helping to minimize residual risks. Standards such as IEC61508 and others can be integrated into existing quality management systems in a beneficial manner. The implementation of regulations and provisions contained in the standards provides a reliable basis for decision-making, particularly regarding safety structures, testing procedures, and tools. Development outputs can be validated at an early stage, while also reducing development time and costs. Additionally, certification enhances the image and elevates the company's profile in the competitive market.
SIL certification is a third-party evaluation, verification, and certification based on standards such as IEC 61508 (GB/T 20438), IEC 61511 (GB/T 21109), IEC 61513, IEC 13849-1, IEC 62061, IEC 61800-5-2, etc., to assess and confirm the Safety Integrity Level (SIL) or Performance Level (PL) of safety equipment. Functional safety certification primarily involves assessments of document management (FSM) for the development process of safety equipment, hardware reliability calculations and assessments, software evaluations, environmental testing, and EMC electromagnetic compatibility testing. SIL certification is divided into four levels: SIL1, SIL2, SIL3, and SIL4, covering both product and system levels, with SIL4 having the highest requirements.