Why Functional Safety Evaluation Is Important

08 Jun 2026

And Why it Applies to Far More Systems than Many Engineers Realize

When engineering teams hear the term ‘functional safety’, many immediately think of IEC 61508 and familiar concepts such as Safety Integrity Levels (SIL). However, functional safety is not limited to one standard or certification scheme. It is a broad engineering discipline applied across many sectors and industries, focused on ensuring that safety-related control functions effectively reduce risk to people, assets and the environment.

These principles appear across many different safety standards, even when the term functional safety is not explicitly used. This is particularly important today, as many modern products and systems – from industrial machinery and automation systems to household appliances and energy storage equipment – rely heavily on electronic control systems and software to perform safety functions.

When those systems fail, the consequences can be catastrophic, which is why functional safety evaluation plays such an important role in modern safety engineering.

Functional Safety Exists Across Multiple Standards

While IEC 61508 is largely considered the foundation of functional safety engineering, similar principles appear in a wide range of standards and regulatory frameworks. For example, in the IEC ecosystem, standards such as IEC 61508 and IEC 62061 introduce structured safety lifecycles, hardware reliability analysis, and SILs. In machinery applications, ISO 13849 takes a slightly different approach by using Performance Levels (PL), system architecture categories, and diagnostic coverage to demonstrate that control systems can reliably reduce risk.

Functional safety concepts are also embedded within several widely used North American standards, including:

• UL 60730 / IEC 60730 - Automatic electrical controls
• UL 991 - Safety-related controls employing solid-state devices
• UL 1998 - Software in programmable components
• CSA C22.2 No. 0.8 - General requirements for control equipment

Although these standards may not explicitly reference SIL or Performance Levels, they still require manufacturers to demonstrate that control systems behave safely during fault conditions, abnormal operation and software failures.

Functional Safety Within Product Safety Standards

Functional safety evaluation is increasingly a required consideration within many ‘product’ safety standards. Demonstrating compliance with the product standard therefore requires evidence that functional safety requirements have also been sufficiently demonstrated.

A good example is UL 9540 for energy storage systems.

Energy storage systems rely heavily on electronic control systems such as Battery Management Systems (BMS) to maintain safe operation. These control systems are responsible for monitoring system conditions and initiating protective actions when unsafe conditions occur.

Typical safety-related BMS functions may include:

• Over-charge protection
• Over-discharge protection
• Temperature monitoring and shutdown
• Fault detection and system isolation

To demonstrate compliance with UL 9540, manufacturers must show that these control systems operate safely even when faults occur. As a result, functional safety evaluation becomes a critical component of demonstrating compliance with the overall product safety requirements.

Why Functional Safety Evaluation Matters

At its core, functional safety evaluation exists to answer a fundamental engineering question:

Can this system be trusted to behave safely when something goes wrong?

Safety functions are typically implemented through combinations of sensors, programmable controllers, software logic and electronic components. However, simply implementing a safety function does not guarantee that it will operate correctly when faults occur.

Functional safety evaluations examine the system architecture, diagnostics, reliability characteristics and development processes to determine whether the safety function can actually deliver the required level of risk reduction.

In practice, this type of evaluation helps organisations to:

• Confirm that safety functions genuinely achieve their intended purpose
• Identify architectural weaknesses or diagnostic limitations early in development
• Demonstrate compliance with applicable safety standards
• Support certification, regulatory approval and market acceptance

Ultimately, functional safety evaluation provides confidence that safety-critical systems will behave correctly when faults occur.

Functional Safety Is a Lifecycle Discipline

Functional safety is not a single test or certification activity. It is a lifecycle discipline that spans the entire system development process.

The process begins with hazard and risk analysis, where potential hazards are identified and the level of risk reduction required from safety functions is determined. From there, safety requirements are specified, defining what the safety-related system must do in order to mitigate those risks.

These requirements guide the system architecture design, as well as the development of both hardware and software components that implement the safety functions. Throughout development, the system must then undergo verification and validation activities to confirm that the safety requirements have been correctly implemented and that the system behaves safely under expected operating and fault conditions.

Functional safety evaluation plays a critical role throughout this lifecycle. It ensures that the safety objectives identified during the initial risk analysis remain aligned with the engineering implementation as the system design evolves.

Final Thoughts

As modern systems become increasingly automated and software-driven, demonstrating the safety of electronic control systems becomes more complex.

Functional safety evaluation provides the structured engineering framework needed to ensure that safety-related systems:

• achieve the required level of risk reduction
• behave safely under fault conditions
• comply with recognised safety standards
• support safe operation throughout their lifecycle

Whether operating under functional safety standards, machinery safety frameworks, control system standards, or product safety standards, the underlying objective remains the same: ensuring that safety functions perform reliably when they are needed most.