Safety and functional safety
Ensuring safety is one of the key principles guiding the work of the IEC while recognizing that zero risk is not possible
Safety

The detection of smoke by a sensor triggers the activation of a water sprinkler system inside an apartment building. An enclosure is placed around a socket to protect users against accidental contact with electrical parts. Train doors automatically close and remain closed during the length of the voyage. These are just a few examples of safety measures that are utilized with electrical devices.

Safety is defined as the freedom from unacceptable risk of physical injury. Through its international standards, the IEC ensures safety is an integral aspect of devices and systems, thereby protecting people, critical infrastructure, economies and the environment. These standards can address aspects of safety that apply to many products or specifically address a single product type or industry.

The IEC has a dedicated technical advisory committee on safety (ACOS) which guides and coordinates IEC work on safety and ensures that all IEC Standards address safety issues.

The IEC operates four Conformity Assessment Systems to ensure that devices and systems comply with the requirements established in its international standards.

Functional safety
Functional safety seeks to reduce the level of risk in a device or system.

While zero risk is an unattainable goal, functional safety identifies potentially dangerous conditions that could result in harm and automatically enables corrective actions to avoid or reduce the impact of an incident. It is part of the overall safety of a system or device that depends on automatic safeguards responding to a hazardous event.

Functional safety relies on active systems that can respond to a potentially dangerous situation. Examples include the deactivation of a medical infusion pump should it malfunction or the automatic activation of an overflow valve when a certain liquid or pressure level has been reached.

Image

 

The IEC 61508 series provides functional safety standards for the lifecycle of electrical, electronic or programmable electronic (E/E/PE) systems and products. It addresses those parts of a device or system that perform automated safety functions including, for example, sensors, control logic, actuators and micro-processors.

IEC 61508 allows for the development of a uniform technical policy that can be applied for all safety systems that are electrically-based. It is a horizontal standard applicable across a wide range of industry sectors.

The standard requires the analysis of the potential risks or hazards of a given system or device. It provides categories to determine the level of likelihood of a potential hazard and the consequences should it occur. IEC 61508 defines four safety integration levels (SIL) to indicate the degree to which a system will meet its specified safety functions.

Hazard based safety engineering
Hazard-based safety engineering (HSBE) is a methodology used in the development of safety standards.

Safety considerations are an integral part of the design process with risks identified and managed in the early stages of product development.

Using this methodology, potentially hazardous energy sources are identified clearly and safeguards are put in place in order to mitigate the hazard and make a safe product. As a result, it is possible to apply HSBE to a wide range of systems and devices since the requirements are performance-based rather than prescriptive.

The HSBE methodology has become increasingly necessary with the development of electronic devices that merge audio and video technologies with IT and communications technologies.

IEC 62368-1 is a safety standard based on the HBSE methodology. It is performance-oriented, with the flexibility to be applicable to a wide range of devices, but with specific requirement and compliance criteria. 

Functional safety
An introduction to Functional safety and the IEC 61508 series.