Manufacturers of mobile machines are faced with the task of upholding the legal specifications of the Machinery Directive and the Product Liability Act.
The manufacturers of sensors, actuators and control devices for the machines provide their customers with certified products for use in safety-critical applications. As the successor to the EN 954-1, the ISO 13849-1 is here the most important standard for the design of control systems in the field of machine safety.
But what happens if the planned use case is not covered by the ISO 13849-1 standard? The standard shall be applied on safety-related parts of control systems (SRP/CS) for all kinds of machines. In accordance with the EU Machinery Directive 2006/42/EC, this does not concern vehicles and methods of transport which are intended for use in public road transport. Only the machines mounted onto these vehicles (e.g. cranes, loading ramps etc.) are addressed in this standard. If there is no appropriate, specific product standard (such as the ISO 25119 for agricultural machines and municipal vehicles), manufacturers have to fall back in case of doubt on the Basic Safety Standard IEC 61508 for so-called off-highway applications.
According to DIN ISO/TR 23849:2010-05 every complex sub-system which has been designed according to IEC 61508 with the relevant SIL can be integrated as a safety-related part in a combination of SRP/CS which was designed according to ISO 13849-1 or as a sub-system in a SRECS, which was designed according to IEC 62061“ (translation by STW). This statement can in principle also be applied to the ISO 26262. Wherever today’s manufacturers of commercial vehicles shy away from using the automotive safety standard currently still limited to 3.5 tonnes, the application of the basic safety standard and the use of appropriate certified components represents the only expedient alternative. We can assume that applications can be transported with relatively little effort if they have been developed in conformance with the IEC 61508. This holds also true if the next version of the ISO 26262 will comprise “Heavy Commercial Vehicles”.
For the high-performance electrification of mobile machines, we currently do not yet have a specialist standard which can be applied to cover all components. The DIN EN 61800-5-2, for example, excludes the application of electrical high-performance drive systems with adjustable speeds in rail drive units and electrical vehicle drives. In such cases, only the application of the IEC 61508 or a specialist basic standard derived from it, such as the IEC 62061, remains as a valid option.
As a supplier of solutions for mobile machines, utility vehicles and special machines, STW already shoulders the increased development expense for certification in accordance with the Basic Safety Standard IEC 61508. In this way we can provide our customers with the option of securing their investments and applying our products in their applications long-term.