Controls and drive technology Components under the aspect of functional safety back to current issue Thomas Möller, freelance editor, Offenbach Thomas Möller Certified products with the Test sign for “functional safety” warrant safety and reliability in the machinery industry and thus a clear competitive benefit. The US certification company Underwriters Laboratories now sets accents on the North-American market as well, awarding its Functional Safety Listed test sign in Germany for the first time — to a Siemens frequency converter. Functional safety also mainly depends on defectfree function of the microelectronics and software. If a company is able to document its dedication in the area of functional safety by exhibiting the test sign for this area, this is an additional sales argument for the products certified accordingly. European companies hold an internationally pioneering role in the area of functional safety. Functional safety is not as present yet in the awareness of the North-Ameri- can market. To set accents on this market, Siemens had its frequency converters certified by the US company Underwriters Laboratories (UL): It is the first Functional Safety Listed test sign awarded to a German product by UL. Certification as a strategic project The Sinamics G110D by Siemens is a local frequency converter of protection class IP65 for setup without control cabinets. It can be installed close to the motor and offers standardised plug connections. Dr. Thomas Winkovich, responsible Functional Safety Manager at Siemens, explains why this frequency converter was particularly suitable for a certification project with UL in Germany: “The Sinamics G110D is a development that we can sell separately as well. Other projects here are often included in complete systems, and new modules like this are then integrated into the present system certificate. Therefore, we have used the opportunity to have the G110D tested by UL. For us, this Functional Safety certification of the frequency converter also had the character of a strategic project. We were able to explain our way of thinking and our processes for functional safety to UL and to consider their suggestions.” AUTOMATION TECHNOLOGIES 3/2014
Controls and drive technology Dr. Thomas Maier, Primary Designated Engineer Functional Safety and thus responsible for the project at UL in Germany, notes that functional safety does have a certain tradition at UL: “Even in the 1990s, UL developed test standards in the area of functional safety. However, we have now newly expanded our functional safety programme by a special FS test sign in 2010.” The functional safety audit at UL assesses how well the applicable norms and standards regarding reliability and effectiveness of safety-technical systems are met and complied with. UL reviews the input parameters of a device and determines whether its reaction is within the index data range. This review includes the evaluation of software, hardware, environmental factors and the underlying lifecycle process of functional safety. UL inspected the frequency converter according to the four following international safety standards: IEC 61508:2010, ISO 13849-1:2006, IEC 61800-5- 2:2007 and NFPA 79. Certification process in detail In the first step, there was a kick-off meeting between UL and Siemens: This was the first phase in the certification process. All parties are working to ensure that the product meets the basic features required by the respective standards in the design phase already. The schedule and the most important stages are talked about and prototypes are discussed. Having this kick-off in the research and development phase already avoids the necessity of later changes and increases the effectiveness and economic efficiency. The second phase comprises a pre-audit and initial evaluation. This audit also should take place during development of the new product. The engineers of the certification company perform a gap analysis on site for hardware, software and the quality systems in respect of functional safety. It is based on the customer‘s product concept and procedures. Preaudit and initial evaluation are meant to increase the probability of a successful certification audit. “UL is committed to neutrality and must not render any consulting services,” says Maier. “But we can always inform the customer of our review results and help prevent mistakes even in the development phase.” The actual certification audit takes place in the third phase. UL reviews correspondence of the quality management system for functional safety with the intended standards regarding the safety levels. In the case of G110D, the actual tests took place at Siemens in English Congleton. The tests are followed by assessment of the development and test documentation, as well as performance of the tests. The fourth phase comprises of regular follow-up audits for products that have already gone through the certification process and that bear the UL test sign for functional safety. The certification company ensures integrity of the test sign by a two-level control programme. This includes quarterly audits by an UL inspector and an audit of the quality system for functional safety every three years. Test seal offers competitive benefits UL supports understanding and acceptance of the principles of functional safety in the USA and in Canada with its work and service portfolio. “German companies will benefit from cooperation with UL to receive the Functional Safety Listed test sign on the growth market of North America,” says Maier. “The importance of functional safety is growing there – and UL supports this trend: by spreading information, by our certification services and also by the marketing-effective functional safety listed test sign. Functional safety is increasingly becoming a global competitive benefit.” Photographs: teaser fotolia/ate www.ul.com Local frequency converter Sinamics G110D in protection mode IP65 About Company name: Underwriters Laboratories LLC Headquarters: Northbrook, IL, USA Employees: ca. 10,700 Products: certification, validation, inspection, training AUTOMATION TECHNOLOGIES 3/2014
