An ongoing discussion of machine guarding topics, including solutions assessments, regulatory compliance, gap analysis, operating efficiencies and cost savings, as well as all relevant safety standards, such as those from NFPA, ANSI, RIA, IEC, ISO and OSHA. About J.B. Titus.
Wireless Control and Wireless Safety!
December 20, 2010
Wireless technology and applications have grown rapidly over the past few years, and safe wireless communication has become part of the discussion. This is particularly important when you look back thirty years or so when communication and control bus technology was driving most of us crazy. We’ve been through the “proprietary” bus stage when suppliers found this approach superior to the “open” bus approach most large end users wanted for their applications. The technology, however, developed quite rapidly and today the distances are greater, communication can be very fast, reliability has increased dramatically, and it’s even applicable for security and safety applications. When compared to wire or cable communication and control wireless technology can be more flexible, less costly to install, and can offer operational savings.
Recently, we’ve seen wireless machine safety applications emerge and the machine safety application standards are re-writing their requirements to address the applications using this technology. In most cases so far it appears that the safe wireless communication is the same as on certified safety bus systems as you hear suppliers promoting their systems. Let’s take a moment and look under the hood.
Safe wireless (also known as safe cableless) is quite often applied to a given machine using a “zone” concept, which dramatically reduces the wireless communication distance. In one of Control Engineering’s recent most read articles, “How to choose wireless technology for industrial applications,” you can read about the importance of distance in wireless applications. It’s my opinion that one reason suppliers use a concept called zone control is to optimize the reliability of communication by creating very short distances between antennas. Yet, at the same time several more (and growing) unrelated wireless devices may also be within the wireless communication zone. These other devices may just be communicating to the general machine control architecture and have nothing to do with machine safety applications. Examples of these machine mounted devices could be temperature sensors, vibration sensors, switches, and pressure sensors…….to mention a few.
A lot of folks in industry, and me included, are wondering how industry applications standards are going to address this multiplicity of simple to complex devices. The complex devices are usually something like a cableless operator panel used for machine set-up, clearing of faults, etc. as in the blog Cableless (Wireless) Operator Panel Applications.
Has anyone come across this emerging issue and can you provide some advice how measures that can be applied to prevent unintended communication problems and possible hazards?
INTEGRATED SAFETY COULD BE YOUR OPPORTUNITY – CONSIDER IT!
As a side note – The 2011 updated NFPA 79, Electrical Standard for Industrial Machinery, was previously expected for release this month. The 2011 NFPA 79 schedule was recently modified and the current expected release date is June, 2011.
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Contact: www.jbtitus.com for “Solutions for Machine Safety”.
For more than 30 years, J.B. Titus has advised a wide range of clients on machine functional safety solutions, including Johnson + Johnson, Siemens, General Motors, Disney, Rockwell Automation, Bridgestone Firestone, and Samsung Heavy Industries. He holds a Bachelor of Business Administration degree from Oklahoma University in industrial management and an MBA from Case Western Reserve University in marketing and finance. He is a professional member of the American Society of Safety Engineers and is OSHA-certified in machine guarding. Titus is also TUV-certified as a Functional Safety Expert and serves on several American National Standards Institute, National Fire Protection Association, and National Electrical Manufacturers Association national safety and health standards committees. Reach him at jb(at)jbtitus.com and via www.jbtitus.com.
Sunday, 15-07-12 20:21
Wireless or Cableless safe control is here in the U.S. for stopping (E-Stops) and enabling. Standard wireless control stations are available from many crane and construction remote control manufacturers, but as soon as you want safety certifications you are narrowed down to 1 or 2 manufacturers. The key is dual channel outputs that interface with Category 3 or 4 safety relays.