ONLY a safety system that enhances a line's productivity is truly safe, according to Pilz Safe Automation managing director Frank Schrever.
In fact, says Frank, the best safety systems make work easier at every stage, from project planning through to operation and maintenance. Otherwise, he warns, the safety system risks being bypassed.
"Nobody wants to get hurt and no employer wants to see their staff members hurt either, but then, nobody thinks it will happen to them," Frank said.
"Injuries often occur when someone with the best intentions thinks they'll just quickly fix a hiccup on the line without needing to shut down the machinery.
"Why? Because they feel that following the correct safety procedure will slow things down and productivity will suffer - so the only way to make things really safe is to combine maximum safety with maximum efficiency."
Pilz points to the rise of programmable safety technology as the answer to increased plant availability. Wiring many conventional safety relays together can be complex, hard to fault find and time consuming to make even trivial changes.
This situation is greatly simplified with software configurable safety relays like the PNOZ Multi and the Programmable Safety Systems (PSS) with dedicated safe field bus, SafetyBUSp.
Rather than hard wiring inputs and outputs, such digital technology allows plant engineers to design safety systems with Windows-style software, making alterations swift and low cost. Replicating the system is also simplified, as the configuration can be copied from one controller to the next.
There are, however, many circumstances where guards must be legitimately bypassed. For instance, during the set-up of machine tools, such as milling machines, plant must continue to run while adjustments are made.
The European standard for milling machines, EN13128-1, stipulates that this bypass must be controlled, the speed limited and the motion only initiated by the operator via hold-to-run or two-hand control devices.
Standards Australia has slated EN13128-1 for adoption as a local standard this year.
Compliance with EN 13128-1 using conventional devices is complicated if not impossible, demanding extensive calibration of monitoring devices and difficult calculations.
The logic-based controller, the PNOZmulti, again simplifies the process, as operators key the requirements into speed monitoring modules and allow the software to make the computations. Each PNOZmulti oversees the safe standstill and/or speed of up to eight drives.
The PNOZmulti is just one component of a growing family of programmable safety devices. For engineers, the benefits are less wiring and installation work for fast, economical commissioning; troubleshooting and fault evaluation right down to I/O level; and maximum plant availability.
For employers and employees alike, the outcome is a safer and more productive workplace.