August 2021

46 n INSIGHT July/August 2021 www.drivesncontrols.com Drive-based safety offers many benefits S afety installations are increasingly being implemented within drives systems rather than having to use dedicated safety equipment. The advantages for end-users include: reductions in wiring and the amount of hardware that needs to be installed; savings in space inside cabinets; and more flexible safety concepts that make it easier to upgrade machine safety at a later stage. To implement a drive-based safety system, users first need to perform a risk analysis and to minimise the risk in accordance with the appropriate standards. They can then design the safety functions and select their components, using, for example, the safety evaluation function in Siemens’ TIA selection tool. Following commissioning of the drive, a safety acceptance test should be performed. Here, a tool such as Sinamics Startdrive Advanced can provide assistance and generate protocols automatically. The drive does not need to be connected to a higher-level system to implement a drive-based safety system. Various control concepts are possible, ranging from simple local safety control via the drive’s terminals, to using an F-PLC with a Profisafe connection. The Simatic LDriveSafe library allows safety integrated functions to be controlled easily via Profisafe. Version 17 of TIA Portal implemented a new function known as safety activation testing. Since version 15, it has been possible to perform a safety acceptance test that validates the correct safety parameterisation for the integrated drive safety functions. This could, for example, check and test whether the braking ramps, and the limitations and fault reactions, have been set correctly. The new safety activation test validates the complete safety control system from sensors to actuators. It is now possible to test, and gain a clear understanding of, whether: n every drive selects the correct safety function when a safety sensor is activated; n all safety functions are realised to minimise risks; and n whether there are any wiring errors for the safety sensors. Saving time and money Depending on the safety functions required, users can save a lot of money by using the safety functions built into a drive rather than relying on conventional external safety systems. Using traditional drives without built-in safety requires additional hardware safety components such as safe speed-monitoring devices. For a drive with integrated safety functions, all that is needed is a safety software licence for the drive. The reduced Building safety functions into variable-speed drives offers many attractions over using traditional external hardware and software. Matt Handley, Siemens product manager for continuous motion, explains to Drives & Controls how drive-based safety works, and highlights its benefits. One way of implanting drive-based safety is locally via the drive’s terminals