~ WEG’s VSDs with built in safety features offer safer machinery with a smaller footprint ~
Globally, there are approximately 340 million occupational accidents each year, according to the United Nation’s International Labour Organisation. With lives at risk, the safety of industrial machinery is a serious business. Here, Marek Lukaszczyk, European and Middle East marketing manager at motor and drive manufacturer, WEG, explains how variable speed drives (VSDs) with built-in safety features can be used to protect workers and equipment while reducing the number of safety devices necessary — saving space and cost.
Motors are at the heart of many plants, powering everything from compressors to centrifuges — often running continuously and in harsh conditions. With such hard-working equipment, no matter how reliable, it’s almost inevitable that, at some point, something will go wrong. Wherever a fault occurs in a production line, it’s imperative that any motors can be switched off safely, in a controlled manner, to avoid compounding the damage to equipment, product, or worst-case scenario, people.
That’s why any industrial machinery should be connected to safety devices. However, multiply that by all the different pieces of equipment found within a large factory and you can see how costs easily begin to rise, and cabinet space begins to shrink.
VSDs with built-in safety features are a great solution to this problem. VSDs control motor speed and torque by varying the frequency and voltage of the electrical current being fed into the motor. Prized for their energy and cost-saving potential, VSDs can also play a role in machine safety.
Safer and streamlined
By choosing a VSD with built in safety features, manufacturers can take advantage of a range of benefits. First and foremost, by not using an external electromechanical safety device, safety responses will happen faster — making the system safer — and system restarts by the VSD will be quicker too, minimising any delays to production.
Using VSDs with built-in safety features also means less safety components to install, resulting in an installation that’s easier and cheaper, a benefit that extends to maintenance too. It also saves space in cabinets, making machinery more compact.
In these VSD models, redundant input terminals are dedicated to safety features, including external failure monitoring, so none of the functionality of the VSD is lost. Plus, even in the event of other failures in the VSD, the safety procedures will remain active — safety always has the highest priority.
Manufacturers looking to install VSDs with built-in safety features in their facilities need to get them certified by an unbiased third party in accordance with international safety standards.
Safety features in action
WEG has updated its reliable and robust CFW VSDs with the two most popular safety functions, safe torque off (STO) and safe stop one time controlled (SST1-t).
The STO function makes it impossible for the motor shaft to produce any torque, meaning the motor will coast to a stop if it is rotating, and preventing any unexpected start-ups. This feature is essential for times when workers need direct contact with dangerous moving parts, whether during set up, operation or maintenance. It’s particularly useful in relation to conveyors, fans, pumps, compressors and hydraulic presses.
By contrast, when the SS1-t is triggered, there will be a pre-defined delay time, during which the VSD will gradually decelerate the motor before the power is cut off. It’s needed for applications where inertial loads need to be slowed down before coming to a stop, such as centrifuges, mixers, dissolvers and mills.
Both safety functions are available in a single plug-in module, easily installed with simple wiring and programming.
By choosing VSDs with built-in safety functions, manufacturers can take advantage of a faster response time and reduced footprint, meaning safer and smaller machines. With so many workplace accidents taking place each year, these VSD models mean manufacturers can rest assured they’ve done the most they can to protect their workers and equipment, without losing profit.
For more information on VSDs with built-in safety features, click here. Or, to discover WEG’s CFW range of VSDs, follow this link.
