With Australian workplace health and safety incidents approaching 600,000 annually, the safety of our workforce is a serious concern. Here, Spiro Fkiaras, Business Manager at WEG Australia, explains how Variable Speed Drives (VSD’s) with built-in safety features deliver faster responses to safety related issues, thereby providing enhanced levels of protection for workers and equipment. 

Electric motors are at the heart of any industrial plant, powering everything from pumps and fans to conveyors and crushers, and often in harsh conditions. Wherever a fault occurs, it is imperative that these motors can be switched off in a controlled manner, in order to avoid compounding damage to equipment, product, or worst-case, to people. 

The need to improve the inherent safety of industrial machinery has driven demand for a wide variety of safety devices. However, many can add unnecessary complexity and cost to a motor control system, and in cases where available space is at a premium, additional challenges may arise.

VSD’s with built-in safety features are a great solution to this problem. VSD’s control motor speed and torque by varying the voltage and frequency of the electrical supply to the motor. Regarded highly for their energy and cost-saving potential, VSD’s can also play a significant role in machine safety.

By selecting a VSD with built in safety features, machine designers can take advantage of a full range of benefits. First and foremost, as the need for external devices is minimised and possibly negated, response times to safety issues are much faster and far more reliable. System restarts are also quicker, thereby minimising down-time and production losses.

VSD Safety features in action

WEG Australia’s CFW range of VSD’s offer the two most in-demand safety functions, Safe Torque Off (STO) and Safe Stop one time controlled (SS1-t).

When initiated, 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. Unexpected starts are also prevented. STO is essential in applications where workers may require direct contact with potentially dangerous moving parts, whether during setup, operation or maintenance. Examples include conveyors, fans, pumps, compressors and hydraulic presses.

By contrast, when the SS1-t is initiated, the VSD will decelerate the motor and driven machine to rest over a predefined period of time. It’s use therefore is of particular benefit in applications where inertial loads need to be decelerated to rest, such as with centrifuges, separators, grinders and mills before power is removed. 

This sponsored editorial is brought to you by WEG. For more information on WEG’s range of VSDs, visit

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