Rockwell Touts Safe Torque Off Technology


A new safe torque off option within the Allen-Bradley PowerFlex 7000 medium-voltage drive from Rockwell Automation helps industrial manufacturers and equipment builders simplify their functional safety design and meet the demands of international safety standards. Safe torque off technology allows users to reliably remove power from the motor without removing power to the drive, enabling a faster re-start of the system after a safe state is reached.F-Rockwell-400

“Medium-voltage drives often run the most critical assets in an operation. Starting and stopping a drive repeatedly using input disconnect devices can create significant downtime and cause wear on these critical assets,” said Mark Banas, product manager, Rockwell Automation. “Medium-voltage-drive users can now help keep operations running and provide a safer work environment with certified safe torque off technology.”

When a safe torque off command is issued in the drive, from a user or a demand on the functional safety system, the PowerFlex 7000 drive immediately removes rotational power to the motor, ceasing the process. The drive stays powered and reliably monitors this “safe” state, ensuring no unintended operation of the motor is possible.

Rockwell Automation engineers designed the safe torque off option directly into the drive control, greatly simplifying setup and system design for functional safety. It works side by side with the drive’s control functions and does not require additional electromechanical components. This helps eliminate wiring needs, and lower users’ hardware inventory and installation costs.

Ideal for industrial applications, such as material-handling conveyors and grinding mills, the PowerFlex 7000 drive with safe torque off is TÜV-certified. It is also certified to Safety Integrity Level (SIL) 3 of IEC 6150, and Performance Level e (PLe), Category 3 of ISO 13849-1, the highest levels achievable for drives.

“Our customers are looking for more ways to make their operations safer and meet this growing trend toward certified functional safety. The medium-voltage safe torque off option matches what the low-voltage PowerFlex drives have been delivering,” said Banas. “Current users of the PowerFlex 7000 drive can now retrofit their systems to add the option.”

The PowerFlex 7000 drive also offers the option of enhanced torque control capabilities with Allen-Bradley TorqProve technology. Well-suited for heavy-industry applications – such as hoists, draglines, winches and test stands – the TorqProve technology can deliver 100 percent torque at zero speed. The drive’s control delivers the higher drive speed and torque response required for vertical lifting applications.

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