Safe torque off suits medium-voltage drive

A new option within the Allen-Bradley PowerFlex 7000 medium-voltage drive helps 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.

“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,” says Rockwell Automation Product Manager Mark Banas. “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 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.

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. Safety triggers—such as push buttons or light curtains—wire directly to the drive, removing the need for additional hardware.

The PowerFlex 7000 drive now also offers the option of enhanced torque control capabilities with Allen-Bradley TorqProve technology. Well-suited for heavy-industry applications, 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. —