Larger drives offered with integral safety functions

Paul Boughton

Rockwell Automation is extending its range of Safe-off drives by offering the Driveguard safety system as an option on the Powerflex 700S AC drive.

Previously this safety functionality was only available on the Powerflex 70S model. By integrating safety features directly into its Powerflex AC drive products, Rockwell Automation is enabling manufacturers to optimise safety and productivity.

Fully compliant with the requirements of EN 954-1 Category 3, the Safe-off feature of the Driveguard system disables the motor and, consequently, the driven machine's ability to move, until it is deemed safe to do so.

The Driveguard option uses redundant signals to remove power from the output IGBT power transistors. This is achieved by a hardwired ‘enable’ signal and a positive-guided relay. The positive-guided relay also provides feedback to the safety system regarding the status of the drive. This ensures a high-integrity means of removing power from a motor and preventing it from restarting until the Safe-off option is satisfied.

It is particularly relevant in applications that are classified as medium- to high-risk. It replaces the traditional two-contactor safety system and all the associated wiring, cost and complexity that this entails.

Driveguard is already available as an option on the Allen-Bradley Powerflex 70 general-purpose AC drive. With Driveguard now available on Powerflex 700S, OEMs and end users can benefit from a high-powered drive with advanced safety features built-in.

With all the flexibility offered in this top-line drive and rated from 0.75 to 800kW at 400 to 690V, Powerflex 700S is designed to meet system integrator, OEM and end-user demands for precise, reliable high-end motor control in applications that demand accurate open-loop speed regulation. 

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