Drives and Controls Magazine

Servo safety module avoids contactors

01 May, 2002

Servo safety module avoids contactors

Schneider subsidiary Berger Lahr has developed a safety module for servo and stepping motor systems which, it claims, will increase the reliability and availability of the protected systems, as well as maximising operator safety.

In the event of an emergency stop, the SAM safety monitor module decelerates the motor safely and switches off its power supply. It does this by blocking the power stage electronically, without needing contactors to disconnect the supply.

The device also monitors the behaviour of the motor when a safety guard is open. There are two modes: during "safe stops", it checks whether the motor is really idle; and during "reduced speed" operation, it monitors the motor`s speed.

A machine can be stopped at any time to allow changes to be made in the dangerous area without having to switch off the power. When the work is finished, the machine is restarted simply by closing the protective gate.

The SAM module is designed to be used with Berger Lahr`s Twin Line equipment and does not need any extra external monitoring components. It meets category 3 safety requirements.