Lenze 9400 servo drives feature optional plug-in safety functionality such as Safe Stop 2, Safe Operating Stop and Safe Speed Monitor. Previously those required an expensive encoder feedback option to meet the EN 61508 and EN ISO 13849-1 safety standards, but now the Lenze SM301 safety module can accept a single resolver input and achieve PL d / SIL 2 safety levels, resulting in a significant cost saving for machine builders.
Generally the most critical safety components in a machine design are the drives – which is where dangerous movement is typically be initiated. Recent years have seen advances to integrate safety functions within the drive, which can simplify and reduce the cost of machine builds. Direct handling of sensor signals in the drive has reduced component count and simplified the process of compliance with the safety standards. However, the full cost benefits have been held back by a requirement to use special encoders for feedback, typical SinCos types that are both expensive and delicate.
Now Lenze has certified the SM301 safety module to operate with a single resolver feedback. As resolvers are simple, robust and a standard option for Lenze synchronous and asynchronous servo motors, this new development leads to a sharp reduction in costs. Also feedback from a single standard incremental encoder is possible. Both options comply with standards PL d of EN ISO 13849-1 and SIL 2 of IEC 61508. Alternatively, a higher safety level of PL e and SIL 3 can be achieved by adding a second incremental encoder.
Cost savings from resolver feedback apply to seven motion functions:
- Safe Stop 2
- Safe Operating Stop
- Safely Limited Speed
- Safe Maximum Speed
- Safe Speed Monitor
- Safe Direction
- Safely Limited Increment
The SM301 plug-in module is readily available for the Lenze 9400 servo drives and also allows use of the PROFIsafe safety bus.
Follow the link for more information about drive-based safety using 9400 series servos.