It is the moving parts of a machine that pose a risk to machine operators and maintenance personnel. Legislation requires that these workers must be protected from risks at all times. The most effective approach is to intervene at the place in the machine that causes the movement - in other words, directly in the drive. The Lenze approach of ‘Drive-based safety’ does exactly that, meeting legal requirements but also saving money for the machine builder.
Drive-based safety consists of optional safety modules plugged into the 9400 servo drives, a new range of high performance drives covering powers from 0.37 to 370kW. The SM301 safety module now includes functionality for a safe creep speed and for safe jogging. By building safety into the drive, machine builders gain from reduced external components, simpler and faster cabling, and faster reaction to safety signals. Furthermore, there is no need for safety contactors on the power input and output to the drive, saving more cost, and making EMC compliance easier.
The option for a safe creep speed suits machines where the process must not stop. For example, ovens, or where new material has to be fed into a process. The Lenze safety module ensures that a pre-defined safe speed cannot be exceeded.
A jog process is often needed to set up a machine. The same SM301 safety module can be programmed for the maximum permissible jog speed and the maximum duration time of the jog, making the jog a safe controlled process. This function is also know as Safe Tip.
Lenze Drive-based safety modules perform to the safety standards EN945-1 Cat 3 and IEC61508 SIL3. They allow connection of active and passive safety sensors and a safe fieldbus.