Servo drives reduce component count and respond to safety signals faster

Paul Boughton

The new L-force 9400 servo drives from Lenze offer options for drive-based safety that reduce component count, cut costs and result in faster response to safety signals.

Two plug-in safety modules cover safe stopping plus five other safety-related functions, together with communication on a safety bus.
Elements such as stop switches and light guards can be connected directly to the drive, with the resultant system meeting the requirements of IEC61508 SIL3 and the EN61508 equivalent.
Savings to the machine builder arise because, with safety built into the drive, there is no longer a need to specify a number of different safety relays and monitors for use with emergency stop switches, light curtains, guard switches and so on.
All of these can be connected directly to the drive.
Furthermore, with a Profisafe fieldbus the wiring can be simplified as well.
With the elimination of multiple safety relays and monitors, the requirement for cabinet space is reduced.
Lenze offers drive-based safety on the new 9400 series of servo drives that are rated from 0.37 to 11kW (to be extended to 400kW).
All drives can have the option of safety modules added. Because the servo drives will operate with suitable motors from any manufacturer, the concept of drive-based safety is equally applicable to machine upgrades and new builds.
The user benefits from a safety system that responds faster than existing technology.
Stopping times are therefore shorter and, for example, safety light curtains can be positioned closer to the hazard. If an operator needs regular access, the result is higher productivity.
Safety functions available include safe low speed operation, which allow an operator to enter a hazardous area with the operating speed safely limited.
The company says the Lenze safety modules can also control safe speed increments, safe operation in one direction, safe inputs and outputs, and safe parameter setting.
With the new 9400 servo drives, Lenze has achieved a new standard for drive-based safety.
Where previously options were limited to a safe disconnection of the drive, now controlled stopping, ow-speed running and other safety options are possible.
The machine builder gains with a simpler and more compact control system, while the end-user gets a machine that is safer, faster to respond, and potentially more productive.

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