6-1
Safe Torque Off
AC30V series Variable Speed Drive
Chapter 6
Safe Torque Off SIL3/PLe
General Information
THIS EQUIPMENT IF USED INCORRECTLY IS POTENTIALLY DANGEROUS. THEREFORE UNDER NO CIRCUMSTANCES
SHOULD IT BE USED BEFORE THESE INSTRUCTIONS HAVE BEEN READ AND UNDERSTOOD BY THE END USER WHO
SHOULD BE APPROPRIATELY QUALIFIED TO OPERATE THE EQUIPMENT.
This section provides general information about Safe Torque Off (STO).
Two safety functions can be implemented with the AC30V: STO and Safe Stop 1 (SS1). In order to meet all aspects of STO and SS1, an external safety
control unit should be used.
To implement Safe Stop 1 (SS1), the external safety control unit causes the drive to decelerate to rest. Once at rest, it invokes STO in the AC30V.
Please refer to EN61800-5-2:2007 para 4.2.2.3 for the formal definitions.
It is the user’s responsibility to:
1) Risk assess the machine.
2) Design, implement and assess an appropriate solution for each application to meet all relevant safety requirements.
Note: STO is an electronic inhibit intended for use during normal operation of the machine. It is not intended for use during machine maintenance,
repair, replacement or other similar activities. For these activities recognised electrical power isolation devices and lock-off procedures should be used.
The AC30V STO function is a factory-fitted and factory-tested feature. See the section “Safety Warnings and Limitations” on page 6-18.
