QSHT 5700 Inverter Safe Torque-off Function
Introduction
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MagneMotion
Rockwell Automation Publication MMI-UM007F-EN-P - September 2020
Safe Torque-off Feature
The safe torque-off (STO) design, when used with suitable safety components such as output
signal switching devices (OSSD) or dry-contact devices, provides protection according to ISO
13849-1 (PL e), according to IEC 61508, IEC 61800-5-2, and IEC 62061 (SIL CL 3). All
components in the safety system must be chosen and applied correctly to achieve the desired
level of operator safeguarding.
The MMI-HT-C2198-D032 STO circuit is designed to turn off all of the output-power transis-
tors when the STO function is requested (hardwired signal). Use the MMI-HT-C2198-D032
circuit in combination with other safety devices to achieve a Stop Category 0 stop as
described in
, and protection-against-restart as specified
in IEC 60204-1.
ATTENTION:
The safe torque-off (STO) feature is suitable
only for performing mechanical work on the drive system or
affected area of a machine. It does not provide electrical
safety.
SHOCK HAZARD:
In the safe torque-off state, hazardous
voltages can still be present at the QSHT 5700 inverter. To
avoid an electric shock hazard, disconnect power to the sys-
tem and verify that the voltage is zero before performing any
work on the inverter.
ATTENTION:
Personnel responsible for the application of
safety-related programmable electronic systems (PES) shall
be aware of the safety requirements in the application of the
system and shall be trained in using the system.
ATTENTION:
Linear drives produce thrust not torque.
Since Safe Torque-off (STO) is an industry recognized term
for this safety function that term is used here. All references
to torque actually reference the thrust produced by the motor.