160 Rockwell Automation Publication 2198-UM005C-EN-P - February 2022
Chapter 9 Kinetix 5300 Safe Torque Off Function
Category 3 Requirements According to ISO 13849-1
Safety-related parts are designed with these attributes:
• A single fault in any of these parts does not lead to the loss of the safety
function.
• A single fault is detected whenever reasonably practicable.
• Accumulation of undetected faults can lead to the loss of the safety
function and a failure to remove motion producing power from the
motor.
Stop Category Definition
Stop Category 0 as defined in IEC 60204 or Safe Torque Off as defined by
IEC 61800-5-2 is achieved with immediate removal of motion producing power
to the actuator.
Performance Level (PL) and Safety Integrity Level (SIL)
For safety-related control systems, Performance Level (PL), according to ISO
13849-1, and SIL levels, according to IEC 61508 and IEC 62061, include a rating
of the systems ability to perform its safety functions. All of the safety-related
components of the control system must be included in both a risk assessment
and the determination of the achieved levels.
Refer to the ISO 13849-1, IEC 61508, and IEC 62061 standards for complete
information on requirements for PL and SIL determination.
Description of Operation The Safe Torque Off (STO) feature provides a method, with sufficiently low
probability of failure, to force the power-transistor control signals to a disabled
state. When disabled, or any time power is removed from the STO inputs, all of
the drive output-power transistors are released from the ON-state. This results
in a condition where the drive performs a Category 0 Stop.
Under normal operation, the STO inputs are energized. If either of the STO
inputs are de-energized, then all of the output power transistors turn off. The
Safe Torque Off response time is less than 12 ms.
IMPORTANT In the event of a malfunction, the most likely stop category is Stop
Category 0. When designing the machine application, timing and distance
must be considered for a coast to stop. For more information regarding stop
categories, refer to IEC 60204-1.
ATTENTION: Disabling the power transistor output does not provide mechanical
isolation of the electrical output that is required for some applications.
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