Safe Torque Off (Sto) Function; Functional Safety - Omron OMNUC G5 R88M-K series User Manual

7-1 Safe Torque OFF (STO) Function

7-1 Safe Torque OFF (STO) Function
The safe torque OFF (hereinafter referred to as STO) function is used to cut off the motor
current and stop the motor through the input signals from a safety equipment, such as a Safety
Controller or safety sensor, that is connected to the safety connector (CN8).
When the STO function is operating, the
output (READY) to go into the safety status.
 When using the STO function, be sure to execute a risk assessment of the equipment to confirm
that the system safety requirements are met.
 There are following risks even when the STO function is operating. Be sure to take safety into
account as part of the risk assessment.
7
 Do not use EDM output for other than the failure monitoring function. The EDM output signal is
not a safety output.
 The dynamic brake and external brake release signal output are not safety-related parts. Make
sure to design the equipment not to be dangerous even if the external brake release fails during
the STO status.
 When using the STO function, connect an equipment that meets the safety standards.
 The PFH value is 2.30 10
The STO function meets the following safety standards.

Functional Safety

Standard
Functional
safety
7-1
Precautions for Safe Use
• The motor runs if external force is present (e.g., force of gravity on the vertical axis, etc.). If
holding is required, implement appropriate measures, such as providing external brakes. Take
note that the brakes for the
cannot be used for control.
• Even if there is no external force, when Stop Selection for Alarm Detection (Pn510) is set to
free-run (with the dynamic brake disabled), the motor operates as free-run and the stop
distance is long.
• In case of internal failure of components, the motor may operate in the range of up to 180
degrees of electrical angle.
• The power supply to the motor is cut off by the STO function, but the power supply to the
will not be cut off nor electrically insulated. For
Drive
power supply to the
Servo Drive
8
Product
AC Servo Drive
OMNUC G5-Series AC Servo Drives Users Manual (Built-in MECHATROLINK-II communications type)
turns OFF the servo ready completed
Servo Drive
Servo Drive with brakes are used for the holding purpose only, and
through another means.
.
Applicable standards
EN954-1 (Cat.3)
ISO13849-1 (PLd)
EN61508 (SIL 2)
EN62061 (SIL 2)
EN61800-5-2 (STO)
IEC61326-3-1 (SIL 2)
maintenance, cut off the
Servo Drive
Servo