ABB ACQ580-04 Guía De Instalación Rápida página 9

Safe torque off (STO)
The drive has a Safe torque off function (STO) in accordance with IEC/EN 61800-5-2. It can be used, for
example, as the final actuator device of safety circuits that stop the drive in case of danger (such as an
emergency stop circuit).
When activated, the STO function disables the control voltage of the power semiconductors of the drive output
stage, thus preventing the drive from generating the torque required to rotate the motor. The control program
generates an indication as defined by parameter 31.22. If the motor is running when STO is activated, it coasts
to a stop. Closing the activation switch deactivates the STO. Any faults generated must be reset before
restarting.
The STO function has a redundant architecture, that is, both channels must be used in the safety function
implementation. The safety data given in this manual is calculated for redundant use, and does not apply if
both channels are not used.
WARNING! The STO function does not disconnect the voltage from the main and auxiliary circuits of the drive.
Notes:
• If stopping by coasting is not acceptable, stop the drive and machinery using the appropriate stop mode
before activating the STO.
• The STO function overrides all other functions of the drive.
Wiring

The safety contacts must open/close within 200 ms of each other. ABB recommends that you use the double-
shielded twisted-pair cable for the connection. The maximum length of the cabling between the switch and the
drive control unit is 300 m (1000 ft). Ground the shield of the cable at the control unit only.
Validation

To ensure the safe operation of a safety function, a validation test is required. The test must be carried out by a
competent person with adequate expertise and knowledge of the safety function. The test procedures and
report must be documented and signed by this person. Validation instructions of the STO function can be
found in the drive hardware manual.
Technical data

Minimum voltage at IN1 and IN2 to be interpreted as "1"¨ 13 V DC
STO reaction time (shortest detectable break)
STO response time
Fault detection time
Fault reaction time
STO fault indication (parameter 31.22) delay
STO warning indication (parameter 31.22) delay
Safety integrity level (EN 62061)
Performance level (EN ISO 13849-1)
The drive STO is a type A safety component as defined in IEC 61508-2. For the full safety data, exact failure
rates and failure modes of the STO function, refer to the drive hardware manual.
EN – Quick installation guide 9
1 ms
2 ms (typical), 30 ms (maximum)
Channels in different states for longer than 200 ms
Fault detection time + 10ms
< 500 ms
< 1000 ms
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