416 The Safe torque off function
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Activation switch
In the wiring diagrams, the activation switch has the designation [K]. This
represents a component such as a manually operated switch, an emergency stop
push button switch, or the contacts of a safety relay or safety PLC.
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In case a manually operated activation switch is used, the switch must be of
a type that can be locked out to the open position.
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The contacts of the switch or relay must open/close within 200 ms of each
other.
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A CPTC thermistor protection module or an FSPS safety functions module can
also be used. For more information, see the module documentation.
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Cable types and lengths
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ABB recommends double-shielded twisted-pair cable.
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Maximum cable lengths:
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300 m (1000 ft) between activation switch [K] and drive control unit
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60 m (200 ft) between multiple drives
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60 m (200 ft) between external power supply and first control unit
Note: A short-circuit in the wiring between the switch and an STO terminal causes
a dangerous fault. Therefore, it is recommended to use a safety relay (including
wiring diagnostics) or a wiring method (shield grounding, channel separation)
which reduces or eliminates the risk caused by the short-circuit.
Note: The voltage at the STO input terminals of the drive must be at least 13 V DC
to be interpreted as "1".
The pulse tolerance of the input channels is 1 ms.
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Grounding of protective shields
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Ground the shield in the cabling between the activation switch and the control
unit at the control unit only.
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Ground the shield in the cabling between two control units at one control unit
only.