Goodrive600 series high-performance multifunction VFD
STO function description
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Appendix F STO function description
Reference standards: IEC 61508-1, IEC 61508-2, IEC 61508-3, IEC 61508-4, IEC 62061, ISO 13849-1, and IEC
61800-5-2
You can enable the safe torque off (STO) function to prevent unexpected startups when the main power supply of the
drive is not switched off. The STO function switches off the drive output by turning off the drive signals to prevent
unexpected startups of the motor (see the following figure). After the STO function is enabled, you can perform
some-time operations (such as non-electrical cleaning in the lathe industry) and maintain the non-electrical components
of the device without switching off the drive.
Control
circuit
+24V
Switch, relay, and so on
UDC+
UDC-
Drive
circuit
PWM+
PWM-
U/V/W
H1
H2
Note:
The contacts of the safety switch must be opened
o r c l o s e d w i t h i n 2 5 0 m s ; a n d t h e c a b l e t h a t
connects the VFD to the safety switch cannot be
longer than 25 m.
COM
F.1 STO function logic table
The following table describes the input states and corresponding faults of the STO function.
STO input state
Corresponding fault
H1 and H2 opened simultaneously
The STO function is triggered, and the drive stops
running.
Fault code:
40: Safe torque off (STO)
H1 and H2 closed simultaneously
The STOP function is not triggered, and the drive runs
properly.
One of H and H2 opened, and the other
closed
The STL1, STL2, or STL3 fault occurs.
Fault code:
41: Channel H1 exception (STL1)
42: Channel H2 exception (STL2)
43: Channel H1 and H2 exceptions (STL3)
F.2 STO channel delay description
The following table describes the trigger and indication delay of the STO channels.
STO mode
STO trigger and indication delay
1, 2
STO fault: STL1
Trigger delay < 10 ms
