MSG11-5715-743/EN: AC20F Series - Hardware Installation Manual
78 (148)
MSG11-5715-743/EN 24.04.2023
STO Test
Step
Test Check or Activity
Expected Reaction & Effect
STO Channel A Check
6
With the inverter running and the motor
turning at SPT1, momentarily disconnect
terminal STOA (maximum duration of
disconnect = 1 second), while retaining
+24 V at terminal STOB.
Motor must immediately coast to a rest.
Inverter must report a STO trip immediately.
7
Ensure terminals STOA and STOB are both
24 V. Try to restart the drive.
STO trip must clear.
Inverter must restart at SPT1.
STO Channel B Check
8
With the inverter running and the motor
turning at SPT1, momentarily disconnect
terminal STOB (maximum duration of
disconnect = 1 second), while retaining
+24 V at terminal STOA.
Motor must immediately coast to a rest.
Inverter must report a STO trip immediately.
9
Ensure terminals STOA and STOB are both
24 V. Try to restart the drive.
STO trip must clear.
Inverter must restart at SPT1.
STO Channel A Fault Check
10
Ensure the inverter is running and that the
motor is turning at SPT1.
Disconnect terminal STOA for
approximately 5 seconds (must exceed 3
seconds).
Motor must immediately coast to a rest.
Inverter must report a STO trip immediately.
11
The STO function has latched in hardware
to disable the drive.
Re-apply 24 V to terminal STOA, and then
try to restart inverter.
STO trip must not clear.
Inverter must not start.
12
Remove and re-apply all power to the drive
None.
13
Try to restart inverter at SPT1.
Inverter must start at SPT1.
STO Channel B Fault Check
14
Ensure the inverter is running and that the
motor is turning at SPT1.
Disconnect terminal STOB for
approximately 5 seconds (must exceed 3
seconds).
Motor must immediately coast to a rest.
Inverter must report a STO trip immediately.
15
The STO function has latched in hardware
to disable the drive.
Re-apply 24 V to terminal STOB, and then
try to restart inverter.
STO trip must not clear.
Inverter must not start.
16
Remove and re-apply all power to the drive
None.
17
Try to restart inverter at SPT1.
Inverter must start at SPT1.
18
Stop the inverter.
Inverter must decelerate to rest.
Once the relevant safety test steps have been successfully completed, action must be taken to document
the result. An example protocol specimen is provided below.
Please note that additional or alternative tests may be required depending on the Machine design.
