DOC-0017-03-EN: AC15 Series - Hardware Installation Manual 
  DOC-0017-03-EN-B   04.04.2023   59 (125) 
Expected Reaction & Effect 
6 
With the inverter running and the motor 
turning at SPT1, momentarily disconnect 
terminal STOA (maximum duration of 
disconnect = 1 second), while retaining 
+24V 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 
24V. Try to restart the drive. 
Inverter must restart at SPT1. 
8 
With the inverter running and the motor 
turning at SPT1, momentarily disconnect 
terminal STOB (maximum duration of 
disconnect = 1 second), while retaining 
+24V 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 
24V. Try to restart the drive. 
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 24V to terminal STOA, and then 
try to restart inverter. 
STO trip must not clear. 
Inverter must not start. 
Remove and re-apply all power to the drive 
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 24V to terminal STOB, and then 
try to restart inverter. 
STO trip must not clear. 
Inverter must not start. 
Remove and re-apply all power to the drive 
Try to restart inverter at SPT1. 
Inverter must start at SPT1. 
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.