MSG11-5715-743/EN: AC20F Series - Hardware Installation Manual
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MSG11-5715-743/EN 24.04.2023
STO Test
Step
Test Check or Activity
Expected Reaction & Effect
6
R24 V to terminals STOA and
STOB and acknowledge the STO trip.
STO trip must clear.
7
Try to restart the inverter at SPT1.
Inverter must restart at SPT1.
8
Stop the inverter.
Inverter must decelerate to rest.
This test can also be automated - where the STO channels can be triggered via contacts of an external
relay.
8.7
STO Troubleshooting
The table below is for guidance only and may not be a comprehensive list of all possible symptoms relating
to STO.
Parker will not accept responsibility for any consequences arising from its incompleteness or inaccuracy.
Problem
AC20F
Display
STO Input
Channel A
wrt 0 V
STO Input
Channel B
wrt 0 V
Possible
Cause
Description
Inverter will not
run when given
a start
command
Tripped:
31 Safe
Torque Off
< 15.0 V
< 15.0 V
STO is
invoked.
When safe to do so,
connect STOA and STOB
to a 24 VDC supply.
Tripped:
31 Safe
Torque Off
>15.0 V &
< 25.2 V
*
>15.0 V &
< 25.2 V
*
STO Fault
Latch may
have tripped.
Remove all power from
the inverter before re-
applying.
If symptom persists,
immediately return the
inverter for repair.
Tripped:
(Any other
trip 1-30 or
32-37)
>15.0 V &
< 25.2 V
*
>15.0 V &
< 25.2 V
*
Inverter has
tripped, but
not due to
STO.
Reset the trip and remove
its cause.
If symptom persists, return
the inverter for repair.
Any other
message
>15.0 V &
< 25.2 V
*
>15.0 V &
< 25.2 V
*
Faulty
Hardware.
Return the inverter for
repair.
Inverter starts
unexpectedly
X
< 5.0 V
< 5.0 V
Faulty
Hardware.
Immediately return the
inverter for repair.
X
> 5.0 V
> 5.0 V
STO not
invoked by
the user.
Use STO in accordance
with the instructions
documented in this
chapter.
Inverter fails
Comprehensive
or Regular STO
test
X
X
X
Faulty
Hardware.
Immediately return the
inverter for repair.
*
26.4 V in a maximum operating ambient of 40 °C
