Parker AC890PX Series, Product Manual

Page: 86 / 517

Safe Torque Off
4-20
AC890PX AC Drive
*** TRIPPED ***
SAFE TORQUE OFF
STO Trip Annunciation
The MMI will display a STO trip message when STO becomes active, i.e. STO prevents the drive from
running, thus:
6901 Operator Display 6511 Operator Display
The above shows the two types of STO alarm text for when the (same) STO function has been activated.
This message is displayed immediately if on starting the drive or whilst the drive is running:

One or both STO user inputs X11/01 or X11/03 is or goes low, or

The 890 drive has detected a fault in the STO circuit.
Note that an out-of-box 890 drive will report this trip if the drive, as supplied, has no connections to X11
when it is first started. Appropriate connections must be made to X11 to prevent this trip from occurring, as
described elsewhere in this chapter. The user must decide if STO is to be permanently inactive, or to make
use of the STO feature. If you do not require to use the STO feature see the “
Applications that do not require
STO function
” section on page 4-25.
Safe Torque Off is inserted into the trips history buffer (see Chapter 11) if STO is active when the drive is
attempted to be started or if it becomes active while the drive is running, indicating an abnormal condition.
The trips history buffer is not updated if STO becomes active while the drive is not running.
Note: The normal method of operation is for STO to become active while the drive is not running and the
motor is intended not to rotate. Use on rotating motors or moving loads requires appropriate, application
specific risk assessment.