Safe Stop And Preventing A Restart - Eaton Rapid Link 5 Manual

2.8.2 Safe stop and preventing a restart

CAUTION

When used in conjunction with permanent magnet motors and
in the unlikely case of multiple output semiconductors (IGBTs)
failing, having the STO function activated may result in a motor
shaft rotational movement of 180 degrees/p (p = Number of
motor pole pairs).
DANGER

The STO function is an electronic mechanism that does not
provide sufficient protection against electric shock. Additional
potential isolation measures may be accordingly required
(e.g., switch-disconnector).
DANGER

Only the STO function of the drive can be used as a safety
function of a machine.
None of the other functions of the drive can be used to execute
a safety function.
WARNING

The STO control inputs act statically and in a similar way to a
contactor:
As long as the STO inputs are voltage-free, the torque-genera-
ting energy is no longer supplied and thus the drive is also relia-
bly prevented from starting up. If the STO inputs are supplied
with power again, the drive can also start up automatically if all
other requirements are met. This is the case, for example, when
the voltage supply returns.
The purpose of the STO function is to prevent the drive from making the
motor produce a torque when there is no input signal at pin 3 and pin 4.
This makes it possible to integrate the drive into a complete safety system in
which the Safe Stop function needs to be fully implemented.
DANGER

The STO function cannot prevent an unexpected restart or an
automatic restart if the STO inputs receive a signal. Accordingly,
it must not be used to perform maintenance or cleaning work on
the machine.
Rapid Link 5 · RAMO5 · RASP5 05/20 MN034004EN www.eaton.com
2 Engineering
2.8 Safe Torque Off (STO)
51