Safety
WARNING
RISK OF ELECTRICAL SHOCK
The STO function does NOT isolate mains voltage to the
frequency converter or auxiliary circuits. Perform work
on electrical parts of the frequency converter or the
motor only after isolating the mains voltage supply and
waiting for the discharge time to elapse, as specified in
the Safety chapter in the relevant operating instructions/
guides. Failure to isolate the mains voltage supply from
the unit and waiting the time specified could result in
death or serious injury.
•
Do not stop the frequency converter by using
the STO function. If a running frequency
converter is stopped by using the function, the
unit trips and stops by coasting. If this
limitation is not acceptable, for example
because it causes danger, use the appropriate
stopping mode to stop the frequency converter
and machinery before using the STO function.
Depending on the application, a mechanical
brake may be required.
•
STO is suitable for performing mechanical work
on the frequency converter system or affected
area of a machine only. It does not provide
electrical safety. STO must not be used as a
control for starting and/or stopping the
frequency converter.
CAUTION
AUTOMATIC RESTART
Automatic restart behavior is only allowed in 1 of the 2
situations:
•
The unintended restart prevention is
implemented by other parts of the STO instal-
lation.
•
A presence in the dangerous zone can be
physically excluded when STO is not activated.
In particular, paragraph 6.3.3.2.5 of ISO 12100:
2010 must be observed.
MG37D502
Operating Guide
WARNING
RISK OF DEATH AND SERIOUS INJURY
The STO function can be used for asynchronous,
synchronous, and permanent magnet motors. 2 faults
can occur in the power semiconductor of the frequency
converter. When using synchronous or permanent
magnet motors, a residual rotation can result from the
faults. The rotation can be calculated to angle = 360/
(number of poles). The application using synchronous or
permanent magnet motors must take this residual
rotation into consideration and ensure that it does not
pose a safety risk. This situation is not relevant for
asynchronous motors.
NOTICE
Perform a risk assessment for each stop function to
determine the selection of a stop category in accordance
with EN 60204-1:
•
•
•
NOTICE
When designing the machine application, timing and
distance must be considered for a coast to stop (Stop
Category 0 or STO). For more information regarding stop
categories, refer to EN 60204-1.
Danfoss A/S © 01/2018 All rights reserved.
Stop Category 0 is achieved with immediate
removal of power to the actuator, resulting in
an uncontrolled coast to stop. STO according to
EN 61800-5-2 accomplishes a Stop Category 0
stop.
Stop Category 1 is achieved with power
available to the machine actuators to achieve
the stop. Power is removed from the actuators
when the stop is achieved according to EN
61800-5-2 Safe Stop 1 (SS1).
Stop Category 2 is a controlled stop with power
available to the machine actuators. A holding
position under power follows the stop.
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