Danfoss VLT AutomationDrive Design Manual page 55

Introduction to FC 300
FC
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Illustration 3.17 Installation to Achieve a Stopping Category 0
(EN 60204-1) with Safety Cat. 3 (EN 954-1) / PL "d" (ISO 13849-1)
or SIL 2 (EN 62061).
1 Safety relay (cat. 3, PL d or SIL2
2 Emergency stop button
3 Reset button
4 Short-circuit protected cable (if not inside installation IP54
cabinet)
Safe Stop Commissioning Test
After installation and before first operation, perform a
commissioning test of the installation making use of safe
stop. Moreover, perform the test after each modification of
the installation.
Example with STO
A safety relay evaluates the E-Stop button signals and
triggers an STO function on the frequency converter in the
event of an activation of the E-Stop button (See
Illustration 3.18). This safety function corresponds to a
category 0 stop (uncontrolled stop) in accordance with IEC
60204-1. If the function is triggered during operation, the
motor will run down in an uncontrolled manner. The
power to the motor is safely removed, so that no further
movement is possible. It is not necessary to monitor plant
at a standstill. If an external force effect is to be
anticipated, additional measures should be provided to
safely prevent any potential movement (e.g. mechanical
brakes).
NOTE
For all applications with Safe Stop it is important that short
circuit in the wiring to T37 can be excluded. This can be
done as described in EN ISO 13849-2 D4 by the use of
protected wiring, (shielded or segregated).
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FC 300 Design Guide
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37
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MG.33.BD.02 - VLT
Example with SS1
SS1 correspond to a controlled stop, stop category 1
according to IEC 60204-1 (see Illustration 3.19). When
activating the safety function a normal controlled stop will
3
be performed. This can be activated through terminal 27.
After the safe delay time has expired on the external safety
module, the STO will be triggered and terminal 37 will be
set low. Ramp down will be performed as configured in
1
the drive. If drive is not stopped after the safe delay time
the activation of STO will coast the frequency converter.
NOTE
When using the SS1 function, the brake ramp of the drive
is not monitored with respect to safety.
Example with Category 4/PL e application
Where the safety control system design requires two
channels for the STO function to achieve Category 4 / PL e,
one channel can be implemented by Safe Stop T37 (STO)
and the other by a contactor, which may be connected in
either the drive input or output power circuits and
controlled by the Safety relay (see Illustration 3.20). The
contactor must be monitored through an auxiliary guided
contact, and connected to the reset input of the Safety
Relay.
Paralleling of Safe Stop input the one Safety Relay
Safe Stop inputs T37 (STO) may be connected directly
together if it is required to control multiple drives from the
same control line via one Safety Relay (see Illustration 3.21).
Connecting inputs together increases the probability of a
fault in the unsafe direction, since a fault in one drive
might result in all drives becoming enabled. The
probability of a fault for T37 is so low, that the resulting
probability still meets the requirements for SIL2.
Illustration 3.18 STO example
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FC
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