Sto Properties - Danfoss iC7 Series Operating Manual

Operating Guide | iC7-Automation Functional Safety Functional Safety for Frequency Converters with STO, Not Upgradable (+BEF1)
Terminating STO and resuming normal operation
1.
Reapply 24 V DC supply to safe inputs.
2.
Give a reset signal via fieldbus, digital I/O, or the control panel.
Set the STO function to automatic restart by setting the value of parameter 7.3.1 Safe Torque Off Responsefrom the default
value Fault (manual reset) to value Warning (automatic reset). Automatic reset means that STO is terminated and normal
operation is resumed, when the 24 V DC is applied to STO inputs. No reset signal is required.
3.1.6

STO Properties

For flexible adaptation to the safety system, the STO inputs contain the following properties:
Galvanic isolation of terminals: The functional safety I/O terminal blocks on the control board (X31, X32) have separate, galvanically
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isolated inputs to allow, for example, interchanging of the polarities of the STO input terminals as shown in
Test pulse filtering: Several control modules test their safe outputs using Test Pulse Pattern (on/off tests), to identify faults due
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to either short- or cross-circuiting. When connecting the STO inputs with a safe output of a control module, test pulses shall not
activate STO. For that reason, test pulses for no longer than 2 ms is ignored on the STO input lines.
2 ms max.
STO Ch. A/B
STO function
Active
Inactive
Figure 1: Test Pulse Filtering
Asynchronous input tolerance: The input signals at the STO terminals are not always synchronous. If the discrepancy between the
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2 signals is longer than 500 ms, the drive indicates an STO fault as described in
the STO function.
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Test pulse STO demanded
Time
Debounce time
Time
Table 4. This feature does not delay the activation of
AQ319741840653en-000401 / 136R0268
Figure 1 and Figure 2.