Operation And Maintenance; Functional Tests; Functional Test Using The Sto Feedback Signal; Functional Test Without Using The Sto Feedback Signal - Danfoss iC7 Series Operating Manual

iC7 Series Functional Safety
Operating Guide

6 Operation and Maintenance

6.1 Functional Tests

• It is required for PL e or SIL3 to conduct a functional test every 3 months to detect any failure or malfunction of the STO func-
tionality.
• It is required for PL d or SIL2 to conduct a functional test every 12 months to detect any failure or malfunction of the STO func-
tionality.
• It is recommended, but not required for PL c or SIL1 to conduct a functional test every 12 months to detect any failure or mal-
function of the STO functionality.
If the functional test fails, safe operation cannot be guaranteed.
1. Conduct the functional test by performing the steps described in
6.1.2 Functional Test Without Using the STO Feedback

6.1.1 Functional Test Using the STO Feedback Signal

The feedback signal (that is, Reference) is active whenever the STO function is activated internally by both redundant STO channels
(A+B). It is an easy indicator that both channels are working.
Table 8: Functional Test Using the STO Feedback Signal
Test procedure
1 Power on the frequency converter.
2 Check that no safety faults are present.
3 Start the motor.
4 Verify that the STO Feedback output does not signal an active STO.
5 Activate the STO function by removing the 24 V DC voltage supply to STO input channel A and B simultane-
ously while the frequency converter drives the motor (that is, the mains supply is not interrupted).
6 Verify that the motor coasts.
It may take a long time for the motor to stop.
7 Verify that the STO Feedback output signals an active STO. The output signals a full STO only when both chan-
nels are invoked.
8 Give a start command to verify that the STO function blocks the drive's operation. The motor must not start.
9 Reapply 24 V DC to STO inputs.
10 Optional step, only with the manual reset mode setting:
Send a reset signal via fieldbus, digital I/O, or control panel.
11 Ensure that the motor becomes operational and runs within the original speed range.

6.1.2 Functional Test Without Using the STO Feedback Signal

As an alternative solution, it is also possible to verify the STO function without the feedback signal. In this case, both channels have
to be tested separately.
Table 9: Functional Test Without Using the STO Feedback Signal
Test procedure
1 Power on the frequency converter.
2 Check that no safety faults are present.
Danfoss A/S © 2023.03
N O T I C E
6.1.1 Functional Test Using the STO Feedback Signal
Signal.
Operation and Maintenance
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AQ319741840653en-000201 / 136R0268 | 17
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