Frequency Converters With Functional Safety Group 1 (Not Upgradable); Sto Properties - Danfoss iC7 Series Operating Manual

iC7 Series Functional Safety
Operating Guide
Configurable security features can be adjusted according to application requirements. Depending on the software version of the
frequency converter, the parameters can be password-protected.

3.5 Frequency Converters with Functional Safety Group 1 (Not Upgradable)

Frequency converters with STO (+BEF1) provide the Safe Torque Off (STO) safety function with a dual-channel, galvanically isolated
input, and an STO feedback signal for diagnostic purposes.
The drive integrates the STO functionality via the functional safety I/O terminals as described in
The iC7 drive with STO functionality is designed and approved suitable for the requirements of:
• Category 3 in EN ISO 13849-1.
• Performance Level "e" in EN ISO 13849-1.
• SIL 3 in IEC 61508 and EN 61800-5-2.
The STO safety function is active if one or both of the STO inputs are not connected to a +24 V signal. The frequency converter is not
able to go to the RUN state. For more information, see
Prerequisites for normal operation (STO function is not active) are:
• STO A and STO B signals are energized.
• No internal faults are active.
All control input and outputs are galvanically isolated from supply voltage (PELV) and other high voltage terminals, unless other-
wise specified.
Table 3: Functional Safety I/O Terminals in Frequency Converters
Terminal X31
Numbering Terminal Name
41 24 V
42 S.INA+
43 S.INB+
44 S.FB+
Table 4: Instances of the STO Function and STO Feedback Output
STO inputs
Both inputs energized with
24V DC
Power removed from both in-
puts
Only one input energized
Regular STO demand: Can be either fault or warning depending on restart settings.
1
Failure in demand or due to internal fault (always a "fault", not configurable). Indicated after discrepancy timer (500 ms) elapsed.
2

3.5.1 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, galvani-
cally isolated inputs to allow, for example, interchanging of the polarities of the STO input terminals as shown in
and Illustration 8.
• Test pulse filtering: Several control modules test their safe outputs using Test Pulse Pattern (on/off tests), to identify faults due
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 will be ignored on the STO input lines.
Danfoss A/S © 2023.03
Table 4.
Functions
+ 24 V DC Output
+ STO Input Channel A
+ STO Input Channel B
+ STO Input Channel B
Operating conditions
Normal operation
STO demand
Failure in demand or due
to internal fault
Terminal X32
Numbering Terminal Name
45 GND
46 S.INA–
47 S.INB–
48 S.FB–
STO function STO feedback signal
Deactivated Deactivated
Activated Activated
Activated Deactivated
iC7 Functional Safety
Table 3.
Functions
0 V/GND
- STO Input Channel A
- STO Input Channel B
- STO Feedback
Fault or warning text
No faults or warnings
"STO activated"
(1)
"STO – Fault [channel
name]"
(2)
Illustration 7
AQ319741840653en-000201 / 136R0268 | 9