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5 Application Examples
5.1 SISTEMA Data
SISTEMA (Safety Integrity Software Tool for the Evaluation of Machine Applications) is a software utility that provides developers
and testers of safety-related machine controls with comprehensive support in the evaluation of safety in the context of ISO 13849-1.
Functional safety data are available from a data library for use with the SISTEMA calculation tool from the ISA (Institute for Occupa-
tional Safety and Health of the German Social Accident Insurance), and data for manual calculation. SISTEMA is available for down-
load at
Service and support/downloads
sections.
5.2 Emergency Stop of Drive with STO - Category 1, PL c, SIL1
FC
1
e3
0b
g7
33
.1
1
37
2
+24 V
Illustration 4: Application Example, Emergency Stop with STO, Category 1, PL c, SIL1
1
Emergency stop button.
2
Short-circuit protected cable.
Safety function
If there is an emergency, the emergency stop device is activated. The STO function of the drive is activated. Following a stop or
emergency stop command, the drive is halted.
Design features
The circuit can be used up to Category 1, PL c (ISO 13849-1) or SIL1 (EN 62061 and IEC 61508).
The STO function is activated via 1 NC positively operated switch contact (according to IEC 60947-1, IEC 60947-5-1, and IEC
60947-5-5).
The PL c, the complete safety functions have to be calculated (MTTFd).
Use the basic safety principles.
Devices used for activation of STO must be suitable for the selected Category, PL, or SIL.
When implementing the emergency stop, pay attention to the following tips:
Any non-safety related standards should be fulfilled for the application and its components.
The application designer is responsible for selecting suitable components.
To fulfill PL c, the MTTFd and DC for the whole safety function have to be calculated.
The B
10d
value of the emergency stop device shall be known. The B
10d
value has to be high enough to fulfill MTTFd correspond-
ing to PL c.
Implementation in SISTEMA using Danfoss VLT library
As an example, use the subsystem "VLT® AutomationDrive FC 302/FCD 302 Safe Torque Off (Terminal 37)". There is no need to edit
all the parameters which are set in the library.
e3
0b
g7
34
.1
1
SB emergency
stop device
SB FC 300 safe stop
(terminal 37)
from Danfoss VLT library
Illustration 5: Safety-related Block Diagram
AQ313340186453en-00101 / 130R0544
16 | Danfoss A/S © 2021.03
Application Examples
Safe Torque Off
Operating Guide