Safe Stop 1 (Ss1) Principle - Vacon optbj Safety Manual

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5.2

Safe Stop 1 (SS1) Principle

After a safe stop command the motor starts decelerating and SS1 safety function initiates the STO
after a user set time delay.
Frequency
Figure 8. The principle of Safe Stop 1 (EN 61800-5-2, SS1 type c)
The Safe Stop 1 (SS1) safety function consists of two safety related subsystems, an external time
delayed safety relay and the STO safety function. These two subsystems combined compose the
Safe Stop 1 safety function as shown in Figure 9.
Figure 9. Safe Stop 1 (SS1) safety function
5
Stop
f
actual
Time delay
0
Safe Stop 1 (SS1)
Time Delayed Safety Relay
Subsystem
Safety Relay
Motor
deceleration
Safe Torque Off (STO)
Vacon 100 Safe Torque Off (STO)
Subsystem
+
Local contacts: https://www.danfoss.com/en/contact-us/contacts-list/
STO and SS1 safety functions
Time
11578_uk
STO
11579_uk