Safe Stop 1 (Ss1) Principle - Vacon OPTAF User Manual

STO AND SS1 SAFETY FUNCTIONS
3.2

Safe Stop 1 (SS1) principle

The Safe Stop 1 (SS1) safety function initiates the motor deceleration and initiates the STO after a
(user set) time delay.
Frequency
f
actual
0
Figure 5. 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 6.
Safe Stop 1 (SS1)
Time Delayed Safety Relay
Subsystem
Local contacts: https://www.danfoss.com/en/contact-us/contacts-list/
Stop
Motor
deceleration
Time delay
Safety Relay
Figure 6. Safe Stop 1 (SS1) safety function
Safe Torque Off (STO)
Vacon NX Safe Torque Off (STO)
Subsystem
+
vacon • 17
Time
11054.emf
STO
11055.emf