SS1(c) – Safe Stop 1 according to IEC 61800-5-2

SS1(c) (safe stop 1, function variant c according to IEC 61800-5-2) by means of suitable external control (e.g. safety relay with delayed disconnection).

The following sequence is mandatory:

Decelerate the drive using an appropriate brake ramp specified via setpoints.
Disconnect the STO input (= triggering the STO function) after a specified safety-related time delay.

This safety function corresponds to a controlled stop according to EN 60204‑1, stop category 1.

The following figure illustrates the SS1(c) function:

v		Speed
t		Time
t₁		Point of time when brake ramp is initiated
t₂		Point of time when STO is triggered
Δt		Delay time until STO is triggered
		Safe time delay range
		Disconnection range