NORD Drivesystems BU0230 - Manual (Page 60)

Functional safety with NORD SK 200E frequency inverters
60 BU 0230 GB-2712
6 Safety categories
6.1 IEC 60204-1:2005
(German version EN 60204-1:2006)
The requirements of a Category 0 and Category 1 stop function can be fulfilled by the "safe pulse block".
The controlled braking for Category 1 is not fail-safe via the standard functions of the frequency inverter. The
switch-over to the stop function of Category 0 is fail-safe.
6.2 IEC 61800-5-2:2007
(German version EN 61800-5-2:2007)
The requirements for the functions "Safe shut-down torque (STO) and "Safe stop 1" (SS1) can be fulfilled with
the shut-down method "safe pulse block.
With the function SS1, there is no safe monitoring of motor speed reduction or motor speed reduction by the
frequency inverter. If a risk analysis has shown that monitoring is necessary, this must be carried out via an
external safe control unit. The solutions for the function SS1 described in the examples correspond to
characteristics as per IEC 61800-5-2:2007, Section 4.2.2.3, Paragraph c) "Triggering of motor speed reduction
and triggering of the STO function after an application-specific time delay". The motor speed reduction is
carried out via the standard functionality of the frequency inverter and is not fail-safe. The switch-over to the
STO function is fail-safe.
6.3 IEC 61508:2010
(German version EN 61508:2010)
For the safety-relevant stop functions STO and SS1 (designation as per IEC 61800-5-2:2007), frequency
inverters with the safe shut-down methods "safe pulse block" and "switch-off of the 24 V supply" fulfil the
requirements for SIL 3.
Shut-down
method “Safe pulse block” “Safe pulse block” "Switch-off of the 24V supply"
Size Size 1 to 3 Size 4 Size 1 to 3 (SK 205E and SK 215E)
SIL 3 3 3
PFH 0 0,0058FIT = 5,8*10
-12
/h 0
PFD 0 5,23*10
-5
0
DC cannot be established
(PFH=0) >99% cannot be established (PFH=0)
SFF 100 % >99% 100 %
T
M
20 years 20 years 5 years
SIL Safety Integrity Level
PFH Probability of a hazardous failure per hour
PFD Probability of a hazardous failure on call-up
DC Diagnostic coverage level
SFF Proportion of safe failures
T
M
Duration of use
The digital inputs do not have SIL capability