JUMO 14597 safetyM STB/STW Ex - Safety Temperature Limiter and Safety Temperature Monitor Operating Manual - Manual (Page 40)

6 Safety Manual
2013-04-01 34
Important information:
Variants 1 to 4 were evaluated with JUMO probes according to data sheets 901006 and 902006. For variant 5 no sensor sys-
tem was included (only the JUMO safety
M STB/STW Ex). In this case, the plant operator selects the sensor system. For this
reason, the plant operator is responsible for evaluating the achievable SIL.
If the used SIL-capable sensor consists of hardware and software (e.g. transmitter), the maximum SIL that can be achieved –
irrespective of the architecture – is the one according to which the sensor software was developed (so, for example, if the sen-
sor software has SIL2, the max. achievable SIL is 2).
The possibility of connecting passive sensors such as dual thermocouples or Pt100/1000 sensors means that the sensors do
not necessarily require an SIL qualification. In this case, the specification of the failure rates for the passive sensors is sufficient
Table 1: Achievable SIL
Variant Connected sensors Sensor system
architecture Logic ar-
chitecture Achievable SIL
1 1x Pt100 2-wire circuit 1oo1 1oo2D SIL2
1a 2x Pt100/1000 2-wire circuit 1oo2 1oo2D SIL3
2 2x Pt100/1000 3-wire circuit 1oo2 1oo2D SIL3
3 2x thermocouple 1oo2 1oo2D SIL3
4 1x Pt100/1000 2-wire + 3-
wire circuit
1x thermocouple 1oo2 1oo2D SIL3
5 STB/STW 701155 without
sensor system 1oo2D archi-
tecture
No probe or use of 4 to
20 mA
This means the sensor is not
taken into account in the cal-
culation. Sensors con-
nected by the
plant operator;
architecture
acc. to connec-
tion 1oo1 or
1oo2 1oo2D SIL of the used
sensor (HW only) Max. achievable SIL of the
system with 1oo1 sensor
system architecture Max. achievable SIL of the
system with 1oo2 sensor
system architecture
SIL1 SIL1 SIL2
SIL2 SIL2 SIL3
SIL3 SIL3 SIL3