Siemens sitrans PROBE LU - Output Scaling and Limits; Process Value and Output Scaling; Output Limits (Alarms and Warnings)

Page 92 SITRANS Probe LU (HART) – OPERATING INSTRUCTIONS A5E32337695
F: Technical References
If an invalid measurement is generated by the application (for example, material level
outside threshold settings), the Failsafe timer (P070) will control the speed of the Failsafe
response. When the Failsafe timer expires, the device outputs the value selected in P071.
If a valid measurement is received before the timer expires, the timer will be reset.
If Failsafe mode is activated by a fault (see General Fault Code on page 82), the
instrument will go into Failsafe mode without delay.
Chemical compatibility
The plastic materials used in the construction of SITRANS Probe LU (ETFE, PBT, and
PVDF) are resistant to attack from most chemicals. For exposure to specific
environments, check with chemical compatibility charts before installing and operating
SITRANS Probe LU in your application.
Startup Behavior
Notes:
• SITRANS Probe LU (HART) is designed to start reliably with a power supply
capable of delivering at least 25 mA.
• When connected to a power supply with a current limit of < 25 mA, the Probe LU
may not start reliably.
0
5
10
15
20
25
30
35
0246810121416
with current limited power supply without current limited power supply
Typical Startup Current
Time (seconds)
Current (mA)
Loop Power Supply
without Current Limit
Loop Power Supply with
25 mA Current Limit
Current-limited power
No current limit