Chemical Compatibility; Startup Behavior - Siemens SITRANS Probe LU Operating Instructions Manual

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
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.
Typical Startup Current
35
30
25
20
15
10
5
0
0
No current limit
Page 92 SITRANS Probe LU (HART) – OPERATING INSTRUCTIONS
Loop Power Supply
without Current Limit
Loop Power Supply with
25 mA Current Limit
2 4 6
Time (seconds)
with current limited power supply
General Fault Code
on page 82), the
8 10
Current-limited power
without current limited power supply
12 14 16
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