Siemens SITRANS LVL200E Operating Instructions Manual page 27

MAN-100411
This function test can be carried out with measurement setups in
conjunction with the two-wire electronics module.
The recurring proof test according to IEC 61508 can be carried out
through a short interruption (> 2 seconds) of the supply line to the
sensor.
By doing so, a test procedure is started. The correctness of the sub-
sequent switching conditions on the indications of the SPLC must be
monitored.
a. Short interruption of the supply line to the sensor
You can carry out the function test with the outputted current values
also directly via a safety PLC or a process control system.
1. Separate the instrument briefly (> 2 s) from voltage supply.
Check if all three switching conditions change in the correct
sequence and the specified duration. By doing so, you can check
the function of the measuring system.
You can find the test procedure under "Implementation - Function
test".
Make sure the connected downstream devices are activated dur-
ing the function test.
2. Push the mode switch (min./max.) on the signal conditioning
instrument.
Check if the switching status changes (signal lamp - switching
status). By doing so, you can check the function of the measuring
system.
If this is not the case, then there is a fault in the measuring sys-
tem.
Make sure the connected downstream devices are activated dur-
ing the function test.
Implementation - Function test
When the SITRANS LVL200E is connected to a processing system or
an SPLC, you have to interrupt the connection cable to the sensor for
> 2 seconds. The switching delay must be set to 0.5 s.
After releasing the test key or interrupting the connection cable to the
sensor, the complete measuring system can be checked on correct
function. The following operating conditions are simulated during the
test:
•
Fault message
•
Empty signal
•
Full signal
SITRANS LVL200E - Operating Instructions
27