fail safe mode in level transmitter works

How fail safe mode in level transmitter works? customer requesting for fail safe mode when the transmitter got any issue or power loss on the transmitter

Here's what Siemens says for one of their radar level transmitters:





The an offscale low or offscale high level is likely to trip alarms, which is one means of knowing that measurement is invalid. Whether high of low depends on what happens, whether pumps turn or off.



Holding at the last value might not alert anyone to the failure condition.

danw said:

Here's what Siemens says for one of their radar level transmitters:

The an offscale low or offscale high level is likely to trip alarms, which is one means of knowing that measurement is invalid. Whether high of low depends on what happens, whether pumps turn or off.



Holding at the last value might not alert anyone to the failure condition.

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so how to differentiate the outputs , i mean if the high level triggers also get the same output and the fail safe also will get the same , how to differentiate these two output?iam using the FTL62 level switch from E&H,Kindly reply ,i dont have any idea about this fail safe attached the link with this https://bdih-prod-assetcentralapi-a...500261EDB89B75B40D436B0BA/TI01539FEN_0220.pdf

"Fail" states are normally configured above and/or below Hi and Lo states. It makes little sense to make them equivalent.

If the signal is within the normal 4-20mA range, then high and low level alarms are valid.

If it's less than 3.8mA or greater than 20.5mA then signal a sensor fault.

I use the sensor fault bit to mask the level alarms, so the operator only gets a "sensor fault" and not an additional level alarm.

To do that your delay on the level alarm needs to be longer than the delay on the sensor fault alarm.

Typically if I'm seeing a faulty sensor then all equipment that operates from that sensor either needs to to stop, or switch to some form of alternative or backup control method