In this article, we will be discussing calibration of capacitance type level transmitter.
Capacitance type level transmitter used for both conductive and non-conductive liquid. Due to harsh processes and years of operating hour cause the transmitter to drift. So, it is important to do calibration in the defined interval as per manufacture norm.
Let consider if the transmitter is Analog type :
1. First, keep the level of the tank at 0%, connect the multimeter in series to know corresponding mA reading. If it won't show 4mA then adjust zero pot.
2. Now fill the tank till 100%, check mA reading. If it won't show 20 mA then adjust span pot.
3. Repeat the above step for better accuracy.
If the transmitter is SMART type :
1. Connect HART in parallel with transmitter and multimeter in series. Fill the corresponding liquid and note down level @0%, 25%, 50%, 75% and 100% in both ascending and descending.
2. Check the error and adjust zero and span pot. If the error still exists then, go to below step.
3. For LRV keep level at 0%, if the reading is 4mA and input is not at zero levels then in HART do the input or sensor trim and take the reading again.
4. For URV fill liquid till 100%, if the output is not 20 mA then from the HART do output trim.