LAUMAS Elettronica Weight Indicator W200BOX

Load cell resistance measurement (use a digital multimeter):

- Disconnect the load cells from the instrument and check that there is no moisture in the cell junction box caused by condensation or water infiltration. If so, drain the system or replace it if necessary.

- The value between the positive signal wire and the negative signal wire must be equal or similar to the one indicated in the load cell data sheet (output resistance).

- The value between the positive excitation wire and the negative excitation wire must be equal or similar to the one indicated in the load cell data sheet (input resistance).

- The insulation value between the shield and any other cell wire and between any other cell wire and the body of the load cell must be higher than 20 Mohm.

Load cell voltage measurement (use a digital multimeter):

- Take out the load cell to be tested from underneath the container, or alternatively, lift the container support.

- Make sure that the excitation of two wires of the load cell connected to the instrument (or amplifier) is 5 VDC ±3%.

- Measure the response signal between the positive and the negative signal wires by directly connecting them to the tester, and make sure that it is comprised between 0 and 0.5 mV.

Check that the display shows the weight and that when loading the load cells there is an increase in weight. If there is not check and verify the connections and correct positioning of the load cells.

- If the instrument has already been theoretical CALIBRATED (plant system identification tag present on the instrument and on the cover: load cell’s rated data already entered):

▫ Reset to zero (see section TARE WEIGHT ZERO SETTING)

▫ Check the calibration with sample weights and correct the indicated weight if necessary (see section REAL CALIBRATION (WITH SAMPLE WEIGHTS)).

- If the instrument HAS NOT BEEN CALIBRATED (missing plant system identification tag) proceed with calibration:

▫ If load cells data are unknown, follow the procedure in section REAL CALIBRATION (WITH SAMPLE WEIGHTS)

▫ Enter the rated data of load cells following the procedure given in section THEORETICAL CALIBRATION

▫ Reset to zero (see section TARE WEIGHT ZERO SETTING)

▫ Check the calibration with sample weights and correct the indicated weight if necessary (see section REAL CALIBRATION (WITH SAMPLE WEIGHTS)).