Check the accuracy of the pressure transmitter with a multifunction signal generator

Assuming that the range of the thermocouple temperature transmitter is 4-20 mA, if it is 1-5 V, the method is similar.

Step 1: Check the indexing table of the thermoelectric potential corresponding to the thermocouple; List the temperature-thermoelectric potential comparison table, divided into five levels by %.

Step 2: Zero: Reverse the signal input line, make the potentiometer output to verify the corresponding electromotive force at room temperature on site, adjust the potentiometer Z, and make the ammeter read 4mA.

Full: Positive connection of the signal input line, so that the potentiometer output full-scale corresponding to the electromotive force, adjust the potentiometer s, so that the ammeter reads 20mA. (This electromotive force is the value of the full electromotive force minus the corresponding electromotive force at room temperature).

For example: the temperature transmitter calibration of the room temperature of the verification site is 7, the input signal is k, and the range is 0 1000, and the corresponding electromotive force of 7 is known by checking the meter, and 1000 corresponds to the electromotive force. After the positive connection, the output reading of the potentiometer is, adjust the potentiometer S so that the ammeter reads 20mA.

Step 3: Use the signal generator to input the MV value corresponding to % (theoretical value - cold junction value); Measure the output current with a multimeter.

Step 4: Calculate the error between the theoretical value and the measured value, accuracy = maximum error 16*100%.

Steps: 1. Connect the pressure source (be careful not to leak air), power supply and digital multimeter.

2. Determine the zero point. At zero point pressure, make sure your transmitter shows 4mA. If you don't want to adjust the zero button, because zero is the baseline.

3. Fill up the point pressure, the standard output under this pressure is 20ma, calculate the accuracy, accuracy = (your actual measured value -20mA) 16

4. It is recommended to test the pressure value of % again.

I can help if needed.

How to measure the quality of a pressure transmitter.

1: The pressure sensor can convert the air pressure into a continuous voltage (you need to know the conversion relationship).

2: Select the appropriate amplification circuit or voltage divider circuit according to the range of conversion voltage (if the conversion voltage range is much less than the reference voltage of single-chip microcomputer AD sampling, the amplification voltage is required; If it is greater than, generally simple, you can use partial pressure).

3: The single-chip microcomputer has AD sampling function, and the number of sampling bits is determined according to the accuracy you need to calculate (of course, if there is cost pressure, you can use it to improve the accuracy when the number of bits is low, but the amount of sampling data will be sacrificed).

4: Calculated by the program, and LED display. There are many examples of this online.

In addition, the above is just a simple process, and in order to measure accurately, it is necessary to compensate various circuits and programs at all levels (such as adjusting to 0).

Moreover, I think it is best for you to clarify your needs first (how long is the continuous change, which is directly related to the selection of hardware and the preparation of the program), such as range, error, resolution, etc.

Finally, there are many examples of this kind on the Internet, similar to for example, small weighing systems, there are many circuits on this Internet! You can refer to the knowledge of rotten reference!