Fault Analysis of Differential Pressure Transmitter

Failure analysis

1. Investigation method:

Review the fire, smoke, odor, power supply change, lightning strike, moisture, misuse, and mis-maintenance before the fault occurs.

2. Intuitive method:

Observe the external damage of the circuit, the leakage of the pressure guiding tube, the overheating of the circuit, the state of the power supply switch, etc.

3. Detection method:

1) Open circuit detection: separate the suspected fault part from other parts to see if the fault disappears. If it disappears, determine the fault. Otherwise, you can go to the next step. For example, the intelligent differential pressure transmitter cannot be normal Hart remote communication. The power supply can be disconnected from the body, and the transmitter can be powered by the power supply on the site to check whether the cable is superimposed with an electromagnetic signal of about 2 kHz to interfere with the communication.

2) Short-circuit detection: In the case of ensuring safety, the relevant part of the circuit is directly short-circuited. For example, if the output value of the differential transmitter is too small, the pressure-conducting tube can be disconnected, and the differential pressure signal is directly sent from the first pressure-taking valve. Directly lead to the differential pressure transmitter on both sides, observe the transmitter output to determine the plugging and leakage connectivity of the pilot line.

3) Replacement test: Replace the suspected faulty part and judge the fault location. For example, if the transmitter board is suspected to be faulty, you can temporarily replace it to determine the cause.

4) Division detection: divide the measurement loop into several parts, such as: power supply, signal output, signal transmission, signal detection, sub-section inspection, from simple to complex, from the table and inside, narrow the scope, find the fault position