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What should I do if the pressure transmitter has no output? Is the power supply, secondary meter or sensor itself faulty?
Nov 01, 2018

When there is no output from the on-site pressure transmitter, we first need to judge what went wrong, but we are rashly thinking that the pressure transmitter has failed, because in many applications, in addition to being used alone, it is possible to Other equipment or systems are used in combination, such as orifice plates, such as digital meters, such as flow meters. Let's take a look at each of the following

1. If the pressure transmitter is used together with the digital display meter, if the digital display meter is not displayed at this time, the user may say that the pressure transmitter has no output (the user who often encounters the call says this), in fact, this problem Obviously, it is unreasonable to rashly determine that the pressure transmitter has no output. If the pressure transmitter is output normally, it is also possible that the digital display has failed. This is the user's misunderstanding of the on-site fault. So how do you tell if the pressure transmitter is output normally? Very simple, use a multimeter to directly measure the output of the pressure transmitter, and measure whether to use 4-20mA current value. Of course, this happens when used in conjunction with other instruments, as well as measuring the current with a multimeter.

2, we know that the transmitter needs 24V power supply, if the pressure transmitter has no output, we must first consider whether there is 24V power supply or 24 power supply is normal, of course, this is the most basic electrician common sense. However, if the site is as described in the first point, in series with a digital display or other meter with a 24V power supply, the pressure transmitter does not need to provide 24V power again. This second aspect is when using a pressure transmitter alone.

3. If the 24V power supply is available and the power supply is normal, there is no output from the pressure transmitter at this time. It is necessary to check whether the power cable is connected reversely, and whether the positive and negative poles are connected incorrectly.

4. If the wiring is correct, then it is necessary to check whether there is a line break in the entire circuit; or check whether the meter is selected incorrectly (the input impedance should be ≤250Ω).

5. If the above checks are normal, it is possible that the hardware of the pressure transmitter has failed. For example, when the on-site pressure transmitter started to have a problem with the 24V power supply, the circuit board of the pressure transmitter burned out. Of course, there is no display and no output directly; for example, the overload and withstand voltage capability of the selected pressure transmitter. Both are inconsistent with the conditions on site, and there may be excessive pressure over the pressure transmitter components, and there will be no output from the pressure transmitter; for example, the pressure transmitter is equipped with a live display, that is, with a meter, if this When the meter head is damaged, there will be no output from the pressure transmitter. If it is judged whether the header is damaged, the two wires of the direct header are short-circuited. If the short-circuit is normal, it indicates that the header is damaged.

The above should include all the common causes of failure. Of course, the factors of failure will change with the changes in the field. The sixth and seventh causes may occur in the future, but they do not hinder the extremely wide application of pressure transmitters, because at least The above five kinds of faults can be said to be the basic common sense range, in which the second, third and fourth causes analysis rarely occurs, and the common ones belong to the first and fifth articles, and they are still easy to solve.