A pressure switch may appear correct during static testing but cause intermittent trips during operation. In these cases, both the actual pressure and the sensing line need to be checked.
Clogged tube
Dirt or condensate can delay pressure transmission to the pressure switch and cause malfunction.
Loose electrical contact
Vibrations can affect terminal blocks or internal contacts. The problem appears as a momentary alarm.
Setpoint too close to normal operating pressure
If the setpoint has a small margin from normal operation, minor fluctuations may cause frequent trips.
Hysteresis
The difference between activation and reset must be taken into account. It is not just a single nominal value that should be evaluated.
Correct diagnosis
The best practice is simultaneous recording of the actual pressure and the digital status of the pressure switch in the PLC or BMS.
