Yes, the high humidity during the rainy season causes condensation in the electrical control cabinet, which continuously interferes with the vacuum sensor on three levels: hardware, signal, and reference. This is explained in detail below:

I. Condensation and electrical leakage at the sensor terminals cause signal drift and erratic fluctuations.

Vacuum transmitters transmit weak current/voltage signals. When condensation forms on the terminals and terminal blocks, it creates a conductive water film:

Minor leakage occurs between signal wires and shielding wires, causing measured values to fluctuate erratically and negative pressure readings to oscillate continuously;

Condensation corrodes the copper terminals, creating an oxide layer that causes contact resistance to fluctuate continuously, resulting in significant deviations in readings under the same negative pressure;

In severe cases, signal short circuits occur, causing the controller to report a vacuum probe failure, lose the signal, and shut down the system.

II. Condensation on the Transmitter Circuit Board, Component Temperature Drift, and Reference Offset

The vacuum sensor contains a built-in circuit board, precision resistors, and compensation chips; condensation adheres to the circuit board:

Moisture alters the insulation properties of components, causing the pressure compensation reference to fail and resulting in a fixed offset that drifts again shortly after calibration;

Minor corrosion of the circuit board causes the temperature compensation circuit to malfunction, further amplifying vacuum errors when temperatures change;

Long-term accumulation of condensation forms water stains and verdigris, ultimately causing chip damage and rendering the probe completely inoperable.

III. Water Ingress into the Venting and Pressure-Transmitting Tubing, Leading to Distorted Transmission of Actual Negative Pressure

If the sensor’s pressure-transmitting tubing runs through the interior of the electrical control cabinet, condensation can flow along the tubing into the transmitter’s diaphragm chamber:

The diaphragm is pressed against by accumulated water, preventing it from accurately sensing the negative pressure inside the chamber; readings remain consistently high or become stuck;

The accumulated water blocks the pressure-transmitting tubing, preventing the transmission of non-condensable gases; minor air leaks and fluctuations in vapor production cannot be detected at all, and there will be no alarm even if the vacuum gets out of control.

IV. High humidity inside the cabinet exacerbates internal temperature differences, creating a vicious cycle of condensation

During the rainy season, there are significant day-night temperature differences—temperatures rise during the day and drop at night. When the electrical cabinet is sealed and poorly ventilated, moisture repeatedly condenses:

The humidity inside the cabinet remains chronically saturated, and the vacuum probe and wiring are continuously exposed to a damp environment, preventing drift issues from resolving on their own;

Moisture corrodes the channels of the PLC’s analog modules, causing a decline in port insulation; as a result, all pressure and temperature signals are simultaneously disrupted, leading to frequent false triggers in the program’s staged concentration logic.

V. Derived Process Interlock Issues

Distorted vacuum readings lead to a series of abnormal evaporation conditions:

The controller incorrectly judges that sufficient negative pressure is present and continues to increase the temperature for evaporation; however, the actual vacuum is low, causing the boiling point to rise and exacerbating foaming and material carryover;

Low-vacuum alarms are frequently triggered erroneously, causing the unit to repeatedly reduce load, start and stop feeding, and experience significant level fluctuations, which accelerate salt buildup and blockage in the heat exchange plates.