Treatment of temperature drift in vacuum pressure switches

When the temperature of a vacuum pressure switch changes, the measured value may deviate from the true value, that is, temperature drift, which will seriously affect its measurement accuracy and reliability. The following introduces the methods for handling temperature drift from aspects such as temperature compensation, hardware improvement, installation optimization, regular calibration and maintenance:

Temperature compensation measures

Software algorithm compensation: Utilize a microprocessor or controller to perform software algorithm compensation on the output signal of the vacuum pressure switch. During the design or use of the switch, by calibrating the switch at different temperatures, the pressure measurement errors corresponding to different temperatures are recorded. Then, based on these calibration data, a temperature compensation algorithm is written. During the actual operation of the switch, the ambient temperature is monitored in real time, and the measured values are corrected according to the algorithm. For instance, when the temperature rises, the measured value of the switch may be higher. The software algorithm will subtract a corresponding correction amount from the measured value based on the pre-set relationship, thereby obtaining a more accurate pressure value.

Hardware circuit compensation: Add a temperature compensation circuit, such as a thermistor compensation circuit, to the switch's circuit. The resistance value of a thermistor changes with temperature. By rationally designing the circuit, the resistance value change of the thermistor can be converted into a change in voltage or current, and then calculated with the pressure signal, thereby achieving compensation for temperature drift. For instance, in a simple voltage comparison vacuum pressure switch, a thermistor can be connected in series. When the temperature changes, the resistance value of the thermistor changes, causing the comparison voltage to change. This, in turn, adjusts the action threshold of the switch, enabling it to operate accurately at different temperatures.

Hardware improvement

Select components with good temperature stability: In the manufacturing process of vacuum pressure switches, electronic components and sensors with small temperature coefficients and good temperature stability should be selected. For instance, pressure sensors with small temperature drift are adopted. These sensors integrate temperature compensation functions internally, which can reduce the influence of temperature on the measurement results to a certain extent. At the same time, choosing high-quality components such as resistors and capacitors, whose performance changes little with temperature, can enhance the stability of the entire switching circuit.

Optimize heat dissipation design: A good heat dissipation design can reduce the temperature variation range of the internal components of the switch, thereby reducing temperature drift. Heat sinks can be added to the switch's housing. The material of the heat sink is usually a metal with good thermal conductivity, such as aluminum alloy. Heat sinks can increase the contact area between the switch and the surrounding environment, accelerating the dissipation of heat. In addition, fan forced cooling can also be adopted. For some vacuum pressure switches with large power or high temperature requirements, installing fans can effectively expel the internal heat and keep the working temperature of the switch stable.

Installation optimization

Control the installation environment temperature: Try to install the vacuum pressure switch in an environment with less temperature variation. Avoid installing it near heat sources (such as heaters, engines, etc.) or cold sources (such as air conditioner vents). If the ambient temperature where the equipment is located cannot avoid significant changes, it is advisable to consider insulation or heat preservation treatment for the switch. For instance, wrap a layer of insulating material such as asbestos or glass fiber around the switch to reduce the impact of external temperature on the switch.

Reasonable layout of circuits: When installing switches, pay attention to the layout of the circuits to avoid generating additional heat that may affect the temperature of the switches. For instance, avoid bundling power lines with signal lines, as power lines generate a certain amount of heat when powered on, which may affect the temperature of the signal lines through heat conduction and thereby impact the measurement accuracy of the switch. At the same time, it is necessary to ensure that the connection of the lines is firm to avoid local heating caused by poor contact.

Regular calibration and maintenance

Regular calibration: As temperature drift is a gradually changing process, even if the above measures have been taken, the vacuum pressure switch still needs to be calibrated regularly. The calibration cycle should be determined based on factors such as the usage frequency of the switch, changes in ambient temperature, and accuracy requirements. Generally speaking, for switches with high precision requirements and large temperature variations in the operating environment, it is recommended to perform calibration every 3 to 6 months. When calibrating, high-precision standard pressure gauges and thermometers should be used to calibrate the switch at different temperature points. Adjust the zero point and range of the switch to make its measured values consistent with the standard values.

Inspection and maintenance: Regularly check whether the appearance of the switch is damaged, whether the connection lines are loose, and whether the heat dissipation components are working properly, etc. If cracks or deformations are found on the switch's housing, it may affect its sealing performance and heat dissipation performance, and it needs to be replaced in time. Meanwhile, the dust and dirt on the surface of the switch should be cleaned to maintain its good heat dissipation conditions. For switches that adopt software compensation, it is also necessary to regularly check whether the compensation algorithm is operating normally. If necessary, update and optimize the algorithm.