Capacitive - Miniature Current Sensor - Supply [Weckway]

Temperature versus capacitancecurrent sensor The impact

1. Impact on structural dimensions

The change in ambient temperature will cause changes in the geometric dimensions and mutual geometric positions of various parts of the capacitive sensor, resulting in changes in the courtyard or area between the capacitor plates and additional capacitance changes. This applies to capacitive capacitors with variable gapssensorIt is more important because the gap is usually very small, about tens to hundreds of micrometers. To reduce this error, in the manufacturing of capacitivesensorGenerally, materials with low temperature coefficient and stable geometric dimensions are selected. If the electrode bracket is made of ceramic material and the electrode material is made of iron nickel alloy. In recent years, spraying a layer of metal on ceramics or quartz as an electrode has been more effective.

2. Influence on dielectric constant

传感器The capacitance value of the sensor is directly proportional to the dielectric constant of the medium. Therefore, if the dielectric constant of the medium has a non-zero temperature coefficient, it will inevitably cause a change in the sensor capacitance value, resulting in additional temperature errors. The temperature coefficient of the dielectric constant of air and mica can be considered equal to zero; Some liquid media, such as silicone oil, castor oil, methyl silicone oil, and kerosene, must pay attention to the errors caused by this.

This temperature error can be compensated for to some extent by the subsequent measurement circuit, but it is difficult to completely eliminate it.