Detailed explanation of capacitor switch knowledge

Capacitive switch is a highly intelligent level measurement product. The principle is to use advanced radio frequency capacitance technology to measure the level through the change of several capacitances and have an alarm switch. There are single point, double point, three point and four point options. The

main features of the capacitance switch

are that the data storage technology is used, and the parameters are not lost after power failure, and the data can be saved for up to 10 years.

Using radio frequency capacitance measurement and microcontroller technology, it can detect solid particles, powders and liquids (including conductive media and non-conductive media), especially highly corrosive media; the measurement temperature can reach 180℃, and the pressure resistance can reach 4MPa.

It can overcome the influence of the adhesion layer on the probe and the splashing of materials on the measurement. In these occasions, no false action will occur.

Just press the setting button to complete the setting of the alarm point. The setting button also has anti-vibration characteristics to avoid unnecessary modification of the alarm point.

The upper limit alarm mode and the lower limit alarm mode can be flexibly set.

The probe is protected by polytetrafluoroethylene and is suitable for high temperature and high pressure environments.
 

Main parameters of capacitor switch

Ambient temperature: -30～70℃;

Ambient humidity: ≤95%RH;

Protection level: IP65;

Power supply: 220V.AC±10% or 24V.DC±15%;

Relay contact capacity: 220V.AC/3A or 24V.DC/5A;

Relative dielectric constant: ε≥1.6;

Delay time: 0, 2, 4, 8, 1 6, 3 2 seconds;

Power consumption: ≤1W;

Explosion-proof grade: ExdⅡCT4

Electrical interface: M20×1.5;

Probe length: 350mm or specified by the user;

Process temperature: normal -20～80℃; high temperature -25～180℃;

Process pressure: -0.1～4.0MPa.

The principle of the capacitor switch

The capacitor switch uses radio frequency capacitor technology to convert the level change in the container into the capacitance change. The probe is used as one plate of the capacitor, and the container wall (or auxiliary probe) is used as the other plate. The change of capacitance is converted into the change of pulse frequency through the electronic plug-in. The microcontroller completes the setting of the alarm point and the realization of the alarm action. It overcomes the inconvenience brought to users by the low alarm accuracy and complicated adjustment steps of traditional measurement methods (such as charge and discharge methods, etc.). The alarm point is confirmed by a setting button and the alarm point is stored for a long time. If the alarm point needs to be changed, it can be reset.

Installation of capacitor switch

When installing the capacitor switch, it should be installed top (vertically installed from the top of the warehouse) or side (installed on the side of the warehouse wall) according to the different forms of the probe and the site conditions.

1. When installing from the top, choose a position that can avoid the impact of materials during feeding, and the distance from the silo wall should be greater than 200mm. When installing from the side, it should be tilted downward by 20-30° to avoid serious material hanging on the probe.

2. When disassembling the level switch, do not hold the shell with your hands to twist it, but use a wrench to twist the process connection.

3. When there is no auxiliary probe, ensure that the level switch shell is in good contact with the metal container (<1Ω).

Application of capacitor switches

Capacitor switches are widely used in the measurement and control of liquid, powder and solid levels in the petroleum, chemical, electric power, metallurgy, machinery, food, pharmaceutical, feed and other industries.