The difference between the tuning fork level switch and the RF conduction sodium level switch

The tuning fork can only be used as a level switch, which triggers the switch by detecting changes in the frequency and amplitude of the vibration. Radio frequency sodium is a method of measuring admittance with high frequency current. This can be done as a switch or as a continuous measurement.
The tuning fork works by vibrating the tuning fork at a certain resonant frequency through a pair of piezoelectric crystals mounted on the base of the tuning fork. When the tuning fork is in contact with the measured medium. The amplitude and frequency of the tuning fork will be abrupt, and the intelligent circuit will detect this and convert this change into a switching signal.
How does radiofrequency conduction work?
The RF admittance level control technology is developed from the capacitive level control technology. The anti-hanging material (the material adhered by the sensor is called the hanging material) has better performance, more reliable work, more accurate measurement and more applicability. Wide level control technology, "admittance" in "radio admittance" means the reciprocal of impedance in electricity, which is composed of resistive, capacitive and inductive components, and "radio frequency" is high frequency. Therefore, the RF admittance technique can be understood as a method of measuring admittance with high frequency current.
The important difference between point-to-bit RF admittance technology and capacitor technology is the use of three-terminal technology and the diversity of measurement parameters. The measurement signal at the center of the circuit unit is connected to the center line of the coaxial cable and then connected to the center of the sensor. At the same time, the coaxial cable shielding layer is suspended at a level that is very small and very stable, but is equal to the measurement signal equipotential, in phase, and frequency, but has no direct electrical relationship, that is, the level of isolation from each other. The signal passes through a non-inverting amplifier with a gain of "1" and a strong driving capability. The output is connected to the coaxial cable shield and then to the sensor's shield. The ground wire is another separate wire in the cable. Since the center line of the coaxial cable has the above relationship with the outer shield, there is no potential difference between the two, and no current flows, that is, no current leaks from the center line, which is equivalent to no capacitance or capacitance between the two. Equal to zero. Therefore, the temperature effect of the cable, the installation capacitance, etc. will not affect.
For the problem of the influence of the hanging material on the sensor, a new sensor structure, a five-layer concentric structure, and a sensor structure are used: * The inner layer is the center probe, the middle is the shielding layer, and the outer surface is the grounding mounting thread, which will be insulated with an insulating layer. They are isolated separately. The same as the case of the coaxial cable, there is no potential difference between the center probe and the shielding layer. Even if the resistance of the hanging material on the sensor is small, no current will flow. The electronic instrument measures only from the center of the sensor to the opposite tank. The current of the wall (ground), because the shielding layer can block the current from flowing back to the container wall along the sensor, so the ground current can only pass through the measured material to the opposite container wall through the sensor end.
That is, U center probe = U shield, I center probe pair shield = (U center probe - U shield) × YL = 0. Although there is a potential difference between the shield layer and the vessel wall, a current flows between the two, but the current is not measured and does not affect the measurement result. This protects the measuring end from the influence of the hanging material. Only when the material in the container rises into contact with the center probe, the measured current can be formed between the center probe and the ground through the material to be tested, and the instrument detects the current and generates an effective output signal.
The RF admittance technology introduces measurement parameters other than capacitance, especially the resistance parameters, which makes the signal-to-noise ratio of the meter measurement signal increase, which greatly improves the resolution, accuracy and reliability of the instrument. The diversity of measurement parameters also has Vigorously expand the reliable application of the instrument.