How does a radar level gauge work? How to fix the problem?

The electronically controlled level gauge is a kind of measuring equipment that is more common in modern use, which is easy to install and fast, and when purchasing products, you should first understand its working principle and fault handling.

How does a radar level work?

The radar liquid level meter uses ultra-high frequency electromagnetic waves to transmit to the liquid level of the detected container through the antenna, and when the electromagnetic waves are reflected back after touching the liquid level, the instrument measures the time difference between the transmitted wave and the echo, so as to calculate the liquid level height. The better the conductivity of the dielectric or the greater the dielectric constant of the dielectric medium, the better the reflection of the echo signal.

Radar level gauges are mainly composed of transceiver devices. Signal Processor. Antenna. Console. The display is composed of several parts. Radio-reflective reception is the basis of the work of radar level gauges. The method is divided into time difference and frequency difference.

In the time difference type, the transmission frequency is fixed, and the operating time of the transmitted and reflected waves is measured, and then the measured liquid level height is measured by the intelligent signal processor. The working time and liquid level distance of this type of radar level gauge are: t=2d/c. where C is the electromagnetic wave propagation velocity, C=300000km/s; d represents the distance between the liquid level of the measured medium and the probe; t represents the time from the emission of the electromagnetic wave to the receipt of the reflected electromagnetic wave.

The frequency difference method is to measure the frequency difference between the transmitted wave and the reflected wave, and convert this frequency difference into a telecommunication signal proportional to the measured liquid surface. The emission frequency of this level gauge is not a fixed frequency, but a frequency with a first-order adjustable amplitude.

Introduction to the components of the radar level gauge.

1. The antenna is the key component of the radar level gauge, and the shape of the antenna determines its focus and sensitivity.

2. The bell mouth antenna is suitable for most occasions, and the focusing characteristics are especially good. This type of antenna is used by many oil tanks, but is not suitable for the measurement of corrosive media.

3. The pole antenna mounting flange has small size, good chemical stability, easy to clean, and is not sensitive to the adhesion of condensate, especially suitable for measuring corrosive media such as sulfur and narrow installation short pipes for high-precision measurement.

4. The lower flange type antenna is suitable for high temperature media. Corrosive media or environments where the top cannot be mounted.

5. The parabolic antenna has good focusing, is not affected by heated vapor, and is especially suitable for measuring large containers with heated vapor in the tank, such as residual oil, asphalt, etc.

How to deal with common faults of radar level gauges

First, the problem of the level gauge itself.

1. If the instrument fails in hardware, it should be replaced by software audit.

2. When the current signal is greater than 22mA or 0mA, the electronic components are mostly damaged when the instrument is replaced, and it is recommended to replace the instrument or repair it in time.

The 3.4-20 mA signal is unstable, which may be due to the fluctuation of the instrument’s level.

4. When the signal of the level gauge is 4-20mA, it is the signal loss, which is caused by the misconnection of the power supply.

Second, there is a false echo phenomenon in the bypass tube radar level gauge.

Due to the presence of burrs on the wall of the bypass pipe. Welding slag. Impurities such as welds and attachments have detectable false echo signals, which affect the detection of real echo signals and lead to false liquid levels in radar level gauges. The use of computer software to store and eliminate false echoes is only a temporary practice, and in order to completely solve the problem of false echoes showing false liquid levels in radar level gauges, it is necessary to clean and frost the bypass pipe.

3. The instrument is not tightly sealed, resulting in the failure of the instrument circuit.

Most of the instrument circuit failures are due to cable inlets. The meter cover is not tightly sealed so that rain or other liquids are imposed. Dust. Caused by moisture entering the inside of the meter. Therefore, when purchasing, we must give priority to the radar level gauge with good sealing, and pay attention to the correct installation, and if necessary, install a protective cap for the instrument to seal the entire instrument.

Antenna scarring has an impact on the accurate measurement of radar level gauges.

Hanging materials with a very small dielectric constant have no effect on the measurement in the dry state, while hanging materials with a high dielectric constant have a greater impact on the measurement. In this case, the antenna scarring can be eliminated by purging with compressed air or rinsing with clean water, or by regularly washing the scarring with an acidic cleaning solution.