超声波变送器 10. Ultrasonic Transmitter
Ultrasonic transmitters are divided into general ultrasonic transmitters (without meter heads) and integrated ultrasonic transmitters;
Chemical ultrasonic transmitters are more commonly used.
The integrated ultrasonic variable updater consists of a meter head (such as an LCD display) and a probe; this direct input
The transmitter with a 4-20 mA signal is assembled with a miniaturized sensitive element (probe) and electronic circuit;
And make it smaller, lighter and cheaper.
Ultrasonic transmitters can be used for level.
Level measurement and open channel, open channel and other flow measurement, and can be used to measure distance.
锑电极酸度变送器 11. Antimony electrode acidity transmitter
Antimony electrode acidity transmitter is an industrial online analysis instrument that integrates PH detection, automatic cleaning, and electrical signal conversion. It is a PH value measurement system composed of antimony electrode and reference electrode.
In the tested acidic solution, as the antimony trioxide oxide layer will be formed on the surface of the antimony electrode, a potential difference will be formed between the antimony metal surface and antimony trioxide.
The magnitude of this potential difference depends on the concentration of antimony trioxide in Sansho, which corresponds to the moderate level of hydrogen ions in the acid solution being measured.
If the appropriate amounts of antimony, antimony trioxide, and aqueous solutions are taken as 1, the electrode potential can be calculated using the Nernst formula.
The solid module circuit in the antimony electrode acidity transmitter consists of two parts. For the sake of safety in the field, the power supply uses AC 24V to power the secondary instrument.
In addition to providing driving power for the cleaning motor, this power supply should also be converted into the corresponding DC voltage by the current conversion unit for use in the transmission circuit.
The second part is the measurement transmitter circuit, which sends the reference signal and PH acidity signal from the sensor to the slope adjustment and positioning adjustment circuit after being amplified, so that the internal resistance of the signal can be reduced and adjusted.
The amplified PH signal and the temperature compensated signal are added to the conversion circuit, and finally a 4-20mA constant current signal corresponding to the PH value is output to the secondary meter to complete the display and control the PH value.
电导变送器 12. Conductivity transmitter
It is a process instrument (integrated transmitter) that measures the ion concentration indirectly by measuring the conductivity of the solution.
The conductivity of aqueous solutions in industrial processes can be continuously measured online.
Because the electrolyte solution is a good conductor of electricity like the metal conductor, there must be a resistance effect when the current flows through the electrolyte solution, and it complies with Ohm's law.
However, the resistance temperature characteristic of a liquid is opposite to that of a metal conductor, and it has a negative temperature characteristic. To distinguish it from metal conductors, the conductivity of an electrolyte solution is expressed by conductivity (reciprocal of resistance) or conductivity (reciprocal of resistivity).
When two mutually insulated electrodes form a conductivity cell, if a solution to be measured is placed in the middle and a constant voltage alternating current is passed, a current loop is formed.
If the voltage and electrode size are fixed, there is a certain function relationship between the loop current and the conductivity. In this way, the electrical conductivity of the test solution can be measured by measuring the current flowing in the test solution.
The structure and circuit of the conductivity transmitter are the same as those of the acid, alkali and salt concentration transmitters.
酸、碱、盐浓度变送器 13.Acid , alkali and salt concentration transmitter
Acid, alkali, and salt concentration transmitters determine the concentration by measuring the conductivity of the solution. It can continuously detect the concentration content of acid, alkali and salt in aqueous solution in the industrial process. This transmitter is mainly used in industrial production processes such as boiler feedwater treatment, chemical solution preparation and environmental protection.
The working principle of acid, alkali and salt concentration transmitter is: within a certain range, the concentration of acid and alkali solution is proportional to the size of its conductivity. Therefore, as long as the conductivity of the solution is measured, the level of the acid-base concentration can be known.
When the measured solution flows into the dedicated conductivity cell, if you ignore the electrode polarization and distributed capacitance, it can be equivalent to a pure resistance.
When a constant voltage alternating current flows, its output current has a linear relationship with the conductivity, and the conductivity is proportional to the acid and alkali concentration in the solution.
Therefore, as long as the solution current is measured, the concentration of acid, alkali and salt can be calculated.
The acid, alkali and salt concentration transmitters are mainly composed of a conductivity cell, an electronic module, a display head and a housing.
The electronic module circuit is composed of excitation power supply, conductance cell, conductance amplifier, phase-sensitive rectifier, demodulator, temperature compensation, overload protection and current conversion.
The intelligent transmitter is made up of a sensor and a microprocessor (microcomputer) phase structure.
It makes full use of the computing and storage capabilities of the microprocessor to process the sensor's data, including the conditioning of measurement signals (such as filtering, amplification, A / D conversion, etc.), data display, automatic correction, and automatic compensation.
The microprocessor is the heart of the smart transmitter. It can not only calculate, store and process the measurement data, but also adjust the sensors through the feedback loop to make the collected data optimal.
Because the microprocessor has a variety of software and hardware functions, it can accomplish tasks that traditional transmitters can't do.
Therefore, the intelligent transmitter reduces the manufacturing difficulty of the sensor and improves the performance of the sensor in a large range.
In addition, the intelligent transmitter also has the following characteristics:
具有自动补偿能力，可通过软件对传感器的非线性、温漂、时漂等进行自动补偿。 a. It has automatic compensation capability, which can automatically compensate the sensor's non-linearity, temperature drift, and time drift through software.
可自诊断，通电后可对传感器进行自检，以检查传感器各部分是否正常，并作出判断。 b. Self-diagnosis. After power-on, the sensor can be self-checked to check whether each part of the sensor is normal and make a judgment.
数据处理方便准确，可根据内部程序自动处理数据，如进行统计处理、去除异常数值等。 c. The data processing is convenient and accurate, and the data can be automatically processed according to internal procedures, such as statistical processing and removal of abnormal values.
具有双向通信功能。 d. With two-way communication function. The microprocessor can not only receive and process the sensor data, but also feed back the information to the sensor to regulate and control the measurement process.
可进行信息存储和记忆，能存储传感器的特征数据、组态信息和补偿特性等。 e. Information storage and memory can be carried out, which can store the sensor's characteristic data, configuration information and compensation characteristics.
具有数字量接口输出功能，可将输出的数字信号方便地和计算机或现场总线等连接。 f. It has a digital interface output function, which can easily connect the output digital signal to a computer or field bus.