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Hangzhou Liance Automation Technology Co., Ltd
Gaochun electromagnetic flowmeter
NegotiableUpdate on 03/10
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Overview
The main device of Gaochun electromagnetic flowmeter $r $n $r $n is the clock provider, which can initiate read or write operations from the slave device. At this point, the master device will have a conversation with a slave device. When there are multiple slave devices on the bus, to initiate a transmission, the master device will pull down the slave device selection line and then start data transmission or reception through MOSI and MISO lines respectively. SPI clock speed is very fast, ranging from a few megahertz to tens of megahertz, and there is no system overhead. The disadvantage of SPI in system management is the lack of flow control mechanism. Both the master and slave devices do not confirm messages, and the master device cannot know from
Product Details
Gaochun electromagnetic flowmeter
The master device is the clock provider and can initiate read or write operations from the slave device. At this point, the master device will have a conversation with a slave device. When there are multiple slave devices on the bus, to initiate a transmission, the master device will pull down the slave device selection line and then start data transmission or reception through MOSI and MISO lines respectively. SPI clock speed is very fast, ranging from a few megahertz to tens of megahertz, and there is no system overhead. The disadvantage of SPI in system management is the lack of flow control mechanism, where both the master and slave devices do not confirm messages, and the master device cannot know whether the slave device is busy. Smart software mechanisms must be designed to handle confirmation issues.
Electromagnetic flowmeters (EMF) are a new type of flow measurement instrument that rapidly developed in the 1950s and 1960s with the advancement of electronic technology. An electromagnetic flowmeter is an instrument that uses the principle of electromagnetic induction to measure the flow rate of a conductive fluid based on the induced electromotive force when the fluid passes through an external magnetic field.
Gaochun electromagnetic flowmeter
The meaning represented by RBW is the difference in bandwidth that can be clearly distinguished between two different frequency signals. Therefore, if the bandwidth of two different frequency signals is lower than the resolution bandwidth of the spectrum analyzer, the two signals will overlap and cannot be distinguished. Such a seemingly lower RBW will help with the resolution and measurement of signals at different frequencies, but a too low RBW may filter out signals at higher frequencies, resulting in distortion during signal display. A higher RBW is certainly helpful for measuring broadband signals, but it may increase the noise floor, reduce measurement sensitivity, and hinder the detection of low-intensity signals.
structure
The structure of an electromagnetic flowmeter mainly consists of a magnetic circuit system, a measuring conduit, electrodes, a housing, a lining, and a converter.
Magnetic circuit system: Its function is to generate a uniform DC or AC magnetic field. The DC magnetic circuit is implemented using magnets, which has the advantages of a relatively simple structure and less interference from AC magnetic fields. However, it can easily polarize the electrolyte liquid inside the measuring tube, causing the positive electrode to be surrounded by negative ions and the negative electrode to be surrounded by positive ions, resulting in electrode polarization and an increase in internal resistance between the two electrodes, which seriously affects the normal operation of the instrument. When the diameter of the pipeline is large, the magnet is also large, bulky, and uneconomical. Therefore, electromagnetic flow meters generally use alternating magnetic fields and are excited by a 50HZ power supply.
Measurement catheter: Its function is to allow the measured conductive liquid to pass through. In order to divert or short-circuit the magnetic flux when the magnetic field lines pass through the measuring conduit, the measuring conduit must be made of non-magnetic, low conductivity, low thermal conductivity, and materials with certain mechanical strength, such as non-magnetic stainless steel, fiberglass, high-strength plastic, aluminum, etc.
Electrode: Its function is to generate an induced potential signal proportional to the measured value. The electrode is generally made of non-magnetic stainless steel and is required to be flush with the lining so that fluid can pass through without obstruction. Its installation position should be in the vertical direction of the pipeline to prevent sediment from accumulating on it and affecting measurement accuracy.
Shell: Made of ferromagnetic material, it is the outer shell of the distribution system excitation coil and isolates the interference of external magnetic fields.
Lining: There is a complete layer of electrical insulation lining on the inner side of the measuring conduit and the flange sealing surface. It directly contacts the liquid being measured, and its function is to increase the corrosion resistance of the measuring conduit and prevent the induced potential from being short circuited by the metal measuring conduit wall. The lining materials are mostly corrosion-resistant, high-temperature resistant, wear-resistant polytetrafluoroethylene plastics, ceramics, etc.
Converter: The induced potential signal generated by liquid flow is very weak and greatly affected by various interference factors. The function of the converter is to amplify and convert the induced potential signal into a unified standard signal and the main interference signal. Its task is to amplify and convert the induced potential signal Ex detected by the electrode into a unified standard DC signal.
However, in the industrial automation applications of CAN bus, due to the increasing demand for device interoperability, an open and standardized high-level protocol is needed: this protocol supports interoperability and interchangeability of various CAN vendor devices, can provide a standardized and unified system communication mode in the CAN network, provide device function description methods, and perform network management functions. This includes the Application layer, which provides a set of useful services and protocols for every active device in the network. Communication profile: provides the meaning of configuring devices and communication data, and defines the data communication method.
feature
1. Measurement is not affected by changes in fluid density, viscosity, temperature, pressure, and conductivity;
2. Measure the flow components inside the tube, with no pressure loss and low requirements for straight pipe sections. Adaptability to slurry measurement;
3. Reasonably selecting sensor lining and electrode materials, which have good corrosion resistance and wear resistance;
4. The converter adopts a novel excitation method, with low power consumption, zero point stability, and high degree. The flow range can reach 150:1;
5. The converter can be integrated or separated from the sensor;
6. The converter adopts a 16 bit high-performance microprocessor, 2x16 LCD display, convenient parameter setting, and reliable programming;
7. The flowmeter is a bidirectional measurement system equipped with three integrators: forward total, reverse total, and differential total; It can display positive and negative flow rates and has multiple outputs: current, pulse, digital communication HART；
8. The converter adopts surface mount technology (SMT) and has self checking and self diagnostic functions;
9. The measurement accuracy is not affected by changes in fluid density, viscosity, temperature, pressure, and conductivity. The sensor's induced voltage signal is linearly related to the average flow rate, resulting in high measurement accuracy.
10. There is no obstruction in the measuring pipeline, so there is no additional pressure loss; There are no movable parts inside the measuring pipeline, so the sensor has an extremely long lifespan.
11. Due to the fact that the induced voltage signal is formed in the entire space filled with a magnetic field and is the average value on the surface of the pipeline, the sensor requires a shorter straight pipe section, with a length of 5 times the diameter of the pipeline.
12. The converter adopts advanced microcontroller (MCU) and surface mount technology (SMT), with reliable performance, high accuracy, low power consumption, stable zero point, and convenient parameter setting. Click on the Chinese display LCD to show cumulative flow, instantaneous flow, flow rate, flow percentage, etc.
13. A bidirectional measurement system that can measure both forward and reverse flow rates. Using special production processes and high-quality materials to ensure the stability of product performance over a long period of time.
Understanding the error of ADC in the system means that designers must understand the type of signal to be sampled. The signal type depends on how the contribution of converter error to the entire system is defined. These converter errors are generally defined in two ways: noiseless code resolution (representing DC class signals) and "signal-to-noise ratio equation" (representing AC class signals). Due to resistance noise and "kT/C" noise, all active devices (such as ADC internal circuits) will generate a certain amount of root mean square (RMS) noise. Even for DC input signals, this noise still exists, which is the reason for the existence of code transition noise in the transfer function of the converter.
Instructions for use
The electromagnetic flowmeter has two operating states: automatic measurement state and parameter setting state.
When the instrument is powered on, it automatically enters the measurement state. In automatic measurement mode, the electromagnetic flowmeter automatically completes various measurement functions and displays corresponding measurement data. In the parameter setting state, the user uses four panel keys to complete the instrument parameter setting.
1. Key function
When the instrument is powered on, it automatically enters the measurement state. In automatic measurement mode, the electromagnetic flowmeter automatically completes various measurement functions and displays corresponding measurement data. In the parameter setting state, the user uses four panel keys to complete the instrument parameter setting.
1. Key function
1.1 Key functions in automatic measurement mode
Down key: Loop through the selection screen to display content in the downward direction;
Up key: Loop through the screen to select the up display content;
Composite key+confirm key: enter parameter setting state;
Confirm button: Return to automatic measurement mode;
Adjustment of LCD display contrast in measurement state: The small LCD is adjusted by pressing the "composite key+up key" or "composite key+down key" for a few seconds; The large LCD is achieved by adjusting the potentiometer on the back of the large LCD.
1.2 Key functions in parameter setting state
Down key: Subtract 1 from the number at the cursor;
Up key: add 1 to the number at the cursor;
Composite key+down key: Move the cursor to the left;
Composite key+up key: Move the cursor to the right;
Confirm key: Enter/Exit submenu;
Confirm button: Press continuously for two seconds in any state to return to automatic measurement mode.
Note: When using the "composite key", you should first press the composite key and then simultaneously hold down the "up key" or "down key"
2. In the parameter setting state, if there is no button operation within 3 minutes, the instrument will automatically return to the measurement state.
3. The flow direction for zero point correction can be selected by moving the cursor to the "+" or "-" on the left and using the "up" or "down" keys to switch it to the opposite direction of the actual flow.
4. To select the unit of flow, you can move the cursor to the original displayed flow unit in the "Flow Range Setting" menu, and then use the "Up" or "Down" keys to switch to meet your needs.
2. Parameter setting function key operation
To set or modify the parameters of an electromagnetic flowmeter, it is necessary to transition the flowmeter from the measurement state to the parameter setting state. In the measurement state, press the "composite key+confirm key" to display the state transition password (0000). According to the confidentiality level, modify the password provided by the manufacturer accordingly. After pressing the "composite key+confirm key" again, it will enter the desired parameter setting state.
Down key: Loop through the selection screen to display content in the downward direction;
Up key: Loop through the screen to select the up display content;
Composite key+confirm key: enter parameter setting state;
Confirm button: Return to automatic measurement mode;
Adjustment of LCD display contrast in measurement state: The small LCD is adjusted by pressing the "composite key+up key" or "composite key+down key" for a few seconds; The large LCD is achieved by adjusting the potentiometer on the back of the large LCD.
1.2 Key functions in parameter setting state
Down key: Subtract 1 from the number at the cursor;
Up key: add 1 to the number at the cursor;
Composite key+down key: Move the cursor to the left;
Composite key+up key: Move the cursor to the right;
Confirm key: Enter/Exit submenu;
Confirm button: Press continuously for two seconds in any state to return to automatic measurement mode.
Note: When using the "composite key", you should first press the composite key and then simultaneously hold down the "up key" or "down key"
2. In the parameter setting state, if there is no button operation within 3 minutes, the instrument will automatically return to the measurement state.
3. The flow direction for zero point correction can be selected by moving the cursor to the "+" or "-" on the left and using the "up" or "down" keys to switch it to the opposite direction of the actual flow.
4. To select the unit of flow, you can move the cursor to the original displayed flow unit in the "Flow Range Setting" menu, and then use the "Up" or "Down" keys to switch to meet your needs.
2. Parameter setting function key operation
To set or modify the parameters of an electromagnetic flowmeter, it is necessary to transition the flowmeter from the measurement state to the parameter setting state. In the measurement state, press the "composite key+confirm key" to display the state transition password (0000). According to the confidentiality level, modify the password provided by the manufacturer accordingly. After pressing the "composite key+confirm key" again, it will enter the desired parameter setting state.
Installation of Intelligent Electromagnetic Flow Meter Sensor on Process Pipeline
1. The intelligent electromagnetic flowmeter blockage tube must be filled with medium at any time and cannot work normally without filling or emptying the tube. When the medium is not fully filled in the pipe, the method of raising the height of the outlet pipe at the back of the flowmeter can be used to fill the pipe with the medium, avoiding the incomplete pipe and gas from adhering to the electrode.
2. Vacuum inside the pipeline can damage the lining of the flowmeter, so special attention should be paid.
3. The positive direction of flow should be consistent with the positive direction indicated by the arrow on the flowmeter.
4. The intelligent electromagnetic flowmeter can be installed on straight pipelines, as well as on horizontal or inclined pipelines, but it requires that the center line of the two electrodes be in a horizontal state.
5. For liquid and solid two-phase fluids, vertical installation is used to allow the measured medium to flow from top to bottom, which can evenly wear the lining of the flowmeter and extend its service life.
6. Ensure that there is sufficient space near the pipeline flange for the installation and maintenance of the flowmeter.
If there is vibration in the measuring pipeline, there should be fixed supports on both sides of the flowmeter.
8. If the measuring medium is a heavily polluted liquid, a flowmeter body can be installed in the bypass pipeline without interrupting the process operation, which can be emptied and cleared.
9. When installing a flow meter with PTFE lining, the bolts connecting the flange should be tightened evenly, otherwise it is easy to crush the PTFE lining. Use a torque wrench.
3. The positive direction of flow should be consistent with the positive direction indicated by the arrow on the flowmeter.
4. The intelligent electromagnetic flowmeter can be installed on straight pipelines, as well as on horizontal or inclined pipelines, but it requires that the center line of the two electrodes be in a horizontal state.
5. For liquid and solid two-phase fluids, vertical installation is used to allow the measured medium to flow from top to bottom, which can evenly wear the lining of the flowmeter and extend its service life.
6. Ensure that there is sufficient space near the pipeline flange for the installation and maintenance of the flowmeter.
If there is vibration in the measuring pipeline, there should be fixed supports on both sides of the flowmeter.
8. If the measuring medium is a heavily polluted liquid, a flowmeter body can be installed in the bypass pipeline without interrupting the process operation, which can be emptied and cleared.
9. When installing a flow meter with PTFE lining, the bolts connecting the flange should be tightened evenly, otherwise it is easy to crush the PTFE lining. Use a torque wrench.
In order to monitor the temperature status of high-voltage power cables in real time, a design scheme for an online monitoring system of high-voltage power cable temperature based on distributed optical fiber sensors is proposed for its high-voltage and strong magnetic field working environment. This scheme adopts fast accumulation of DSP and uses Stokes signals to demodulate Anti Stokes signals, greatly improving the signal-to-noise ratio. In addition, the practical application of the system in power cables is also introduced, and its practical value in the power system is elaborated. With the continuous development of fiber optic sensing technology, single crystal fiber is currently one of the suitable optical waveguide materials for high temperature environments. Its measurement temperature is 2000 ℃, and the temperature resolution is 0.1 ℃. Therefore, using fiber optic sensing technology to design a high-voltage power cable temperature online monitoring system has the characteristics of high accuracy, hardness, flexible bending, small size, and strong resistance to electromagnetic interference.
