In recent years, with the continuous development of electronic technology and automation, liquid level measurement and control technology has been greatly improved. The production of daily chemicals, food and beverage, medicine and other industries cannot do without liquid level monitoring. The importance of liquid level sensors is becoming more and more prominent, and even directly affects the quality of products. Therefore, a correct understanding of the wiring method of the liquid level sensor can reduce the error of the liquid level sensor in the operation process, otherwise it will easily cause the damage of the liquid level sensor and affect the accuracy of the measurement. Therefore, the wiring method of the liquid level sensor is very important for our use. So how to wire the level sensor? Next, I will introduce how to wire the liquid level sensor.
Liquid level sensor is a common sensor for measuring liquid level position, which converts the height of the position into an electrical signal for output. The liquid level sensor is a modular circuit, which has the advantages of acid resistance, moisture resistance, shock resistance, corrosion resistance, etc. The circuit contains a constant current feedback circuit and an internal protection circuit, which can make the maximum output current not exceed 28mA, so it can reliably protect the power supply and make the secondary The meter is not damaged.
Liquid level sensor, the general output signal is current 4-20MA, 0-20MA, or voltage 0-5V, 1-5V, 0-10V, etc., usually current type is two-wire or four-wire system, voltage three-wire system output. At present, many of them do not have a 24VDC power supply, most of which are 10V. Some transmitters with larger power consumption cannot be driven by a 10VDC power supply, so they can only be externally powered by 24VDC. In this way, the liquid level sensor has four terminals: power supply +, power supply -, feedback + and feedback -.
The current-type two-wire connection ratio of the liquid level sensor wiring: power supply +== power supply+; signal +== feedback+, power supply -== feedback -, if it is not remote, just connect 24V voltage +, -, if it needs to be remote Transmission needs to form a loop, such as 24V+ connected to pressure gauge+, pressure gauge- connected to 4-20mA+, 4-20mA- connected to 24V-, there may be terminals in the middle, please look at the circuit diagram.
The voltage type three-wire wiring method of the liquid level sensor wiring: power supply +== power supply +; power supply-(signal -) = = power supply -; signal + = = feedback +, power supply-(signal -).
The four-wire wiring method of liquid level sensor wiring: power supply +== power supply+; power supply -== power supply-; signal +== feedback+, signal -==feedback-.
Speaking of this, some people will ask why the principle of the liquid level switch and the liquid level sensor are the same, and why the wiring method of the liquid level switch is different? That's because the liquid level switch is a controller that opens the water discharge or water inlet valve according to the signal output of the liquid level sensor to keep the water level constant. It can also be said that the output of the liquid level switch is a switch signal. The liquid level switch must first determine the height of the liquid level, and output the switch signal according to this height. The liquid level sensor converts the height of the liquid level into an electrical signal for output. We can process electrical signals such as connecting with plc, data collector or professional display to output the height of liquid level. In addition, the principle of the liquid level switch and the liquid level sensor is the same. But the liquid level switch is a switch control circuit, and the liquid level sensor is equivalent to a circuit component for voltage and current conversion.
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