Correct wiring method of liquid level sensor

Liquid level sensor (hydrostatic level gauge/liquid level transmitter/liquid level sensor/water level sensor) is a pressure sensor that measures liquid level. The static pressure input liquid level sensor (liquid level gauge) is based on the principle that the static pressure of the measured liquid is proportional to the height of the liquid. It is an electrical signal, which is then converted into a standard electrical signal (usually 4~20mA/1~5VDC) after temperature compensation and linear correction.

In the production process of daily chemicals, food and beverage, medicine and other industries, liquid level monitoring is inseparable. The importance of liquid level sensors is becoming more and more prominent, and even directly affects the quality of products. Only by correctly understanding the wiring method of the liquid level sensor can the error of the liquid level sensor during operation be reduced, otherwise it will easily lead to the damage of the liquid level sensor and affect the accuracy of the measurement. The following will introduce to you how to wire the liquid level sensor.

The liquid level sensor is a common sensor that measures the liquid level position. It 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 and corrosion resistance. 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 the current type is two-wire or four-wire, voltage three-wire output. At present, many of them do not have 24VDC power supply, most of them are 10V, and some transmitters with high power consumption cannot be driven by the 10VDC power supply, so only an external power supply of 24VDC can be used. In this way, the liquid level sensor has four terminals: power supply +, power supply -, feedback + and feedback -.

The current type two-wire connection method of the liquid level sensor wiring: power supply +== power supply +; signal + = feedback +, power supply - = feedback-, if it is not remote transmission, only need to connect 24V voltage +, -, if you need remote transmission The transmission needs to form a circuit, for example, 24V+ is connected to pressure gauge+, pressure gauge- is connected to 4-20mA+, and 4-20mA- is connected to 24V-. There may be terminals in the middle. Please see 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-.

When it comes to this, some people will ask why the principle of the liquid level switch and the liquid level sensor is the same, and why the wiring method of the liquid level switch will be different? That is because the liquid level switch is a kind of 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 to plc, data collector or professional display to output the height of the liquid level. There is the principle of the liquid level switch and the liquid level sensor although the same. However, the liquid level switch is a switch control circuit, and the liquid level sensor is a circuit element equivalent to a voltage change and a current change.