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Structure of Generator Set Liquid Level Sensor

Feb. 01, 2023

The generator set level sensor can observe the oil level in the oil pan, the coolant level in the radiator, the fuel level in the fuel tank and the electrolyte level in the battery. So, do you know what kinds of structure types of generator set liquid level sensor have? The liquid level sensor of the generator set mainly includes five different ways. The starlight power generation equipment shares the details as follows.

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1. Float-type liquid level sensor

(1) Float-reed switch type float reed switch type liquid level sensor is mainly composed of resin hollow shaft tube with flashing reed switch and ring float embedded with magnet. There are two thin metal contacts in the reed switch. When the liquid level is lower than the specified position, the float and the embedded magnet move downward to approach the reed switch. The magnetic lines of the reed switch increase, the two contacts attract each other and close, the circuit is connected, and the warning lamp lights up for warning. When the liquid level is at the specified position, the float moves up, no magnetic wire passes through the reed switch, the contact opens under its own elastic force, and the instrument stops prompting. This type of sensor is usually used for detection of coolant level, lubricating oil level, etc.

(2) Float-variable resistance type variable resistance type liquid level sensor is composed of a float body with sliding resistance inside and a float arm connecting the two. The float in the sensor can move up and down with the liquid level, and change the resistance value of the resistor by sliding the sliding arm on the resistance, and use the change of the resistance value to control the size of the current in the circuit through the instrument display or send the signal to the diesel engine controller. This sensor is mostly combined with the fuel gauge, and the generator set factory is often used to detect the fuel quantity (level) in the fuel tank.

2. Thermistor type liquid level sensor

It is mainly composed of sensor body and thermistor, which is mainly used to detect the fuel level in the fuel tank. Its working process is to apply voltage to the thermistor, and under the action of electrified current, it will heat itself. When the thermistor is immersed in the fuel, the temperature does not rise due to the rapid heat dissipation, and the resistance value is high; On the contrary, when the thermistor is exposed to the air, its resistance value decreases due to slow heat dissipation and temperature rise. The generator set manufacturer can use this principle to connect it in the circuit to detect the fuel level in the fuel tank, which is usually connected with the level warning lamp.

3. Electrode type liquid level sensor

The electrode type liquid level sensor is composed of lead rod electrode and phase circuit, and is mainly used to detect the electrolyte level (liquid volume) in the battery. When the electrolyte level in the battery meets the specified value, the end of the lead rod of the sensor is immersed in the electrolyte, the electromotive force is generated on the lead rod, and the triode π is connected. At this time, the potential of point A is close to zero, the triode π is in the cut-off state, and the warning light is not on. When the electrolyte level in the battery is lower than the specified value, the electrolyte is separated from the end of the lead rod of the sensor, the lead rod is no longer immersed in the electrolyte, no electromotive force is generated on the lead rod, and the triode π is cut off; At this time, the potential of point A rises, the transistor T2 is on, and the warning lamp is on. Inform that the amount of electrolyte in the battery is insufficient and should be added.

4. Capacitive liquid level sensor

The capacitance level sensor converts the liquid level into the change of capacitance, and then calculates the liquid level by measuring capacitance. It works according to the principle of cylindrical capacitor. The sampling parts of the capacitive sensor are two metal concentric cylinders coated with insulating paint, which are used as the inner and outer electrodes of the capacitor.

If the liquid level height h in the cylindrical capacitive sensor changes, the total dielectric constant between the two poles of the capacitive liquid level sensor changes, and the capacitance value of the sensor also changes. The liquid level height of the material can be calculated by measuring the capacitance value at this time. From the above formula, it can be seen that there is a linear relationship between the height h of the liquid level and the capacitance value. The sensitivity of the capacitive liquid level sensor mainly depends on the difference between the two dielectric constants. Common capacitance sensor measurement circuits include transformer bridge type, operational amplifier type and pulse width type. This type of sensor is suitable for continuous measurement of liquid level and position-type measurement. The capacitance level meter for position-type measurement should be of vertical installation type, and the capacitance level meter for continuous measurement should be of horizontal installation type.

Because the dielectric constant of water is much greater than that of air, the capacitance of the capacitance sensor will be significantly larger when it is immersed in water. This feature can be used to measure the water level. The sensor capacitance and resistance form an R oscillation circuit. When the capacitance increases, the circuit impedance decreases, and the current flowing is large. Take out the corresponding current change to determine the water level. If any question please feel free to visit our website https://www.dieselgeneratortech.com/ or send email to sales@dieselgeneratortech.com.

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