A liquid level gauge sensor short circuit, open circuit detection circuit

Abstract

The invention provides a short circuit and open circuit detection circuit for a liquid level meter sensor. The detection circuit comprises an amplifier A1, an amplifier A2, a summator, a comparator I,a comparator II, an OR logic gate, an analog switch and / or a V / I conversion circuit, wherein the amplifier A1 is connected with a first detection point and a second detection point; the amplifier A2is connected with the second detection point and a third detection point; the output voltage of the amplifier A1 and the amplifier A2 is input into the summator to be subjected to summation; the output end of the summator is independently connected with the first input end of the comparator I and the first input end of the comparator II; the output end of the comparator I is connected with the first input end of the OR logic gate; the output end of the comparator II is connected with the second input end of the OR logic gate; the output end of the OR logic gate is connected with the first input end of the analog switch; the output end of the amplifier A2 is connected with the second input end of the analog switch; the first output end of the analog switch is connected with the V / I conversion circuit; and the second output end of the analog switch outputs alarm voltage VA.

Description

technical field [0001] The invention belongs to the field of measurement, and in particular relates to a short-circuit and open-circuit detection circuit of a liquid level gauge sensor. Background technique [0002] Resistive sensors are used in magnetic float level gauge circuits such as figure 1 As shown, R1, R2...RN is the sensor resistance network, where R1 represents the position of the highest point of the liquid level, RN represents the position of the lowest point of the liquid level, and the reed switch at the corresponding position of S1, S2...SN, the liquid level reaches the corresponding After the position, the corresponding dry reed switch is turned on. The constant current source current flows from T1 to T3, and a differential voltage is drawn from T2 and T3 points. The larger the differential voltage, the closer the conducting reed switch is to T1, which in turn indicates the higher the liquid level. [0003] The traditional resistance magnetic float level g...

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Problems solved by technology

[0004] The principle of this method is simple and the components are simplified, but it does not take into account the fault conditions, such as short circuit between T1 and T2, or short circuit between T3 and T2, and the abnormal situation when any resistor in the resistor network is open. The application cannot be used, so it is necessary to increase the sensor failure alarm circuit to improve the reliability of the measurement system

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