CN219164544U - A characteristic signal transmitting circuit of a measuring switch - Google Patents

Abstract

The utility model relates to a characteristic signal transmitting circuit of a measuring switch. The phase line L of the mains is connected to the fuse F1, the other end of F1 is connected to R4, the other end of R4 is connected to the AC input end of the rectifier bridge D2, the other AC input end of D2 is connected to the neutral line N, the phase line L is connected to the The varistor RV1 is connected in parallel between the neutral line N; the positive output terminal of the rectifier bridge D2 is connected to R1, and the other end of R1 is connected to the cathode of the Zener diode D1, and the capacitor C1 is connected in parallel to D1, and the cathode of the Zener diode leads to a 12V power supply; The photodiode anode of the coupling ISO1 is connected to the PWM signal of the microcontroller, the collector of the phototransistor of ISO1 is connected to the 12V power supply, the emitter of the phototransistor of ISO1 is connected to the resistor R10; the emitter of the photodiode of the optocoupler ISO1 is connected to the base of the triode T1 through R6 The emitter of the phototransistor of the optocoupler ISO1 is also connected to the base of the transistor T3, the collector of T1 is connected to the 12V power supply, the collector of T3 is connected to the signal ground through R13, the emitters of T1 and T3 are connected, and connected to the resistors R11, Diode D3 cathode connection.

Description

A characteristic signal transmitting circuit of a measuring switch

technical field

The utility model belongs to the technical field of transmitting circuits, in particular to a characteristic signal transmitting circuit of a measuring switch.

Background technique

With the construction of smart grid and the continuous improvement of users' requirements for power quality, how to improve the reliability of power supply and production management level of distribution network has become a major issue in front of the power industry. To solve this problem, the electric power department needs to strengthen fine-grained management, and the accurate power supply relationship of household substations in the station area is the basis for realizing fine-grained management of electric power companies. Due to the temporary change of the line in some station districts, the record of household transformer power supply relationship was wrong, etc., resulting in abnormal line loss during the assessment station district. In addition, the phase sequence relationship between the low-voltage user equipment and the branch line is not clear, which leads to problems such as difficult maintenance and positioning after a power outage occurs.

The existing household transformer power supply relationship topology identification is mainly to inject a characteristic current signal into the power grid at the meter box, usually near the zero-crossing signal, and the transformer or branch switch box monitors this characteristic current signal, and then judges the meter box and The relationship between transformers and branch boxes.

In the prior art, when the characteristic current signal is injected, the current transmission is mainly realized through switching devices such as thyristors, and the transmission signal is a current pulse signal, and the signal is generally transmitted near the zero-crossing signal, and the pulse current transmission is realized by shorting the LN.

This solution has relatively high requirements for judging the switching time point. Once the switching time is wrong, it is easy to generate a large current, generate a large amount of heat, and easily damage the device; in addition, the circuit structure of the sending module in the prior art is complex, and peripheral circuits such as zero-crossing circuits are required. It generates a lot of heat and has extremely high requirements on switching devices, so the cost is high, and its volume is large, which is not conducive to integration.

Therefore, the existing characteristic current signal sending circuit has a large volume and high cost and is not suitable for measuring switches.

Utility model content

Aiming at the above problems, the utility model provides a characteristic signal transmitting circuit applied to a measuring switch with simple structure, stable operation and small volume.

The utility model adopts the following technical solutions: a characteristic signal transmitting circuit of a measuring switch, including a single-chip microcomputer and a fuse F1, which is characterized in that the phase line L of the commercial power is connected with the fuse F1, and the other end of the fuse F1 is connected with a current-limiting resistor R4 is connected, the other end of the current limiting resistor R4 is connected to an AC input terminal of the rectifier bridge D2, the other AC input terminal of the rectifier bridge D2 is connected to the neutral line N, and the varistor RV1 is connected in parallel between the phase line L and the neutral line N ;

The negative output terminal of the rectifier bridge D2 is connected to the signal ground, the positive output terminal of the rectifier bridge D2 is connected to the resistor R1, the other end of the resistor R1 is connected to the cathode of the Zener diode D1, the anode of the Zener diode D1 is connected to the signal ground, and the Zener diode D1 has a capacitor C1 in parallel, and the cathode of the Zener diode leads to a 12V power supply;

The anode of the photodiode of the optocoupler ISO1 is connected to the PWM signal of the microcontroller, the collector of the phototransistor of the photocoupler ISO1 is connected to the 12V power supply, the emitter of the phototransistor of the photocoupler ISO1 is connected to the resistor R10, and the other end of the resistor R10 is connected to the signal ground;

The phototransistor emitter of the optocoupler ISO1 is connected to the base of the triode T1 through the resistor R6, the phototransistor emitter of the optocoupler ISO1 is also connected to the base of the triode T3, the collector of the triode T1 is connected to the 12V power supply, and the collector of the triode T3 The electrodes are connected to the signal ground through the resistor R13, the emitters of the triode T1 and the triode T3 are connected, and are connected with the resistor R11 and the cathode of the diode D3.

Preferably, the other end of the resistor R11 is connected to the gate of the MOS transistor Q1, the gate of the MOS transistor Q1 is also connected to the resistor R7, and the other end of the resistor R7 is connected to the anode of the diode D3.

Preferably, the positive output terminal of the rectifier bridge D2 is also connected to the drain of the MOS transistor Q1, the source of the MOS transistor Q1 is connected to the signal ground through the resistor R; the drain of the MOS transistor Q1 is connected to the signal ground through the resistor R5 and the capacitor C2 Signal ground connection.

Preferably, the MOS transistor Q1 is an N-channel MOS transistor with a model of 2N90.

The circuit of the utility model is simple and reliable, and has fewer components, small volume and low heat generation, and is easy to be highly integrated in a measuring switch, has low material cost, and is convenient to be widely used in low-voltage metering boxes.

Description of drawings

Fig. 1 is the schematic circuit diagram of the utility model.

Implementation

Below in conjunction with specific embodiment, further set forth the utility model.

As shown in Figure 1, the utility model discloses a characteristic signal transmitting circuit of a measuring switch, the phase line L of the commercial power is connected to the fuse F1, the other end of the fuse F1 is connected to the current limiting resistor R4, and the current limiting resistor R4 The other end of the rectifier bridge D2 is connected to an AC input terminal, the other AC input terminal of the rectifier bridge D2 is connected to the neutral line N, and the varistor RV1 is connected in parallel between the phase line L and the neutral line N.

The positive output terminal of the rectifier bridge D2 is connected to the resistor R1, the other end of the resistor R1 is connected to the cathode of the Zener diode D1, the anode of the Zener diode D1 is connected to the signal ground, the Zener diode D1 is connected in parallel with a capacitor C1, and the cathode of the Zener diode leads to 12V power supply.

The positive output terminal of the rectifier bridge D2 is also connected to the drain of the MOS transistor Q1, the source of the MOS transistor Q1 is connected to the signal ground through the resistor R; the drain of the MOS transistor Q1 is connected to the signal ground through the resistor R5 and the capacitor C2.

The single chip microcomputer outputs PWM signal according to the parameters such as carrier frequency and duty ratio of the characteristic signal, and the PWM signal is connected with the photodiode anode of the optocoupler ISO1. The phototransistor collector of the optocoupler ISO1 is connected to the 12V power supply, the phototransistor emitter of the optocoupler ISO1 is connected to the resistor R10, and the other end of the resistor R10 is connected to the signal ground. The phototransistor emitter of the optocoupler ISO1 is connected to the base of the triode T1 through the resistor R6, and the phototransistor emitter of the optocoupler ISO1 is also connected to the base of the triode T3. The collector of the transistor T1 is connected to the 12V power supply, and the collector of the transistor T3 is connected to the signal ground through the resistor R13. The emitters of the triode T1 and the triode T3 are connected, and are connected with the resistor R11 and the cathode of the diode D3. The other end of the resistor R11 is connected to the gate of the MOS transistor Q1, the gate of the MOS transistor Q1 is also connected to the resistor R7, and the other end of the resistor R7 is connected to the anode of the diode D3,

When the PWM signal of the microcontroller is at a positive level, the photodiode of the optocoupler ISO1 is turned on, so that the phototransistor of the optocoupler ISO1 is turned on. The emitter of the phototransistor of the optocoupler ISO1 is extremely high level, the triode T1 is turned on, T2 is cut off, and the emitters of the triode T1 and T3 output high level. The output high level of the emitters of the transistors T1 and T3 is divided by the resistors R11 and R14 and then connected to the gate of the MOS transistor Q1.

The MOS tube has three working areas, which are the load stop area, the variable resistance area and the constant current area. When the MOS is in the constant current region, it is equivalent to a resistor with a large resistance in the on state, which can bear part of the power. Therefore, allowing the MOS to work in the constant current region when it is turned on can reduce the power withstand of the resistor and reduce the size of the circuit. Reasonable adjustment of the voltage division ratio of the resistors R11 and R14 makes the gate voltage of the MOS transistor Q1 about 5V, and the MOS transistor Q1 works in a constant current region with a constant current of about 450mA.

When the PWM signal of the microcontroller is at low level, the photodiode of the optocoupler ISO1 is cut off, so the phototransistor of the optocoupler ISO1 is turned off. The emission of the phototransistor of the optocoupler ISO1 is extremely low, the triode T3 is turned on, T1 is cut off, and the emitters of the triodes T1 and T3 output low level. The diode D3 is turned on, and the resistors R7 and R11 are connected in parallel at this time, which accelerates the discharge of the gate voltage of the MOS transistor and turns it into a low level so that the MOS transistor Q1 is turned off.

Due to the large size and high cost of the existing characteristic current signal sending circuit, it is not suitable for measuring switches. With the construction of the smart grid, new measurement switches are widely used in low-voltage metering boxes. The measurement switch integrates a high-precision current sensor and a measurement unit, and is extremely compact.

The circuit of the utility model is simple and reliable, has few components, small volume, low heat generation, is easy to be highly integrated in the measuring switch, and is convenient to be widely used in low-voltage metering boxes.

It should be understood that these embodiments are only used to illustrate the present utility model and are not intended to limit the scope of the present utility model. In addition, it should be understood that after reading the content taught by the utility model, those skilled in the art can make various changes or modifications to the utility model, and these equivalent forms also fall within the scope defined by the appended claims of the application.

Claims (4)

1. The characteristic signal transmitting circuit of the measuring switch comprises a singlechip and a fuse F1, and is characterized in that a phase line L of mains supply is connected with the fuse F1, the other end of the fuse F1 is connected with a current limiting resistor R4, the other end of the current limiting resistor R4 is connected with one alternating current input end of a rectifier bridge D2, the other alternating current input end of the rectifier bridge D2 is connected with a zero line N, and a piezoresistor RV1 is connected in parallel between the phase line L and the zero line N;

the negative output end of the rectifier bridge D2 is connected with signal ground, the positive output end of the rectifier bridge D2 is connected with a resistor R1, the other end of the resistor R1 is connected with the cathode of a voltage-stabilizing diode D1, the anode of the voltage-stabilizing diode D1 is grounded, the voltage-stabilizing diode D1 is connected with a capacitor C1 in parallel, and the cathode of the voltage-stabilizing diode is led out of a 12V power supply;

the anode of the light diode of the optical coupler ISO1 is connected with a PWM signal of the singlechip, the collector of the phototriode of the optical coupler ISO1 is connected with a 12V power supply, the emitter of the phototriode of the optical coupler ISO1 is connected with a resistor R10, and the other end of the resistor R10 is connected with a signal ground;

the emitter of the phototriode of the optocoupler ISO1 is connected with the base of the triode T1 through a resistor R6, the emitter of the phototriode of the optocoupler ISO1 is also connected with the base of the triode T3, the collector of the triode T1 is connected with a 12V power supply, the collector of the triode T3 is grounded through a resistor R13, and the emitters of the triode T1 and the triode T3 are connected and connected with a resistor R11 and the cathode of a diode D3.

2. The characteristic signal transmitting circuit of a measuring switch according to claim 1, wherein the other end of the resistor R11 is connected to the gate of the MOS transistor Q1, the gate of the MOS transistor Q1 is further connected to the resistor R7, and the other end of the resistor R7 is connected to the anode of the diode D3.

3. The characteristic signal transmitting circuit of a measuring switch according to claim 1 or 2, wherein the positive output end of the rectifier bridge D2 is further connected to the drain electrode of the MOS transistor Q1, and the source electrode of the MOS transistor Q1 is connected to the signal ground through a resistor R; the drain electrode of the MOS tube Q1 is connected with signal ground through a resistor R5 and a capacitor C2.

4. The characteristic signal transmitting circuit of a measuring switch according to claim 2, wherein the MOS transistor Q1 is an N-channel MOS transistor, and the model number is 2N90.

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