Intelligent molded case circuit breaker with measurement function

Abstract

The application provides a smart molded case circuit breaker with a measuring function, which comprises a current transformer for detecting the working condition of the circuit breaker in real time, a release for automatically disconnecting the circuit breaker, and a transformer connected with a three-phase alternating current power supply, the output end of the transformer is connected with the release and a voltage stabilizing chip U1 respectively, the output end of the current transformer is divided into two branches after passing through a rectifier bridge and a power supply circuit in sequence, one of the two branches is connected with the release after passing through a first diode D1, the other branch is connected with the input end of the voltage stabilizing chip U1 after passing through a second diode D2, a third diode D3 is arranged between the output end of the transformer and the input end of the voltage stabilizing chip U1, the output end of the voltage stabilizing chip U1 is connected with the input end of a voltage stabilizing chip U2, the application can still complete the detection of the current under low load, the product function is more perfect, and the power supply for the controller is more stable and reliable than the traditional single current transformer sensing voltage.

Description

Technical Field

[0001] The invention belongs to the technical field of power-off protection, and in particular relates to an intelligent molded case circuit breaker with a measuring function. Background Art

[0002] At present, traditional intelligent molded case circuit breakers (hereinafter referred to as circuit breakers) are composed of a contact system, a detection system, a controller unit, an actuator, an arc extinguishing system, etc. When the current transformer of the detection system detects an abnormality (such as overload or short circuit), the controller unit analyzes and judges the current and sends a trip signal to the actuator to trip the circuit breaker to protect electrical equipment from damage. However, the existing traditional circuit breakers have the following disadvantages: First, when the load is lower than 0.2In, the current transformer cannot detect any signal and the controller does not work. Second, the existing circuit breaker cannot display the system current and voltage online. Third, the existing circuit breaker cannot detect system voltage abnormalities and provide real-time protection. Summary of the Invention

[0003] In order to solve the above technical problems, the present invention provides an intelligent molded case circuit breaker with a measurement function. The circuit breaker can still complete the current detection work under low load. The product function is more complete and more stable and reliable than the traditional controller power supply that relies solely on the induced voltage of the current transformer.

[0004] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: an intelligent molded case circuit breaker with a measurement function, comprising a current transformer for real-time detection of the working condition of the circuit breaker, a trip device for automatically disconnecting the circuit breaker, and a transformer connected to a three-phase AC power supply, wherein the output end of the transformer is respectively connected to the trip device and the voltage regulator chip U1, and the output end of the current transformer is divided into two branches after passing through a rectifier bridge and a power supply circuit in sequence, one of which is connected to the trip device after passing through a first diode D1, and the other branch is connected to the input end of the voltage regulator chip U1 after passing through a second diode D2, a third diode D3 is arranged between the output end of the transformer and the input end of the voltage regulator chip U1, and the output end of the voltage regulator chip U1 is connected to the input end of the voltage regulator chip U2.

[0005] Furthermore, the power supply circuit includes resistors R1-R7, a fourth diode D4, a voltage-stabilizing diode ZD1, a field-effect transistor Q1, a filter capacitor C1, and a voltage comparator U3. The output end of the current transformer is connected to the cathode of the voltage-stabilizing diode ZD1 and one end of the resistor R7 after the rectifier bridge. The other end of the resistor R7 is connected to the drain of the field-effect transistor Q1. The source of the field-effect transistor Q1 is grounded, the gate of the field-effect transistor Q1 is connected to the anode of the voltage-stabilizing diode ZD1, the anode of the voltage-stabilizing diode ZD1 is connected to the cathode of the fourth diode D4, a resistor R6 is connected in series between the source and gate of the field-effect transistor Q1, the anode of the fourth diode D4 is connected to the output end of the voltage comparator U3, and the in-phase input of the voltage comparator U3 is connected. The input end is grounded through the resistor R3, the inverting input end of the voltage comparator U3 is respectively connected to one end of the resistor R1 and one end of the resistor R2, the other end of the resistor R1 is connected to the cathode of the voltage stabilizing diode ZD1, the other end of the resistor R2 is grounded and connected to the cathode of the filter capacitor C1, the positive electrode of the filter capacitor C1 is respectively connected to the positive electrode of the first diode D1, the positive electrode of the second diode D2 and the inverting input end of the voltage comparator U3, the positive electrode of the voltage comparator U3 is respectively connected to the output end of the voltage stabilizing chip U1 and one end of the resistor R4, the negative electrode of the voltage comparator U3 is grounded, the other end of the resistor R4 is connected to the non-inverting input end of the voltage comparator U3, and a resistor R5 is connected in series between the output end and the inverting input end of the voltage comparator U3.

[0006] Furthermore, each phase of the three-phase AC power supply is connected to the AD port of the single chip microcomputer through a voltage dividing resistor.

[0007] Furthermore, the input port of the single chip microcomputer is connected to the current transformer, the output port of the single chip microcomputer is connected to the trip unit and the liquid crystal driver chip respectively, and the liquid crystal driver chip is connected to the liquid crystal display.

[0008] Furthermore, the input port of the single chip microcomputer is also connected to a plurality of buttons.

[0009] Furthermore, the output end of the voltage stabilizing chip U2 is connected to several indicator lights.

[0010] Furthermore, the cathode of the first diode D1 is connected to the trip unit, and the cathodes of the second diode D2 and the third diode D3 are both connected to the input end of the voltage stabilizing chip U1.

[0011] Furthermore, the first diode D1 , the second diode D2 and the third diode D3 are all composed of a plurality of diodes connected in parallel.

[0012] Furthermore, the model of the voltage regulator chip U1 is 78L05, and the model of the voltage regulator chip U2 is HT7533.

[0013] Compared with the existing technology, the beneficial effects of the present invention are: the present invention adds voltage power supply, voltage protection and online current and voltage display functions on the basis of the existing circuit breaker, and the beneficial effects are mainly manifested in the following aspects: 1. The present invention adds an independent circuit for power supply to the single-chip microcomputer, which is more stable and reliable than the traditional method of relying solely on the current transformer to sense the voltage to power the single-chip microcomputer, ensuring that the single-chip microcomputer can work reliably when the load is very small; 2. The present invention adds voltage detection and voltage protection functions to make the protection function more complete; 3. The present invention is provided with a human-computer interaction interface, which improves the operability of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a principle block diagram of the present invention;

[0015] Figure 2 A circuit diagram of the power supply circuit of the present invention;

[0016] Figure 3 A circuit diagram of several indicator lights in the present invention;

[0017] Figure 4 This is a schematic diagram of the structure of the liquid crystal driver chip in the present invention;

[0018] Figure 5 Schematic diagram of the structure of the liquid crystal display of the present invention;

[0019] Figure 6 This is a circuit diagram of several buttons in the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0021] like Figure 1As shown, an intelligent molded case circuit breaker with a measurement function includes a current transformer for real-time detection of the working status of the circuit breaker, a trip device for automatically disconnecting the circuit breaker, and a transformer connected to a three-phase AC power supply. The output ends of the transformer are respectively connected to the trip device and the voltage regulator chip U1. The three-phase AC power supply is stepped down by the transformer to power the trip device and the voltage regulator chip U1. It should be noted here that if the transformer has only one output end, the trip device and the voltage regulator chip are in a parallel relationship. In order to achieve the best use effect, the transformer can have two output ends, one of which outputs a +13V voltage to directly power the trip device, and the other output outputs a +30 to 35V voltage to power the voltage regulator chip U1. The voltage output from the output end of the current transformer is divided into two branches after passing through a rectifier bridge and a power supply circuit. The rectifier bridge is a prior art in this field. While not described in detail here, one branch is connected to the trip unit via a first diode D1, and the other branch is connected to the input of a voltage regulator chip U1 via a second diode D2. A third diode D3 is provided between the transformer output and the input of voltage regulator chip U1, connecting the output of voltage regulator chip U1 to the input of voltage regulator chip U2. Further optimizing this solution, voltage regulator chip U1 is a 78L05 with a +5V output voltage, while voltage regulator chip U2 is an HT7533 with a +3.3V output voltage. The present invention divides the power supply for the trip unit into two parts: one is self-generated by the current transformer, and the other is powered by a three-phase AC power supply after voltage reduction by a transformer. The three-phase AC power supply is drawn from the incoming line of the circuit breaker, increasing the power supply voltage and ensuring reliable operation of the controller and trip unit even under low load conditions. The self-generated power supply from the current transformer ensures normal operation of the controller and trip unit even when the power supply voltage is abnormal. These two power supply methods do not conflict and provide excellent functional protection.

[0022] like Figure 2As shown, the power supply circuit includes resistors R1-R7, a fourth diode D4, a voltage-stabilizing diode ZD1, a field-effect transistor Q1, a filter capacitor C1 and a voltage comparator U3. The filter capacitor C1 is an electrolytic capacitor. The output end of the current transformer is connected to the cathode of the voltage-stabilizing diode ZD1 and one end of the resistor R7 after the rectifier bridge. The other end of the resistor R7 is connected to the drain of the field-effect transistor Q1. The source of the field-effect transistor Q1 is grounded, the gate of the field-effect transistor Q1 is connected to the anode of the voltage-stabilizing diode ZD1, the anode of the voltage-stabilizing diode ZD1 is connected to the cathode of the fourth diode D4, a resistor R6 is connected in series between the source and the gate of the field-effect transistor Q1, the anode of the fourth diode D4 is connected to the output end of the voltage comparator U3, the non-inverting input end of the voltage comparator U3 is grounded through the resistor R3, and the voltage comparator U3 is grounded. The inverting input terminal of the voltage comparator U3 is respectively connected to one end of the resistor R1 and one end of the resistor R2. The other end of the resistor R1 is connected to the cathode of the voltage stabilizing diode ZD1. The other end of the resistor R2 is grounded and connected to the cathode of the filter capacitor C1. The positive electrode of the filter capacitor C1 is respectively connected to the anode of the first diode D1, the anode of the second diode D2, and the inverting input terminal of the voltage comparator U3. The positive electrode potential of the filter capacitor C1 is +13V, and the +13V voltage directly powers the trip unit. The positive electrode of the voltage comparator U3 is respectively connected to the output terminal of the voltage stabilizing chip U1 and one end of the resistor R4. The negative electrode of the voltage comparator U3 is grounded. The other end of the resistor R4 is connected to the non-inverting input terminal of the voltage comparator U3. A resistor R5 is connected in series between the output terminal and the inverting input terminal of the voltage comparator U3.

[0023] The voltage at pin 13 of the voltage comparator U3 is a voltage obtained by dividing the +5V voltage through resistors R3 and R4. The voltage at pin 12 of the voltage comparator U3 is a voltage obtained by dividing the voltage output by resistors R1 and R2 after rectification of the current transformer. The output of pin 14 is achieved by comparing the voltages at pins 12 and 13 of the voltage comparator U3. When pin 14 is at a high level, the drain and source of the field-effect transistor Q1 are turned on to discharge current, thereby stabilizing the voltage output by the current transformer after rectification within a certain range, thereby improving the stability and safety of the present invention.

[0024] Each phase of the three-phase AC power supply is connected to the AD port of the single-chip microcomputer after passing through a voltage-dividing resistor. The voltage-dividing resistor is not drawn in the figure. The A, B, and C three-phase voltages are divided by the voltage-dividing resistor and enter the AD port of the single-chip microcomputer. The single-chip microcomputer can calculate the current A, B, and C three-phase voltage values. Based on the voltage values ​​and the set values, overvoltage, undervoltage, phase failure, and total voltage loss protection are performed. The voltage protection process of the present invention is specifically as follows:

[0025] ① Overvoltage protection: The microcontroller measures the RMS value of the primary circuit voltage (i.e., the three-phase voltages A, B, and C). When any phase voltage exceeds the overvoltage protection set value (e.g., 285V, adjustable as needed), an alarm or trip is triggered. ② Undervoltage protection: When any phase voltage falls below the action threshold (e.g., 165V, adjustable as needed), an alarm or trip is triggered. ③ Phase failure protection: When any phase voltage falls below the action threshold (e.g., 120V, adjustable as needed), an alarm or trip is triggered. ④ Total loss of voltage protection: An alarm or trip is triggered in the event of a power outage.

[0026] The input port of the single chip microcomputer is connected to the current transformer, the output port of the single chip microcomputer is connected to the trip unit and the liquid crystal driver chip respectively, the liquid crystal driver chip is connected to the liquid crystal display, the model of the liquid crystal driver chip is HT1621B, and the model of the liquid crystal display is BL3151W1. Figure 4 and Figure 5 As shown, the pins 28-48 of the LCD driver chip are connected to the pins 5-25 of the LCD display in descending order, the pins 13-16 of the LCD driver chip are connected to the pins 1-4 of the LCD display in descending order, the pins 1-4 of the LCD driver chip are connected to the output port of the microcontroller, the pin 5 of the LCD driver chip is grounded, the pins 6, 7, 10-12, and 17-27 of the LCD driver chip are vacant, the pin 8 of the LCD driver chip is connected to the pin 9 through the resistor R8, and the liquid crystal is connected to the pin 10. Pin 9 of the crystal driver chip is connected to the +3.3V voltage, that is, the output end of the voltage regulator chip U2; the LCD display also includes a backlight driver module, specifically pins 26 and 27, among which pin 26 is connected to the +3.3V voltage, that is, the output end of the voltage regulator chip U2 after passing through resistor R10, and pin 27 is connected to the output port of the microcontroller after passing through transistor Q2 and resistor R9 in turn. The model of transistor Q2 is SS8050, its base is connected to resistor R9, the collector is connected to pin 27, and the emitter is grounded.

[0027] like Figure 6 As shown, the input port of the single chip microcomputer is also connected to several keys, namely K1-K4, which correspond to the shift, increment, menu and return keys respectively.

[0028] like Figure 3 As shown, the output end of the voltage regulator chip U2 is connected to several indicator lights, namely LED1-3, which correspond to the status, alarm and communication indicator lights respectively. The several indicator lights are connected to the output end of the voltage regulator chip U2 after a protection resistor. The output voltage of the voltage regulator chip U2 is +3.3V.

[0029] The display and menu operation of the present invention is composed of a liquid crystal display, three indicator lights LED1-3 and four buttons K1-K4. The liquid crystal display is used to display voltage, current value and menu settings, and the indicator lights are used to indicate the operating status.

[0030] The cathode of the first diode D1 is connected to the trip unit, and the cathodes of the second diode D2 and the third diode D3 are connected to the input end of the voltage regulator chip U1. To further optimize this solution, the first diode D1, the second diode D2 and the third diode D3 are all composed of multiple parallel diodes.

[0031] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An intelligent molded case circuit breaker with measurement function, comprising a current transformer for real-time detection of the circuit breaker's operating status, a trip unit for automatically disconnecting the circuit breaker, and a transformer connected to a three-phase AC power supply, characterized in that: The output end of the transformer is respectively connected to the release and the voltage regulator chip U1. The output end of the current transformer is divided into two branches after passing through the rectifier bridge and the power supply circuit. One branch is connected to the release after passing through the first diode D1, and the other branch is connected to the input end of the voltage regulator chip U1 after passing through the second diode D2. A third diode D3 is provided between the output end of the transformer and the input end of the voltage regulator chip U1. The output end of the voltage regulator chip U1 is connected to the input end of the voltage regulator chip U2. The power supply circuit includes resistors R1-R7, a fourth diode D4, a voltage-stabilizing diode ZD1, a field-effect transistor Q1, a filter capacitor C1, and a voltage comparator U3. The output end of the current transformer is connected to the cathode of the voltage-stabilizing diode ZD1 and one end of the resistor R7 respectively after passing through a rectifier bridge. The other end of the resistor R7 is connected to the drain of the field-effect transistor Q1. The source of the field-effect transistor Q1 is grounded. The gate of the field-effect transistor Q1 is connected to the anode of the voltage-stabilizing diode ZD1. The anode of the voltage-stabilizing diode ZD1 is connected to the cathode of the fourth diode D4. A resistor R6 is connected in series between the source and gate of the field-effect transistor Q1. The anode of the fourth diode D4 is connected to the output end of the voltage comparator U3. The non-inverting input end of the voltage comparator U3 is connected via a resistor R6. The resistor R3 is grounded, the inverting input terminal of the voltage comparator U3 is respectively connected to one end of the resistor R1 and one end of the resistor R2, the other end of the resistor R1 is connected to the cathode of the voltage stabilizing diode ZD1, the other end of the resistor R2 is grounded and connected to the cathode of the filter capacitor C1, the anode of the filter capacitor C1 is respectively connected to the anode of the first diode D1, the anode of the second diode D2 and the inverting input terminal of the voltage comparator U3, the anode of the voltage comparator U3 is respectively connected to the output terminal of the voltage stabilizing chip U1 and one end of the resistor R4, the negative electrode of the voltage comparator U3 is grounded, the other end of the resistor R4 is connected to the non-inverting input terminal of the voltage comparator U3, and a resistor R5 is connected in series between the output terminal and the inverting input terminal of the voltage comparator U3; Each phase of the three-phase AC power supply is connected to the AD port of the single-chip microcomputer after passing through a voltage divider resistor; the input port of the single-chip microcomputer is connected to the current transformer, and the output port of the single-chip microcomputer is respectively connected to the release and the liquid crystal driver chip, and the liquid crystal driver chip is connected to the liquid crystal display; the first diode D1, the second diode D2, and the third diode D3 are all composed of multiple parallel diodes.

2. The intelligent molded case circuit breaker with measurement function according to claim 1, characterized in that: The model of the voltage regulator chip U1 is 78L05, and the model of the voltage regulator chip U2 is HT7533.

Images