A time delay leakage protector

Abstract

The application discloses a time-delay leakage protector, which comprises a zero sequence transformer, a leakage detection circuit, a time-delay voltage detection circuit and a tripping driving circuit; the secondary side of the zero sequence transformer is connected with the input end of the leakage detection circuit, the output end of the leakage detection circuit is connected with the input end of the time-delay voltage detection circuit, and the output end of the time-delay voltage detection circuit is connected with the tripping driving circuit; the time-delay voltage detection circuit has a time-delay threshold value; when the electric signal generated by the zero sequence transformer meets the leakage threshold value of the leakage detection circuit, the leakage detection circuit sends a signal to the time-delay voltage detection circuit, and the time-delay voltage detection circuit turns on the tripping driving circuit after the time-delay threshold value; and the application has the characteristics of leakage time-delay.

Description

Technical Field

[0001] This application relates to the field of low-voltage electrical equipment, and specifically to a time-delayed residual current device. Background Technology

[0002] A residual current device (RCD), also known as a residual current circuit breaker, is a protective device to prevent electric shock accidents. It is installed in the power grid. When the leakage current in the power grid exceeds a set value, the protector disconnects the circuit or sends an alarm signal to ensure the safety of people and the circuit.

[0003] Depending on their role in the selective protection design of the power grid, residual current devices (RCDs) can be divided into upstream RCDs and downstream RCDs. An upstream RCD can be understood as the main switch for downstream RCDs, and often one upstream RCD corresponds to multiple downstream RCDs.

[0004] If the circuit breaker does not have a time delay protection function, both the upstream and downstream circuit breakers will trip when they detect a leakage in the line. In other words, if a leakage occurs in a branch, the upstream leakage protection device will also trip, causing other branches (other branches without leakage) to lose power at the same time, which will undoubtedly result in a great waste of resources.

[0005] The time delay function of existing residual current devices is basically implemented using dedicated chips, which is not cost-effective.

[0006] Therefore, how to design a more cost-effective residual current device with leakage current delay function is a question worth considering. Summary of the Invention

[0007] In view of this, the purpose of this application is to overcome the shortcomings of the prior art and to provide a time-delayed leakage current protection device with leakage current delay characteristics.

[0008] This application provides a time-delayed leakage current protector, comprising a zero-sequence current transformer, a leakage current detection circuit, a time-delayed voltage detection circuit, and a tripping drive circuit. The secondary side of the zero-sequence current transformer is connected to the input terminal of the leakage current detection circuit, the output terminal of the leakage current detection circuit is connected to the input terminal of the time-delayed voltage detection circuit, and the output terminal of the time-delayed voltage detection circuit is connected to the tripping drive circuit. The time-delayed voltage detection circuit has a time-delay threshold. When the electrical signal induced by the zero-sequence current transformer meets the leakage current threshold of the leakage current detection circuit, the leakage current detection circuit sends a signal to the time-delayed voltage detection circuit, and the time-delayed voltage detection circuit conducts the tripping drive circuit after passing the time-delay threshold.

[0009] In some embodiments of this application, the delayed voltage detection circuit includes a voltage detector U2, which has a built-in delayed threshold; the output of the leakage current detection circuit and one end of the tripping drive circuit are respectively connected to different pins of the voltage detector U2.

[0010] In some embodiments of this application, the delayed voltage detection circuit includes a voltage detector U2 and a first capacitor, the capacitance of which determines the delay threshold; the output terminal of the leakage current detection circuit, one end of the tripping drive circuit, and the first end of the first capacitor are connected to different pins of the voltage detector U2, and the second end of the first capacitor is grounded.

[0011] In some embodiments of this application, the number of first capacitors is at least two, and the capacitance value of each first capacitor is different, the capacitance value of the first capacitor determines the delay threshold; the second terminal of all first capacitors is grounded; the delay voltage detection circuit further includes a switching switch SW2, one end of the switching switch SW2 is connected to the pin of the voltage detector U2, and the other end of the switching switch SW2 is connected to the first terminal of any first capacitor; when the switching switch SW2 selects different first capacitors, the corresponding delay threshold is different.

[0012] In some embodiments of this application, the delayed voltage detection circuit further includes a diode D17, which is connected between the trip drive circuit and the pin of the voltage detector U2.

[0013] In some embodiments of this application, the delayed voltage detection circuit further includes a capacitor C9, one end of which is grounded, and the other end of which is connected to the pin of the voltage detector U2 and the output terminal of the leakage current detection circuit.

[0014] In some embodiments of this application, a power supply circuit and a step-down circuit are also included; one end of the power supply circuit is connected to the main line, and the other end is connected to the step-down circuit. The other end of the step-down circuit is connected to the leakage current detection circuit. The voltage of the main line is supplied to the leakage current detection circuit after passing through the power supply circuit and the step-down circuit.

[0015] In some embodiments of this application, the tripping drive circuit includes a tripping coil KM, a silicon controlled rectifier (SCR) Q1, a SCR Q2, a resistor R4, and a diode D14. One end of the tripping coil KM is connected to the power supply circuit, and the other end of the tripping coil KM is connected to the anode of the SCR Q1 and one end of the step-down circuit. The control electrode of the SCR Q1 is connected to one end of the resistor R4, and the other end of the resistor R4 is connected to the cathode of the diode D14. The anode of the diode D14 is connected to the other end of the step-down circuit. The cathode of the SCR Q1 is connected to the anode of the SCR Q2, and the control electrode of the SCR Q2 is connected to the output terminal of the delay voltage detection circuit.

[0016] In some embodiments of this application, the leakage current detection circuit includes a leakage current detection chip U1 and a signal conditioning circuit. The signal conditioning circuit is connected between the input pin of the leakage current detection chip and the secondary side of the zero-sequence current transformer, and the input terminal of the delay voltage detection circuit is connected to the output pin of the leakage current detection chip.

[0017] The advantages of this application compared to the prior art are:

[0018] The delayed voltage detection circuit formed by the voltage detector in this application has a simpler circuit structure and higher cost performance compared with the prior art (which is a dedicated leakage delay chip). Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A block diagram of a time-delay leakage current protector according to an embodiment of this application is shown;

[0021] Figure 2 A circuit diagram of one embodiment of the time-delay leakage current protection device according to this application is shown;

[0022] Figure 3 A circuit diagram of another embodiment of the time-delay leakage current protection device according to the present application is shown. Detailed Implementation

[0023] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0024] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0026] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0027] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature. Example

[0028] like Figure 1-3 As shown, an embodiment of this application is a time-delay leakage current protector, including a power supply circuit 100, a step-down circuit 110, a zero-sequence current transformer CT1, a leakage current detection circuit 120, a time-delay voltage detection circuit 130, and a tripping drive circuit 140. All connections mentioned in this application are electrical connections, referring to circuit connections, and will not be elaborated further below.

[0029] The power supply circuit 100 includes a surge protection circuit and a rectifier bridge. The surge protection circuit is connected between the input terminal of the rectifier bridge and the main line, and the output terminal of the rectifier bridge is connected to the step-down circuit 110. Here, the surge protection circuit includes varistors RV1, RV2, and RV3, which are respectively connected between the three-phase power supplies A, B, and C and the input terminal of the rectifier bridge to provide surge protection.

[0030] The rectifier bridge, consisting of a full-wave rectifier circuit composed of diodes D1, D4, D5, D8, D9, and D12, rectifies the voltages from the three-phase power supplies A, B, and C and outputs them to the trip drive circuit 140 and the step-down circuit 110.

[0031] A step-down circuit 110 is connected between the output of the rectifier bridge and the leakage current detection circuit 120. It steps down the rectified voltage to provide the operating voltage for the leakage current detection circuit 120. Here, the step-down circuit 110 uses resistor R5. To ensure a more stable voltage that meets the requirements of the leakage current detection circuit 120, a Zener diode Z1 and a capacitor C8 are also connected between the step-down circuit 110 and the leakage current detection circuit 120. One end of the Zener diode Z1 is grounded, and the other end is connected to both the leakage current detection circuit 120 and the step-down circuit 110, thus providing voltage regulation. One end of the capacitor C8 is grounded, and the other end is connected to both the leakage current detection circuit 120 and the step-down circuit 110, thus providing filtering.

[0032] The secondary side of the zero-sequence current transformer CT1 is connected to the input terminal of the leakage current detection circuit 120, the output terminal of the leakage current detection circuit 120 is connected to the input terminal of the delayed voltage detection circuit 130, and the output terminal of the delayed voltage detection circuit 130 is connected to the tripping drive circuit 140.

[0033] The trip drive circuit 140 includes a trip coil KM, silicon controlled rectifiers Q1 and Q2, a resistor R4, and a diode D14. One end of the trip coil KM is connected to the output of the rectifier bridge, and the other end is connected to the anode of silicon controlled rectifier Q1 and one end of resistor R5. The control electrode of silicon controlled rectifier Q1 is connected to one end of resistor R4, one end of resistor R4 is connected to the cathode of diode D14, and the anode of diode D14 is connected to the other end of resistor R5. The cathode of silicon controlled rectifier Q1 is connected to the anode of silicon controlled rectifier Q2, the control electrode of silicon controlled rectifier Q2 is connected to the output of the time-delay voltage detection circuit 130, and the cathode of silicon controlled rectifier Q2 is grounded. When the output of the time-delay voltage detection circuit 130 receives a signal, silicon controlled rectifier Q2 and silicon controlled rectifier Q1 conduct (that is, the trip drive circuit 140 conducts), and the voltage across the trip coil KM is sufficient to trip the residual current device (RCD) (the trip coil KM is the trip unit of the RCD). Of course, the thyristor here actually functions as an electronic switch, and a MOSFET can be used as a replacement.

[0034] Here, in order to reduce high voltage spikes, the trip drive circuit 140 also includes a freewheeling diode D13, and the trip coil KM is connected in parallel with the freewheeling diode D13.

[0035] Here, in order to prevent overvoltage from damaging the thyristors, the trip drive circuit 140 also includes a varistor RV5, which is connected in parallel with the series branch of thyristors Q1 and Q2.

[0036] Here, the trip drive circuit 140 also includes a capacitor C5, one end of which is connected to the cathode of the thyristor Q2, and the other end is connected to the control electrode of the thyristor Q2.

[0037] Here, the leakage current detection circuit 120 includes a leakage current detection chip U1 and a signal conditioning circuit. The signal conditioning circuit is connected between the input pin of the leakage current detection chip and the secondary side of the zero-sequence current transformer CT1, and the input terminal of the delayed voltage detection circuit 130 is connected to the output pin of the leakage current detection chip.

[0038] The signal conditioning circuit here includes resistor R1, bidirectional diode D16, resistors R2 and R3, capacitors C1, C6, and C7. The two ends of resistor R1 are connected to the two ends of the secondary side of the zero-sequence current transformer CT1. One end of bidirectional diode D16 is connected to one end of resistor R1 and one end of resistor R2; the other end of bidirectional diode D16 is connected to the other end of resistor R1 and one end of resistor R3. The other end of resistor R2 is connected to one end of capacitor C7 (the other end of capacitor C7 is grounded), one end of capacitor C1, and pin 1 of the leakage current detection chip U1. The other end of resistor R3 is connected to one end of capacitor C6 (the other end of capacitor C6 is grounded), the other end of capacitor C1, and pin 2 of the leakage current detection chip U1.

[0039] The induced signal from the zero-sequence current transformer CT1 is processed by the signal conditioning circuit and then output to the leakage current detection chip U1.

[0040] The 8th pin of the leakage current detection chip U1 is connected to the capacitor C8. The voltage of the three-phase power supply (main line) is rectified, stepped down, regulated and filtered before being supplied to the leakage current detection chip U1.

[0041] Pin 7 of the leakage current detection chip U1 is connected to the input terminal of the delayed voltage detection circuit 130. When there is leakage current in the main line, the induced signal of the zero-sequence transformer CT1 is processed by the signal conditioning circuit and then input to the leakage current detection chip U1 through pin 1 and pin 2 (also known as the input pin). The leakage current detection chip U1 determines whether the input signal reaches the leakage threshold (the set value inside the leakage current detection chip U1). If the leakage threshold is reached, a signal is output to the delayed voltage detection circuit 130 through pin 7 (also known as the output pin).

[0042] Pin 3 of the leakage current detection chip U1 is grounded.

[0043] Pin 5 of the leakage current detection chip U1 is connected to one end of capacitor C2, and the other end of capacitor C2 is grounded.

[0044] Pin 6 of the leakage current detection chip U1 is connected to one end of capacitor C3, and the other end of capacitor C3 is grounded.

[0045] The delayed voltage detection circuit 130 has a delayed threshold. When the electrical signal induced by the zero-sequence current transformer meets the leakage threshold of the leakage current detection circuit, the leakage current detection circuit sends a signal to the delayed voltage detection circuit. After the delayed voltage detection circuit passes the delayed threshold, the tripping drive circuit is activated. If the delayed time has not reached the delayed threshold, the electrical signal induced by the zero-sequence current transformer CT1 is less than the leakage threshold of the leakage current detection circuit 120. The leakage current detection circuit 120 no longer sends a signal to the delayed voltage detection circuit 130, and the delayed voltage detection circuit 130 stops the delayed action and no longer outputs a signal to activate the tripping drive circuit 140.

[0046] The delay voltage detection circuit 130 includes a voltage detector U2, which is used to realize the leakage delay function. Compared with the existing technology that uses a dedicated leakage delay chip, this method has a better cost performance and a simpler circuit structure.

[0047] like Figure 2 As shown, specifically, the delayed voltage detection circuit 130 includes a voltage detector U2 and a first capacitor C001. The output terminal of the leakage current detection circuit, one end of the tripping drive circuit, and the first terminal of the first capacitor C001 are respectively connected to different pins of the voltage detector U2, and the second terminal of the first capacitor C001 is grounded. Here, the capacitance value of the first capacitor C001 will determine the delay threshold.

[0048] As an alternative, in addition to being externally placed in voltage detector U2, the first capacitor C001 can also be a voltage detector U2 with a built-in fixed delay threshold, which can also achieve the leakage delay function. There are many options for this type of voltage detector U2 with a built-in delay threshold, such as the ME2815 series voltage detector.

[0049] like Figure 3 As shown, as a more preferred embodiment, the delay voltage detection circuit 130 includes four different delay threshold levels, meaning the delay threshold is adjustable. Of course, in addition to the four different delay threshold levels, more or fewer levels can be set, but at least two different delay threshold levels are sufficient.

[0050] The adjustable delay voltage detection circuit 130 includes a voltage detector U2, a switching switch SW2, and grade branches corresponding to different delay thresholds. Each grade branch has a capacitor, namely, first capacitor C001, first capacitor C101, first capacitor C201, and first capacitor C301. The capacitance value of each capacitor is different, thus making the delay thresholds different as well. The second terminals of first capacitors C001, C101, C201, and C301 are grounded.

[0051] Here, pin 1 of voltage detector U2 is connected to pin 7 of leakage current detection chip U1 to receive signals from leakage current detection chip U1.

[0052] Pin 5 of voltage detector U2 is connected to the control electrode of thyristor Q2. When the delay threshold of voltage detector U2 is reached (provided that voltage detector U2 receives a signal from leakage current detection chip U1), it controls thyristor Q2 to conduct.

[0053] Pin 3 of voltage detector U2 is grounded.

[0054] The fourth pin of the voltage detector U2 is connected to one end of the switch SW2, and the other end of the switch SW2 is used to connect to the gear branch.

[0055] Here, the other end of SW2 is used to connect to different gear positions, and only one gear position can be connected at a time. The switch SW2 can be configured in various ways, such as using a DIP switch, encoder, etc.

[0056] Regardless of the method used in the above-mentioned delay voltage detection circuit, it includes diode D17. The positive terminal of diode D17 is connected to pin 5 of voltage detector U2, and the negative terminal of diode D17 is connected to the control terminal of thyristor Q2.

[0057] Regardless of the method used in the above-mentioned delay voltage detection circuit, it includes capacitor C9. One end of capacitor C9 is grounded, and the other end of capacitor C9 is connected to pin 1 of voltage detector U2 and pin 7 of leakage current detection chip U1, which serves as a filter.

[0058] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0059] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A time-delay residual current device, characterized in that: It includes a zero-sequence current transformer, a leakage current detection circuit, a time-delay voltage detection circuit, and a tripping drive circuit. The secondary side of the zero-sequence current transformer is connected to the input terminal of the leakage current detection circuit, the output terminal of the leakage current detection circuit is connected to the input terminal of the time-delay voltage detection circuit, and the output terminal of the time-delay voltage detection circuit is connected to the tripping drive circuit. The time-delay voltage detection circuit has a time-delay threshold. When the electrical signal induced by the zero-sequence current transformer meets the leakage current threshold of the leakage current detection circuit, the leakage current detection circuit sends a signal to the time-delay voltage detection circuit. After the time-delay voltage detection circuit passes the time-delay threshold, it activates the tripping drive circuit.

2. The time-delay leakage current protection device according to claim 1, characterized in that: The delayed voltage detection circuit includes a voltage detector U2, which has a built-in delayed threshold. The output of the leakage current detection circuit and one end of the tripping drive circuit are respectively connected to different pins of the voltage detector U2.

3. A time-delay leakage current protector according to claim 1, characterized in that: The The delayed voltage detection circuit includes a voltage detector U2 and a first capacitor, the capacitance of which determines the delay threshold. The output of the leakage current detection circuit, one end of the tripping drive circuit, and the first end of the first capacitor are connected to different pins of the voltage detector U2, and the second end of the first capacitor is grounded.

4. A time-delay leakage current protection device according to claim 3, characterized in that: The number of first capacitors is at least two, and the capacitance value of each first capacitor is different. The capacitance value of the first capacitor determines the delay threshold. The second terminal of all first capacitors is grounded. The delay voltage detection circuit also includes a switching switch SW2. One end of the switching switch SW2 is connected to the pin of the voltage detector U2, and the other end of the switching switch SW2 is connected to the first terminal of any first capacitor. When the switching switch SW2 selects different first capacitors, the corresponding delay threshold is different.

5. A time-delay leakage current protection device according to claim 2 or 3, characterized in that: The delayed voltage detection circuit also includes diode D17, which is connected between the trip drive circuit and the pin of voltage detector U2.

6. A time-delay leakage current protection device according to claim 2 or 3, characterized in that: The delayed voltage detection circuit also includes a capacitor C9, one end of which is grounded, and the other end of which is connected to the pin of the voltage detector U2 and the output of the leakage current detection circuit.

7. A time-delay leakage current protection device according to claim 2 or 3, characterized in that: It also includes a power supply circuit and a step-down circuit; one end of the power supply circuit is connected to the main line, and the other end is connected to the step-down circuit. The other end of the step-down circuit is connected to the leakage current detection circuit. The voltage of the main line is supplied to the leakage current detection circuit after passing through the power supply circuit and the step-down circuit.

8. A time-delay leakage current protector according to claim 7, characterized in that: The tripping drive circuit includes a tripping coil KM, silicon controlled rectifiers Q1 and Q2, a resistor R4, and a diode D14. One end of the tripping coil KM is connected to the power supply circuit, and the other end of the tripping coil KM is connected to the anode of silicon controlled rectifier Q1 and one end of the step-down circuit. The control electrode of silicon controlled rectifier Q1 is connected to one end of resistor R4, and the other end of resistor R4 is connected to the cathode of diode D14. The anode of diode D14 is connected to the other end of the step-down circuit. The cathode of silicon controlled rectifier Q1 is connected to the anode of silicon controlled rectifier Q2, and the control electrode of silicon controlled rectifier Q2 is connected to the output terminal of the delay voltage detection circuit.

9. A time-delay leakage current protector according to claim 1, characterized in that: The leakage current detection circuit includes a leakage current detection chip U1 and a signal conditioning circuit. The signal conditioning circuit is connected between the input pin of the leakage current detection chip and the secondary side of the zero-sequence current transformer. The input terminal of the delay voltage detection circuit is connected to the output pin of the leakage current detection chip.

Images