Power equipment isolation protection circuit

Abstract

The utility model discloses a power equipment isolation protection circuit, which comprises an isolation transformer T2, a rectifier BR1, an electrolytic capacitor C1, a relay J1, a diode D19, a triode Q17, a resistor R4, a composite thermistor RT1, a composite thermistor RT2, a capacitor C2, a resistor R3, a key switch K1, an optocoupler UT3, a diode D1, an N1 terminal and an L1 terminal, and the N1 terminal and the L1 terminal are used for connecting power equipment. When the live wire or the zero wire of the power equipment is disconnected, the relay J1 trips, the L1 and the N1 are directly disconnected, power supply of the rear-end power equipment is stopped, and the safety of workers is protected. When rear-end power equipment is short-circuited or the power equipment is abnormal and overlarge in current, and the current exceeds the working current I1 of the composite thermistor RT1, the composite thermistor RT1 works to enter a high-resistance state, and at the moment, the composite thermistor RT1 bears most of voltage, so that the circuit does not output L1 and N1 and does not supply power to the power equipment, and the power equipment is protected. And the isolation transformer and rear-end power equipment are directly protected.

Description

Technical Field

[0001] The utility model specifically relates to an isolation protection circuit for electric power equipment. Background Art

[0002] At present, when staff debug and develop AC-powered power equipment, they generally use isolation transformers to power the power equipment. This solution isolates the power supply of power equipment from the AC mains, mainly to protect personnel safety, power equipment safety, and other PC-side safety. However, there is also a problem with directly using isolation transformers to power power equipment. When the isolation transformer is not turned off or the back-end power equipment is abnormally short-circuited or open-circuited, it will not be possible to cut off the power in time to protect the back-end equipment and personnel. Utility Model Content

[0003] The utility model provides an isolation protection circuit for electric equipment to solve the above-mentioned technical problems, and specifically adopts the following technical solutions:

[0004] An isolation protection circuit for electric equipment, comprising: an isolation transformer T2, a rectifier BR1, an electrolytic capacitor C1, a relay J1, a diode D19, a transistor Q17, a resistor R4, a composite thermistor RT1, a composite thermistor RT2, a capacitor C2, a resistor R3, a key switch K1, an optical coupler UT3, a diode D1, an N1 terminal and an L1 terminal, wherein the N1 terminal and the L1 terminal are used to connect the electric equipment;

[0005] One side of the isolation transformer T2 is connected to the L line and the N line of the 220V AC power supply, the other side of the isolation transformer T2 is connected to one side of the rectifier BR1, the electrolytic capacitor C1 is connected to the other side of the rectifier BR1, the positive electrode of the electrolytic capacitor C1 is connected to 12V, the negative electrode of the electrolytic capacitor C1 is grounded, and is also connected to the N1 terminal;

[0006] The L line of the 220V AC power supply is grounded, the N line of the 220V AC power supply is connected to the 5th port of the relay J1, the 4th port of the relay J1 is connected to the N1 terminal through the composite thermistor RT1, the 1st port of the relay J1 is connected to the positive electrode of the diode D19 and the collector of the transistor Q17, the 2nd port of the relay J1 is connected to 12V and the negative electrode of the diode D19, the base of the transistor Q17 is connected to the resistor R4, the capacitor C2 and one end of the resistor R3, the emitter of the transistor Q17 is grounded and also connected to the One end of the composite thermistor RT2, the other end of the resistor R4 and the capacitor C2, and the other end of the resistor R3 are connected to port 1 on one side of the key switch K1, the other end of the composite thermistor RT2 is connected to port 2 of the optocoupler UT3, port 3 of the optocoupler UT3 is connected to port 3 of the key switch K1, port 4 of the optocoupler UT3 is connected to port 4 of the key switch K1, port 2 of the key switch K1 is connected to 12V, port 1 of the optocoupler UT3 is connected to the cathode of the diode D1 and the L1 terminal, and the anode of the diode D1 is grounded.

[0007] Furthermore, the power equipment isolation protection circuit further comprises a light emitting diode LED1, a cathode of the light emitting diode LED1 is connected to a cathode of the electrolytic capacitor C1, and an anode of the light emitting diode LED1 is connected to the N1 terminal.

[0008] Furthermore, the power equipment isolation protection circuit further comprises a resistor R1 and a resistor R2, one end of the resistor R1 and the resistor R2 are connected to the positive electrode of the light emitting diode LED1, and the other end of the resistor R1 and the resistor R2 are connected to the N1 terminal.

[0009] Furthermore, the rectifier BR1 is a bridge rectifier.

[0010] Furthermore, the second capacitor C2 is greater than 22 μF.

[0011] The utility model is beneficial in that the power equipment isolation protection circuit provided effectively protects the isolation transformer and the back-end power equipment, and will not burn out the power equipment due to a short circuit or an open circuit of the back-end power equipment. When the back-end power equipment is short-circuited or open-circuited, the power equipment cannot be powered on, avoiding the risk of being burned out.

[0012] The utility model is also beneficial in that it provides an isolation protection circuit for electric equipment. When power on and power off are required multiple times, it is only necessary to connect the connection line between the protection circuit and the electric equipment and press the switch to power on the equipment. At the same time, when power is cut off, it is only necessary to disconnect one of the live wire L1 or the neutral wire N1 to cut off the power. The operation is convenient, safe and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0014] Figure 1 The utility model is a schematic diagram of an isolation protection circuit for electric power equipment. DETAILED DESCRIPTION

[0015] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0016] In the description of this application, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0017] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0018] like Figure 1 The figure shows an isolation protection circuit of an electric power equipment of the present application, comprising: an isolation transformer T2, a rectifier BR1, an electrolytic capacitor C1, a relay J1, a diode D19, a transistor Q17, a resistor R4, a composite thermistor RT1, a composite thermistor RT2, a capacitor C2, a resistor R3, a key switch K1, an optocoupler UT3, a diode D1, an N1 terminal and an L1 terminal, wherein the N1 terminal and the L1 terminal are used to connect the electric power equipment.

[0019] Specifically, one side of the isolation transformer T2 is connected to the L line and the N line of the 220V AC power supply, and the other side of the isolation transformer T2 is connected to one side of the rectifier BR1. In the embodiment of the present application, the rectifier BR1 is a bridge rectifier.

[0020] The electrolytic capacitor C1 is connected to the other side of the rectifier BR1 , the positive electrode of the electrolytic capacitor C1 is connected to 12V, the negative electrode of the electrolytic capacitor C1 is grounded, and is also connected to the N1 terminal at the same time.

[0021] The L line of the 220V AC power supply is grounded, the N line of the 220V AC power supply is connected to the 5th port of the relay J1, the 4th port of the relay J1 is connected to the N1 terminal through the composite thermistor RT1, the 1st port of the relay J1 is connected to the positive electrode of the diode D19 and the collector of the transistor Q17, and the 2nd port of the relay J1 is connected to 12V and the negative electrode of the diode D19. Preferably, the relay J1 is a micro relay.

[0022] The base of transistor Q17 is connected to resistor R4, capacitor C2 and one end of resistor R3, and the emitter of transistor Q17 is grounded and also connected to one end of composite thermistor RT2, resistor R4 and the other end of capacitor C2. In the embodiment of the present application, capacitor C2 is greater than 22 μF.

[0023] The other end of the resistor R3 is connected to port 1 of the push switch K1, the other end of the composite thermistor RT2 is connected to port 2 of the optocoupler UT3, port 3 of the optocoupler UT3 is connected to port 3 of the push switch K1, port 4 of the optocoupler UT3 is connected to port 4 of the push switch K1, port 2 of the push switch K1 is connected to 12V, port 1 of the optocoupler UT3 is connected to the cathode of the diode D1 and the L1 terminal, and the anode of the diode D1 is grounded.

[0024] In the embodiment of the present application, the power equipment isolation protection circuit further includes a light emitting diode LED1, the cathode of the light emitting diode LED1 is connected to the cathode of the electrolytic capacitor C1, and the anode of the light emitting diode LED1 is connected to the N1 terminal. The power equipment isolation protection circuit further includes a resistor R1 and a resistor R2, one end of the resistor R1 and the resistor R2 is connected to the anode of the light emitting diode LED1, and the other end of the resistor R1 and the resistor R2 is connected to the N1 terminal.

[0025] Specifically, when the switch K1 is pressed, the 12V power supply turns on the PN junction of the transistor Q17 BE, and the coils of the 1 and 2 ports of the micro relay J1 are energized, and the micro relay J1 is in the state of connecting pins 4 and 5. At this time, N1-L1 is energized to supply power to the power equipment, and the light-emitting diode LED1 lights up.

[0026] When the power equipment is powered on and starts working, the N1-L1 path forms a loop and there is a conduction current. At this time, the optocoupler UT3 is turned on, the transistor Q17 remains in the on state, and the micro relay J1 remains in the on state to supply power to the power equipment.

[0027] When the power equipment is open circuit or the live wire L1 (neutral wire N1) has poor contact, N1-L1 is open circuit and the optocoupler UT3 cannot be turned on. As a result, the 12V cannot supply power to the transistor Q17, and the transistor Q17 is cut off and does not work. At this time, the 12V power supply cannot supply power to the coil of the micro relay J1. The micro relay J1 trips and is in the 3-5 pin connection state. N and N1 are disconnected, and the back-end equipment cannot be powered. The light-emitting diode LED1 goes out, which plays a role in protecting the safety of the power equipment and the staff.

[0028] When the power equipment is short-circuited, the load current is too large. At this time, the composite thermistor RT1 enters a high-resistance state. At this time, the AC completes the voltage drop in the composite thermistor RT1, resulting in a very low voltage at the output end (N1 terminal and L1 terminal), protecting the safety of the power equipment.

[0029] At the same time, when the R&D personnel forget to disconnect the front-end switch and do not add the back-end power equipment, the developer may accidentally touch the N1 and L1 lines at the same time. Without a protective device, it will cause a serious electric shock accident. However, after using the protection circuit of this application, when there is no back-end power equipment load, N1 and L1 will not be energized, which further effectively protects personal safety.

[0030] The above shows and describes the basic principle, main features and advantages of the utility model. Those skilled in the art should understand that the above embodiments do not limit the utility model in any form, and any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the utility model.

Claims

1. An isolation protection circuit for electric power equipment, characterized in that: It includes: an isolation transformer T2, a rectifier BR1, an electrolytic capacitor C1, a relay J1, a diode D19, a transistor Q17, a composite thermistor RT1, a composite thermistor RT2, a capacitor C2, a resistor R3, a resistor R4, a key switch K1, an optical coupler UT3, a diode D1, an N1 terminal and an L1 terminal, wherein the N1 terminal and the L1 terminal are used to connect power equipment; One side of the isolation transformer T2 is connected to the L line and the N line of the 220V AC power supply, the other side of the isolation transformer T2 is connected to one side of the rectifier BR1, the electrolytic capacitor C1 is connected to the other side of the rectifier BR1, the positive electrode of the electrolytic capacitor C1 is connected to 12V, the negative electrode of the electrolytic capacitor C1 is grounded, and is also connected to the N1 terminal; The L line of the 220V AC power supply is grounded, the N line of the 220V AC power supply is connected to the 5th port of the relay J1, the 4th port of the relay J1 is connected to the N1 terminal through the composite thermistor RT1, the 1st port of the relay J1 is connected to the positive electrode of the diode D19 and the collector of the transistor Q17, the 2nd port of the relay J1 is connected to 12V and the negative electrode of the diode D19, the base of the transistor Q17 is connected to the resistor R4, the capacitor C2 is connected to one end of the resistor R3, the emitter of the transistor Q17 is grounded and also connected to One end of the composite thermistor RT2, the other ends of the resistor R4 and the capacitor C2, and the other end of the resistor R3 are connected to port 1 of the key switch K1, the other end of the composite thermistor RT2 is connected to port 2 of the optocoupler UT3, port 3 of the optocoupler UT3 is connected to port 3 of the key switch K1, port 4 of the optocoupler UT3 is connected to port 4 of the key switch K1, port 2 of the key switch K1 is connected to 12V, port 1 of the optocoupler UT3 is connected to the cathode of the diode D1 and the L1 terminal, and the anode of the diode D1 is grounded.

2. The power equipment isolation protection circuit according to claim 1, characterized in that: The power equipment isolation protection circuit further comprises a light emitting diode LED1, a cathode of the light emitting diode LED1 is connected to the cathode of the electrolytic capacitor C1, and an anode of the light emitting diode LED1 is connected to the N1 terminal.

3. The power equipment isolation protection circuit according to claim 2, characterized in that: The power equipment isolation protection circuit further comprises a resistor R1 and a resistor R2, one end of the resistor R1 and the resistor R2 are connected to the positive electrode of the light emitting diode LED1, and the other end of the resistor R1 and the resistor R2 are connected to the N1 terminal.

4. The power equipment isolation protection circuit according to claim 1, characterized in that: The rectifier BR1 is a bridge rectifier.

5. The power equipment isolation protection circuit according to claim 1, characterized in that: The capacitor C2 is greater than 22 μF.

6. The power equipment isolation protection circuit according to claim 1, characterized in that: The relay J1 is a micro relay.

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