CN107404106B - Electric leakage simulation test circuit, electric leakage protector and electric leakage protection method - Google Patents
Electric leakage simulation test circuit, electric leakage protector and electric leakage protection method Download PDFInfo
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- CN107404106B CN107404106B CN201710550259.7A CN201710550259A CN107404106B CN 107404106 B CN107404106 B CN 107404106B CN 201710550259 A CN201710550259 A CN 201710550259A CN 107404106 B CN107404106 B CN 107404106B
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- 238000004088 simulation Methods 0.000 title claims abstract description 128
- 238000012360 testing method Methods 0.000 title claims abstract description 105
- 230000001012 protector Effects 0.000 title claims abstract description 46
- 238000000034 method Methods 0.000 title claims abstract description 13
- 230000003044 adaptive effect Effects 0.000 claims abstract description 15
- 238000001514 detection method Methods 0.000 claims description 31
- 230000005611 electricity Effects 0.000 claims description 24
- 238000006243 chemical reaction Methods 0.000 claims description 7
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- 238000010616 electrical installation Methods 0.000 abstract description 5
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/26—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents
- H02H3/32—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors
- H02H3/325—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors involving voltage comparison
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
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Abstract
The invention discloses a leakage simulation test circuit, a leakage protector and a leakage protection method, wherein the circuit comprises: the test circuit comprises a test circuit body (30), a power taking end (31) and a power returning end (32); the power taking end (31) is adaptively connected to a direct-current power supply in the leakage protector to be simulated; the direct current power supply takes a zero line of an alternating current power supply of the electric leakage protector as a reference ground; the test circuit body (30) is connected between the power taking end (31) and the power returning end (32) in an adaptive mode and used for conducting a leakage simulation test on a load of the alternating current power supply; the power return end (32) is connected to the zero line in an adaptive mode, and forms a leakage simulation test loop with the power taking end (31). The scheme of the invention can overcome the defects of large electrical installation space, high cost, poor safety and the like in the prior art, and has the beneficial effects of small electrical installation space, low cost and good safety.
Description
Technical Field
The invention belongs to the technical field of electrical protection, and particularly relates to a leakage simulation test circuit, a leakage protector and a leakage protection method.
Background
The leakage protector, called leakage breaker for short, can effectively prevent electric shock accidents. For example: the leakage protector is mainly used for protecting the electric shock of a person with fatal danger when the equipment has leakage faults, has overload and short-circuit protection functions, can be used for protecting the overload and short circuit of a circuit or a motor, and can also be used as a leakage protector for infrequently switching and starting the circuit under normal conditions.
The leakage simulation test circuit can simulate the leakage situation, so that whether the leakage protector works normally or not is checked, namely whether the action of the leakage protector is reliable or not is checked. Generally, the leakage simulation test circuit is composed of a key and a resistor, one end of the leakage simulation test circuit is connected to a live wire behind a detection circuit of the leakage protector, and the other end of the leakage simulation test circuit crosses the detection circuit of the leakage protector and is connected to a zero wire. Thus, the leakage simulation test circuit is connected to the phase line circuit and is a strong current circuit, and enough electric clearance needs to be ensured; moreover, the resistance and the allowable power of the resistor are relatively large.
In the prior art, the defects of large electrical installation space, high cost, poor safety and the like exist.
Disclosure of Invention
The invention aims to solve the defects, and provides a leakage simulation test circuit, a leakage protector and a leakage protection method, so as to solve the problem that the safety of the leakage simulation test circuit is poor due to the fact that electricity is taken from a phase line in the prior art, and achieve the effect of improving the safety.
The invention provides a leakage simulation test circuit, comprising: the test circuit comprises a test circuit body, a power taking end and a power returning end; the power taking end is adaptively connected to a direct-current power supply in the leakage protector to be simulated; the direct current power supply takes a zero line of an alternating current power supply of the electric leakage protector as a reference ground; the test circuit body is connected between the power taking end and the power returning end in an adaptive mode and used for forming a leakage simulation test loop from the power taking end to the power returning end and carrying out a leakage simulation test on a load of the alternating current power supply; the electricity return end is connected to the zero line in an adaptive mode so as to form an electric leakage simulation test loop with the electricity taking end.
Optionally, the test circuit body includes: a leakage analog switch; the first end of the electric leakage analog switch is connected to the power taking end; and the second end of the leakage analog switch is connected to the power return end.
Optionally, the test circuit body further includes: a leakage simulation resistor; the first end of the leakage analog resistor is connected to the power taking end; the second end of the leakage simulation resistor is in adaptive connection with the first end of the leakage simulation switch; the second end of the leakage analog switch is connected to the power return end; or the first end of the leakage analog switch is connected to the power taking end; the second end of the leakage simulation switch is in adaptive connection with the first end of the leakage simulation resistor; and the second end of the leakage analog resistor is connected to the power return end.
Optionally, the resistance value of the leakage simulation resistor is 0-2400 Ω; and/or the electrifying power of the electric leakage simulation resistor is 0-0.72W.
Optionally, the leakage analog switch includes: at least one of a toggle switch, a rotary switch and an on-off switch.
In accordance with another aspect of the present invention, there is provided a leakage protector, including: the device comprises an alternating current power supply, a master control switch and a leakage detection circuit; further comprising: a leakage simulation test circuit as described above; the alternating current power supply is sequentially connected with the main control switch and the electric leakage detection circuit; the leakage detection circuit is used for detecting leakage of the load of the alternating current power supply; when the load is determined to generate electric leakage, the main control switch is enabled to disconnect the alternating current power supply; and/or the direct current power supply is also used for providing the power taking end of the electric leakage simulation test circuit with the direct current power supply so as to carry out simulation test on the electric leakage detection circuit.
Optionally, the leakage detecting circuit includes: the system comprises a zero sequence transformer, a power supply module and a control module; the zero-sequence transformer is connected with a phase line and a zero line of the alternating current power supply and used for acquiring a current difference between a phase line current and a zero line current of the alternating current power supply so as to perform electric leakage detection on the load; the power supply module is respectively connected with the zero sequence transformer and the control module, is also connected with the phase line and the zero line, and is used for providing the direct-current power supply and the reference ground for the control module; the control module is connected with the main control switch and used for determining whether the current difference is greater than or equal to a set current threshold value; and when the current difference is larger than or equal to the set current threshold, determining that the load has electric leakage, and disconnecting the main control switch to disconnect the connection between the alternating current power supply and the load.
Optionally, the power module includes: provided is a buck conversion circuit.
Optionally, the master switch includes: at least one of a trip unit and a circuit breaker.
In accordance with another aspect of the present invention, there is provided a leakage protection method, including: using the leakage protector to detect leakage of the load of the alternating current power supply; when the load is determined to generate electric leakage, the main control switch is enabled to disconnect the alternating current power supply; and/or providing the direct current power supply to the electricity taking end of the electric leakage simulation test circuit to form an electric leakage simulation test loop from the electricity taking end to the electricity returning end, and carrying out electric leakage simulation test on a load of the alternating current power supply.
Optionally, the detecting of the leakage of the load of the ac power source includes: acquiring a current difference between phase line current and zero line current of the alternating current power supply so as to perform electric leakage detection on the load; determining whether the current difference is greater than or equal to a set current threshold to determine that the load leaks when the current difference is greater than or equal to the set current threshold.
Optionally, the performing a leakage simulation test on the load of the ac power supply includes: when the electric leakage simulation test circuit comprises an electric leakage simulation switch and an electric leakage simulation resistor and the electric leakage detection circuit comprises a zero sequence transformer, if the electric leakage simulation switch is switched on, the current from the electricity taking end to the electricity return end of the electric leakage simulation test circuit does not pass through the zero sequence transformer, so that the phase line current and the zero line current of the alternating current power supply acquired by the zero sequence transformer are unequal; and when the phase line current and the zero line current are not equal, determining that the load of the alternating current power supply leaks electricity.
According to the scheme of the invention, by adopting the leakage simulation circuit (such as the second leakage simulation test circuit 25), the series resistor (such as the second resistor R2) in the leakage simulation circuit allows the resistor with smaller resistance and smaller power to be selected.
Furthermore, according to the scheme of the invention, the electric leakage simulation circuit is a low-voltage circuit, so that the electric clearance can be effectively ensured, the electric safety is ensured, and the structural size is reduced.
Further, according to the scheme of the invention, the electric leakage simulation circuit takes the chip power supply with the zero line as the reference ground and takes electricity from the chip power supply VCC; the resistor with smaller resistance and smaller power can be selected, the electrical clearance is ensured, the electrical safety is ensured, and the structure volume is reduced.
Therefore, according to the scheme provided by the invention, the leakage simulation test circuit obtains electricity from the direct-current power supply VCC of the detection circuit of the leakage protector, and the direct-current power supply VCC takes the zero line as a reference ground, so that the problem of poor electrical safety caused by the fact that the leakage simulation test circuit obtains electricity from the phase line in the prior art is solved, the defects of large electrical installation space, high cost and poor safety in the prior art are overcome, and the beneficial effects of small electrical installation space, low cost and good safety are realized.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.
Drawings
Fig. 1 is a schematic structural diagram of a leakage simulation test circuit according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of an embodiment of the earth leakage protection circuit and the analog earth leakage circuit, wherein a control chip controls a release or a breaker;
FIG. 3 is a schematic diagram of a power supply principle of an embodiment of the first power module in FIG. 2;
fig. 4 is a schematic structural diagram of an embodiment of the earth leakage protector of the present invention;
fig. 5 is a schematic diagram of a power supply principle (i.e., a single diode rectification and BUCK step-down circuit) of an embodiment of the second power module in fig. 4.
The reference numbers in the embodiments of the present invention are as follows, in combination with the accompanying drawings:
10-first master switch (e.g., a trip or circuit breaker, etc.); 11-a first zero sequence transformer; 12-a first power supply module; 121-a rectifier bridge; 122-a voltage conversion circuit; 13-first control module (e.g., control chip, control circuit, etc.); 14-a first electrical load; 15-a first leakage simulation test circuit; 20-a second master switch (e.g., a trip or circuit breaker, etc.); 21-a second zero sequence transformer; 22-a second power supply module; 23-a second control module (e.g. control chip, control circuit, etc.); 24-a second electrical load; 25-a second leakage simulation test circuit; 30-test circuit body; 31-a power taking end; 32-a power return end; 33-leakage analog switch; 34-leakage analog resistance.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the specific embodiments of the present invention and the accompanying drawings. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
According to an embodiment of the present invention, a leakage simulation test circuit is provided, as shown in fig. 1, which is a schematic structural diagram of an embodiment of the circuit of the present invention. The leakage current simulation test circuit may include: the test circuit comprises a test circuit body 30, a power taking end 31 and a power returning end 32.
In an alternative example, the power-taking terminal 31 is adapted to be connected to a dc power supply in the earth leakage protector to be simulated. The direct current power supply takes a zero line of an alternating current power supply of the electric leakage protector as a reference ground.
In an optional example, the power return end 32 is adapted to be connected to the zero line to form a leakage simulation test loop with the power taking end 31.
For example: referring to the example shown in fig. 4, the chip power supply with the zero line as the reference ground, and the leakage simulation circuit for taking power from the chip power supply VCC.
For example: referring to the example shown in fig. 4, the power supply of the second leakage simulation test circuit (e.g., the simulated leakage circuit) 25 draws power from the power supply VCC of the second control module (e.g., the control chip) 23, instead of drawing power from the phase line. Meanwhile, the reference ground corresponding to the power source VCC of the second control module (e.g., control chip) 23 is the zero line.
Therefore, the leakage simulation test circuit gets electricity from the direct current power supply in the leakage protector and returns the electricity to the zero line of the alternating current power supply, and the direct current power supply takes the zero line as a reference ground, so that the electricity can be got from weak current to improve the electricity getting safety; and, make electric leakage simulation test circuit be low-voltage circuit, can effectively guarantee the electric clearance, guarantee electric safety, reduce the structure volume.
In an optional example, the test circuit body 30 is adapted to be connected between the power taking terminal 31 and the power returning terminal 32, and is configured to form a leakage simulation test loop from the power taking terminal 31 to the power returning terminal 32, so as to perform a leakage simulation test on a load of the ac power supply, so as to verify the leakage protector.
Alternatively, the test circuit body 30 may include: a leakage analog switch 33.
In an alternative specific example, a first terminal of the leakage analog switch 33 is connected to the power taking terminal 31; the second terminal of the leakage analog switch 33 is connected to the power return terminal 32.
Optionally, the test circuit body 30 may further include: a leakage simulation resistor 34.
For example: referring to the example shown in fig. 4, the leakage analog switch 33 may be the second button K2, and the leakage analog resistor 34 may be a series resistor (e.g., the second resistor R2).
In an alternative specific example, a first terminal of the leakage analog resistor 34 is connected to the power taking terminal 31; the second end of the leakage analog resistor 34 is in adaptive connection with the first end of the leakage analog switch 33; the second terminal of the leakage analog switch 33 is connected to the power return terminal 32.
In an alternative specific example, a first terminal of the leakage analog switch 33 is connected to the power taking terminal 31; the second end of the leakage analog switch 33 is in adaptive connection with the first end of the leakage analog resistor 34; the second terminal of the leakage analog resistor 34 is connected to the feedback terminal 32.
Therefore, the electric leakage simulation test is convenient and reliable and has a simple structure through the adaptation setting of the electric leakage simulation switch and even the adaptation setting of the electric leakage simulation switch and the electric leakage simulation resistor.
In an optional example, the resistance value of the leakage simulation resistor 34 is 0-2400 Ω; and/or the electrifying power of the leakage simulation resistor 34 is 0-0.72W.
Optionally, the resistance of the resistor is related to the voltage of the power taking terminal. The higher the voltage of the power-taking terminal is, the larger the resistance value of the resistor is, and the higher the power-on power range is. If the highest voltage is 24V, the resistance value range of the resistor is 0-2400 ohm, and the power-on power is 0-0.72W.
In an optional specific example, the voltage of the power-taking end to the power-returning end is 3.3V, the resistance value of the resistor is 330-110 ohms to ensure that the leakage current is 10-30 mA, and the power-on power range is 0.033-0.099W.
In an optional specific example, the voltage of the power-taking end to the power-returning end is 5V, in order to ensure that the leakage current is 10 mA-30 mA, the resistance value of the resistor is 500 ohm-166.67 ohm, and the power-on power range is 0.05W-0.15W.
Preferably, the power taking end is common in 3.3V or 5V, so that the resistance range of the resistor is 110-500 ohm, and the allowable power range of the resistor is 0.03-0.2W.
For example: the series resistor (for example, the second resistor R2) allows the resistor with smaller resistance and power to be selected, and simultaneously, the electric gap is ensured, the electric safety is ensured, and the structure volume is reduced.
For example: since VCC is low relative to the voltage of zero, the resistance and allowed power required for the second resistor R2 is much less than that of fig. 2. For example: VCC is 5V (zero line is reference ground), and in order to ensure that the test leakage current is 30mA, the resistance value of the second resistor R2 is 166.7 ohms, and the electrified power is 0.15W. Meanwhile, the VCC voltage is low, the electric clearance can be reduced, the electric safety is ensured, and the structure volume is reduced.
Therefore, the electric leakage simulation resistor can be used for allowing the resistor with smaller resistance and smaller power to be selected by taking electricity from the direct-current power supply, so that the cost is reduced, and the test safety is improved.
In an alternative example, the leakage current simulation switch 33 may include: at least one of a toggle switch, a rotary switch and an on-off switch.
For example: toggle switch, knob switch, on-off switch all can. Control valves, relays, transistors, thyristors, etc. are theoretically possible, but the cost is much higher due to the need to add peripheral control circuitry.
Therefore, the convenience and flexibility of the operation in the electric leakage mode can be improved through the electric leakage analog switches in various forms.
Through a large number of tests, it is verified that by using the technical solution of the present embodiment, through using the leakage simulation circuit (for example, the second leakage simulation test circuit 25), the series resistor (for example, the second resistor R2) in the leakage simulation circuit allows selecting a resistor with a smaller resistance and a smaller power.
According to the embodiment of the invention, the leakage protector corresponding to the leakage simulation test circuit is also provided. Referring to fig. 4, a schematic structural view of an embodiment of the protector of the present invention is shown. The earth leakage protector may include: an alternating current power supply, a main control switch (for example: a second main control switch 20 shown in fig. 4) and a leakage detection circuit; the method can also comprise the following steps: the leakage current simulation test circuit described above (for example, the second leakage current simulation test circuit 25 shown in fig. 4).
In an optional example, the ac power supply, which is in turn connected to the main switch and the leakage detection circuit, may be configured to supply power to a load.
Optionally, the master switch may include: at least one of a trip unit and a circuit breaker.
Therefore, the reliability and convenience of controlling the alternating current power supply can be improved through the master control switch in various forms.
In an optional example, the leakage detection circuit may be configured to perform leakage detection on a load of the ac power supply; when the load is determined to generate electric leakage, the main control switch is enabled to disconnect the alternating current power supply so as to perform electric leakage protection on the load; and/or, the leakage detection circuit can be further configured to provide the direct-current power supply to the power taking terminal 31 of the leakage simulation test circuit, so as to perform a simulation test on the leakage detection circuit.
Therefore, the reliability and the safety of the leakage protection can be improved through the adaptive arrangement of the alternating-current power supply, the master control switch, the leakage detection circuit and the leakage simulation test circuit.
Alternatively, the leakage detecting circuit may include: a zero sequence transformer (e.g., the second zero sequence transformer 21 shown in fig. 4), a power module (e.g., the second power module 22 shown in fig. 4), and a control module (e.g., the second control module 23 shown in fig. 4).
In an optional specific example, the zero sequence transformer, connected to the phase line and the zero line of the ac power supply, may be configured to obtain a current difference between a phase line current and a zero line current of the ac power supply, so as to perform leakage detection on the load.
In an optional specific example, the power module is connected to the zero sequence transformer and the control module, and is further connected to the phase line and the zero line, and may be configured to provide the direct-current power and the reference ground to the control module.
More optionally, the power module may include: provided is a buck conversion circuit.
Therefore, the direct-current power supply output by the power supply module is more flexible and diversified through the voltage-reducing conversion circuit, and the application range of the direct-current power supply is widened.
In an optional specific example, the control module, connected to the main control switch, may be configured to determine whether the current difference is greater than or equal to a set current threshold; and when the current difference is larger than or equal to the set current threshold, determining that the load has electric leakage, and disconnecting the main control switch to disconnect the connection between the alternating current power supply and the load.
Therefore, the accuracy and the reliability of leakage protection detection can be improved through the adaptive setting of the zero sequence transformer, the power supply module and the control module.
In one embodiment, fig. 2 may show the leakage protection principle with a leakage simulation test circuit. In fig. 2, the earth leakage protector may include: the device comprises a first main control switch 10, a first zero sequence transformer 11, a first power module 12, a first control module 13, a first electrical appliance load 14 and a first electric leakage simulation test circuit 15 which are matched and arranged.
In fig. 2, a first power module 12 converts ac power of the phase line and the neutral line into dc VCC and GND, and supplies power to a first control module (e.g., a control chip module) 13, and the circuit principle is as shown in fig. 3.
In fig. 3, where VCC is a dc voltage, typically 3.3V or 5V, the reference ground is dc ground GND. The first power module 12 may further include: the rectifier bridge 121, the first capacitor C1 and the voltage conversion circuit 122 are arranged in a matching mode.
Referring to the examples shown in fig. 2 and 3, the leakage protection principle of the leakage protector is as follows: detecting the current difference between the phase line and the zero line by a first zero sequence transformer 11
At normal time
. When in use
When the current is greater than or equal to a certain set value (the set value is generally between 15mA and 30 mA), protection occurs, and the power supply is disconnected (for example, the first main control switch 10 is disconnected, and the first main control switch 10 may include a release or a circuit breaker, etc.).
Referring to the example shown in fig. 2 and 3, the first leakage simulation test circuit (e.g., leakage simulation circuit) 15 may include: a first key K1 and a first resistor R1. When the first key K1 is pressed, the phase line has current
Flows through a first resistor R1 into the neutral line,
does not pass through the first zero sequence transformer 11, resulting in
Not 0, so that a protection switch-off occurs.
The experiment proves that the leakage simulation circuit shown in fig. 2 at least comprises two defects: (1) the first key K1 and the first resistor R1 are located on a phase line, are strong current circuits, and need to ensure sufficient electrical clearance; (2) the resistance and allowable power requirement of the first resistor R1 is relatively large. For example, at 220VAC, in order to ensure that the test leakage current is 30mA, the resistance value of the resistor is 7333 ohms, and the power-on running power is 6.6W.
In an alternative embodiment, referring to the example shown in fig. 4, the earth-leakage protector may include: the second main control switch 20, the second zero sequence transformer 21, the second power module 22, the second control module 23, the second electrical load 24 and the second leakage simulation test circuit 25 are adapted to each other.
In an alternative example, the second leakage simulation test circuit 25 may include: a second key K2 (such as a leakage simulation key) and a second resistor R2 (such as a leakage simulation resistor) are arranged in a matching way. The differences from fig. 2 are: the power supply of the second leakage simulation test circuit (e.g., the simulated leakage circuit) 25 takes power from the power supply VCC of the second control module (e.g., the control chip) 23, instead of taking power from the phase line. Meanwhile, the reference ground corresponding to the power source VCC of the second control module (e.g., control chip) 23 is the zero line.
Wherein the second resistor R2 requires a much smaller resistance and allowed power than in fig. 2, since VCC is lower than the voltage of the neutral line. For example: VCC is 5V (zero line is reference ground), and in order to ensure that the test leakage current is 30mA, the resistance value of the second resistor R2 is 166.7 ohms, and the electrified power is 0.15W. Meanwhile, the VCC voltage is low, the electric clearance can be reduced, the electric safety is ensured, and the structure volume is reduced.
For example: in the leakage protection circuit shown in fig. 4, the current difference between the phase line and the zero line is detected by the second zero-sequence transformer 21
At normal time
. When in use
When the current is greater than or equal to a certain set value (the set value is generally between 15mA and 30 mA), the signal output by the second zero sequence transformer 21 to the second control module (for example, the main chip) 23 changes, and the second control module (for example, the main chip) 23 sends out protectionThe signal opens the second master switch 20 (e.g., a circuit breaker or a trip unit) to disconnect the power supply to the load (e.g., the second electrical load 24).
For example: the earth leakage protectors shown in fig. 4 are all provided with an earth leakage simulation test circuit for checking whether the earth leakage protector operates reliably. Principle of electric leakage simulation: when the leakage simulation button (for example, the second button K2) is pressed, a part of the current of the phase line does not flow into the zero line through the second zero sequence transformer 21, resulting in a current difference through the second zero sequence transformer 21
And is not 0, so that the second control module (e.g., the master chip) 23 determines that earth leakage protection is occurring and disconnects the power supply.
In an alternative example, the power circuit (i.e., the second power module 22) in fig. 4 using the zero line as the reference ground may be implemented in various ways, and fig. 5 is a BUCK step-down circuit (i.e., a step-down converter circuit) for controlling the voltage drop of the voltage VCC by controlling the on/off of G1 (e.g., the switch tube G1), the circuit using the zero line as the reference ground.
The BUCK voltage reducing circuit shown in fig. 5 may further include: the diode D1, the second diode D2, the inductor L1, the second capacitor C2 and the third capacitor C3 are arranged in a matched mode. The second diode D2 and the third capacitor C3 form a single diode rectifier circuit. The second diode D2 can only conduct in one direction, only the positive half wave of the alternating current of the phase line can pass through the D2, and the C3 can filter the energy stored in the passed positive half wave of the alternating current to form a direct current power supply relative to the zero line. G1 is a controllable switch tube, when G1 is controlled to be switched on, a D2 and C3 rectified direct current power supply supplies power to a load through an inductor L1, meanwhile, an inductor L1 stores a part of energy, then G1 is controlled to be switched off, and the load is supplied with power only through an inductor L1. Such periodic operation allows for regulation of the output voltage by adjusting the relative time that G1 is turned on and off.
For example: the BUCK circuit can be a single-tube non-isolated conversion circuit with output voltage smaller than input voltage.
Since the processing and functions implemented by the protector of this embodiment substantially correspond to the embodiment, principle and example of the circuit shown in fig. 1, the description of this embodiment is not given in detail, and reference may be made to the related description in the foregoing embodiment, which is not described herein again.
Through a large number of tests, the technical scheme of the invention can effectively ensure the electric clearance, ensure the electric safety and reduce the structural volume by making the electric leakage simulation circuit a low-voltage circuit.
According to the embodiment of the invention, a leakage protection method corresponding to the leakage protector is also provided. The leakage protection method may include: using the leakage protector to detect leakage of the load of the alternating current power supply; and when the load is determined to have electric leakage, the main control switch is enabled to disconnect the alternating current power supply.
In an alternative specific example, the detecting of the leakage of the load of the ac power supply may include: acquiring a current difference between phase line current and zero line current of the alternating current power supply so as to perform electric leakage detection on the load; and determining whether the current difference is greater than or equal to a set current threshold value, and when the current difference is greater than or equal to the set current threshold value, determining that the load has electric leakage, and disconnecting the main control switch to disconnect the connection between the alternating current power supply and the load.
For example: in the leakage protection circuit shown in fig. 4, the current difference between the phase line and the zero line is detected by the second zero-sequence transformer 21
At normal time
. When in use
When the current is greater than or equal to a certain set value (the set value is generally between 15mA and 30 mA), the signal output by the second zero sequence transformer 21 to the second control module (for example, the main chip) 23 changes, the second control module (for example, the main chip) 23 sends out a protection signal, and the third control module is disconnectedA two-master switch 20 (e.g., a circuit breaker or a trip unit) disconnects the power supply to a load (e.g., a second electrical load 24).
Therefore, the accuracy and the reliability of leakage protection detection can be improved through the adaptive setting of the zero sequence transformer, the power supply module and the control module.
Optionally, the direct-current power supply may be provided to the power taking terminal 31 of the leakage simulation test circuit to form a leakage simulation test loop from the power taking terminal 31 to the power returning terminal 32, and a leakage simulation test may be performed on a load of the alternating-current power supply to verify the leakage protector.
Therefore, the reliability and the safety of the leakage protection can be improved through the adaptive arrangement of the alternating-current power supply, the master control switch, the leakage detection circuit and the leakage simulation test circuit.
In an alternative specific example, performing an analog test on the leakage detecting circuit may include: when the leakage simulation test circuit may include the leakage simulation switch 33 and the leakage simulation resistor 34, and the leakage detection circuit may include a zero sequence transformer, if the leakage simulation switch 33 is turned on, the current from the power taking end 31 to the power returning end 32 of the leakage simulation test circuit does not pass through the zero sequence transformer, so that the phase line current and the zero line current of the ac power source obtained by the zero sequence transformer are not equal; and when the phase line current and the zero line current are not equal, determining that the load of the alternating current power supply leaks electricity.
For example: the earth leakage protectors shown in fig. 4 are all provided with an earth leakage simulation test circuit for checking whether the earth leakage protector operates reliably. Principle of electric leakage simulation: when the leakage simulation button (for example, the second button K2) is pressed, a part of the current of the phase line does not flow into the zero line through the second zero sequence transformer 21, resulting in a current difference through the second zero sequence transformer 21
And is not 0, so that the second control module (e.g., the master chip) 23 determines that earth leakage protection is occurring and disconnects the power supply.
Therefore, the leakage simulation test circuit which obtains electricity from the direct-current power supply has good electricity-obtaining safety, so that the leakage simulation test has good convenience and high reliability.
Since the processing and functions implemented by the method of the present embodiment substantially correspond to the embodiments, principles and examples of the protector shown in fig. 2 to fig. 5, the description of the present embodiment is not detailed, and reference may be made to the related descriptions in the foregoing embodiments, which are not described herein again.
Through a large number of tests, the technical scheme of the invention is adopted, and the leakage simulation circuit takes electricity from the chip power supply VCC through the chip power supply which takes the zero line as the reference ground; the resistor with smaller resistance and smaller power can be selected, the electrical clearance is ensured, the electrical safety is ensured, and the structure volume is reduced.
In summary, it is readily understood by those skilled in the art that the advantageous modes described above can be freely combined and superimposed without conflict.
The above description is only an example of the present invention, and is not intended to limit the present invention, and it is obvious to those skilled in the art that various modifications and variations can be made in the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.
Claims (10)
1. A leakage current simulation test circuit, comprising: the test circuit comprises a test circuit body (30), a power taking end (31) and a power returning end (32); wherein,
the power taking end (31) is adaptively connected to a direct-current power supply in the leakage protector to be simulated; the direct current power supply takes a zero line of an alternating current power supply of the electric leakage protector as a reference ground;
the test circuit body (30) is connected between the power taking end (31) and the power returning end (32) in an adaptive mode, and is used for forming a leakage simulation test loop from the power taking end (31) to the power returning end (32) and carrying out a leakage simulation test on a load of the alternating current power supply; the test circuit body (30) comprises: a leakage simulation switch (33) and a leakage simulation resistor (34);
the power return end (32) is adaptively connected to the zero line so as to form a leakage simulation test loop with the power taking end (31);
wherein,
the first end of the leakage simulation resistor (34) is connected to the power taking end (31);
the second end of the leakage simulation resistor (34) is in adaptive connection with the first end of the leakage simulation switch (33);
the second end of the leakage analog switch (33) is connected to the power return end (32);
or,
a first end of the leakage analog switch (33) is connected to the power taking end (31);
the second end of the leakage analog switch (33) is in adaptive connection with the first end of the leakage analog resistor (34);
the second end of the leakage analog resistor (34) is connected to the power return end (32).
2. The leakage current simulation test circuit according to claim 1, wherein the resistance value of the leakage current simulation resistor (34) is 0-2400 Ω; and/or the electrifying power of the leakage simulation resistor (34) is 0-0.72W.
3. A leakage simulation test circuit according to claim 1 or 2, wherein the leakage simulation switch (33) comprises: at least one of a toggle switch, a rotary switch and an on-off switch.
4. A earth-leakage protector, comprising: the device comprises an alternating current power supply, a master control switch and a leakage detection circuit;
further comprising: a leakage simulation test circuit according to any one of claims 1 to 3;
wherein,
the alternating current power supply is sequentially connected with the main control switch and the electric leakage detection circuit;
the leakage detection circuit is used for detecting leakage of the load of the alternating current power supply; when the load is determined to generate electric leakage, the main control switch is enabled to disconnect the alternating current power supply; and/or the presence of a gas in the gas,
the power taking end (31) is used for providing the direct current power supply for the electric leakage simulation test circuit so as to carry out simulation test on the electric leakage detection circuit.
5. A leakage protector according to claim 4, wherein the leakage detection circuit comprises: the system comprises a zero sequence transformer, a power supply module and a control module; wherein,
the zero sequence transformer is connected with a phase line and a zero line of the alternating current power supply and is used for acquiring a current difference between a phase line current and a zero line current of the alternating current power supply so as to perform electric leakage detection on the load;
the power supply module is respectively connected with the zero sequence transformer and the control module, is also connected with the phase line and the zero line, and is used for providing the direct-current power supply and the reference ground for the control module;
the control module is connected with the main control switch and used for determining whether the current difference is greater than or equal to a set current threshold value; and when the current difference is larger than or equal to the set current threshold, determining that the load has electric leakage, and disconnecting the main control switch to disconnect the connection between the alternating current power supply and the load.
6. A earth-leakage protector according to claim 5, characterized in that the power supply module comprises: provided is a buck conversion circuit.
7. A leakage protector according to any of claims 4-6, wherein the main switch comprises: at least one of a trip unit and a circuit breaker.
8. A method of earth leakage protection, comprising:
using the earth-leakage protector of any one of claims 4-7, detecting an earth leakage of a load of the ac power source;
when the load is determined to generate electric leakage, the main control switch is enabled to disconnect the alternating current power supply;
and/or the presence of a gas in the gas,
and providing the direct current power supply to the electricity taking end (31) of the electric leakage simulation test circuit to form an electric leakage simulation test loop from the electricity taking end (31) to the electricity returning end (32), and carrying out electric leakage simulation test on the load of the alternating current power supply.
9. A leakage protection method according to claim 8, wherein the detecting of the leakage of the load of the ac power supply includes:
acquiring a current difference between phase line current and zero line current of the alternating current power supply so as to perform electric leakage detection on the load;
determining whether the current difference is greater than or equal to a set current threshold to determine that the load leaks when the current difference is greater than or equal to the set current threshold.
10. A leakage protection method according to claim 8 or 9, wherein the performing a leakage simulation test on the load of the ac power supply comprises:
when the electric leakage simulation test circuit comprises an electric leakage simulation switch (33) and an electric leakage simulation resistor (34), and the electric leakage detection circuit comprises a zero sequence transformer, if the electric leakage simulation switch (33) is switched on, the current from a power taking end (31) to a power returning end (32) of the electric leakage simulation test circuit does not pass through the zero sequence transformer, so that the phase line current and the zero line current of the alternating current power supply acquired by the zero sequence transformer are not equal;
and when the phase line current and the zero line current are not equal, determining that the load of the alternating current power supply leaks electricity.
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| CN111293669B (en) * | 2018-12-07 | 2022-06-21 | 格述电子技术(上海)有限公司 | Novel low-power-consumption leakage protector |
| CN112736836A (en) * | 2020-12-11 | 2021-04-30 | 珠海格力电器股份有限公司 | Fireproof control device and method for electrical equipment and electrical equipment |
| CN114002536A (en) * | 2021-11-25 | 2022-02-01 | 格力电器（郑州）有限公司 | PRCD detection device and detection method thereof |
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