CN117590161A - Electrical device and method for measuring the insulation state of a load on a plurality of sockets - Google Patents
Electrical device and method for measuring the insulation state of a load on a plurality of sockets Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
- G01R1/30—Structural combination of electric measuring instruments with basic electronic circuits, e.g. with amplifier
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/20—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/145—Indicating the presence of current or voltage
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
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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
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
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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
- G01R31/52—Testing for short-circuits, leakage current or ground faults
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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
- G01R31/56—Testing of electric apparatus
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- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
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Abstract
The invention discloses an electrical device and a method for diagnosing the ground insulation state of a load connected to each socket by socket when a plurality of sockets are connected to a grounded power supply, thereby rapidly coping with electric shock or fire hazard caused by ground insulation damage. The electrical device of the present invention may be provided between the socket and the load alone, or may be manufactured integrally with the socket.
Description
Technical Field
The present invention relates to an electrical device and a method thereof for diagnosing an earth-insulated state of a load connected to a plurality of sockets branched from an earth-insulated power supply independently for each socket and protecting from electric shock and fire by a warning lamp when an abnormal state occurs, and more particularly, to an electrical device and a method for measuring an insulated state of a load on a plurality of sockets branched from an earth-insulated power supply.
In particular, it is an object of the present invention to provide a socket which can take measures quickly because the insulation state of a specific socket load among a plurality of sockets is judged and notified.
Background
The power supply device is a device that supplies power to a predetermined electric device or equipment.
In korea, the power supply provided by korea power company is generally a three-phase four-wire system, and generally the voltage between the final line is 380V and the voltage between the line and the neutral line is 220V, and for a general household using 220V, the line and the neutral line of one of three phases are used, and at this time, the neutral line is made to have the same potential as the general ground.
The electric device is grounded for safety, and the device is protected when electric leakage occurs, so that the danger possibly occurring due to the electric leakage is eliminated.
Further, various techniques are being studied for preventing electric shock or fire possibly occurring in a conventional power supply device due to the above-described leakage or problems occurring in the power supply system, and as examples thereof, refer to patent documents 1 to 4.
Patent document 1 proposes an electric device that detects and notifies an electric shock or fire caused by electric leakage when an insulated electric device fails by detecting an input power supply supplied to an insulated load, wherein the electric device includes, in series with each input power supply, first and second selection switches: a first distribution resistor and a second distribution resistor; a first and a second insulating amplifier for measuring voltages distributed from the first and the second distribution resistors; a first comparator and a second comparator for comparing the voltages detected by the first and second insulating amplifiers with the standard voltage generator, respectively; a cost-effective device for cost-effective of the results of the first comparator and the second comparator; and an output switch outputting the result of the cost-effectiveness unit.
Patent document 2 proposes a leakage detection circuit of a power supply device having a battery cell constituted by a plurality of batteries, the leakage detection circuit comprising: a first current path connected to the positive electrode of the battery cell and having a reference point for generating a reference voltage due to a potential difference between the positive electrode and the negative electrode; the second current path is connected with the positive electrode of the battery unit and is provided with 3 points with different potentials, and the middle point is grounded through an insulation resistor in the 3 points; first and second comparators applying a voltage from each of 2 points, which are spaced apart from a midpoint of the second current path, to one side input terminal, and applying a reference voltage from a reference point of the first current path to the other side input terminal; and a detection circuit that detects whether or not leakage occurs based on outputs of the first comparator and the second comparator.
Patent document 3 proposes an electric leakage cut-off system including: the first judging device comprises an input port connected with the output end of the first video converter, an output port connected with the input end of the first circuit breaker, a first local area network port and a second local area network port; the second judging device is connected with an input port of the output end of the second video converter, an output port of the input end of the second circuit breaker, a first local area network port and a second local area network port; and the main unit is connected with the first local area network port of the first judging device through any local area network cable, the second local area network port of the first judging device is connected with the first local area network port of the second judging device through different local area network cables, the first judging device and the second judging device respectively analyze signals input through the input ports, when electric leakage is judged, a cutting-off signal is output through the output port, and the main unit monitors the states of the first judging device and the second judging device.
Patent document 4 discloses one or more fault detectors each including one end electrically connected to at least one of two or more power lines insulated from a ground and a first neutral point of a potential between voltages of the two or more power lines, and the other end electrically connected to the ground, each fault detector including a current detection portion that limits a leakage current flowing through the ground to a predetermined dangerous current or less and detects the leakage current, the fault detector electrically connected to the power lines being configured such that a current flowing through the fault detector flows in any one of directions in which the current is left or flows from the ground among the one or more fault detectors, and including a unidirectional current portion that unidirectional limits a current path so as to cut off a current flowing through the fault detector in a normal state, the fault detector being a device for preventing electric shock and fire by forming a current path for the leakage current flowing through the two or more power lines or to the ground in the first neutral point.
As described above, most electric shock accidents and fire accidents are phenomena occurring between the earth and the power supply, and in order to prevent such phenomena, a method of separating the power supply from the earth to supply power is adopted.
However, in this case, even if the power supply is insulated from the ground, if the insulation strength between the power supply and the ground is lowered, there is the same phenomenon that there is a risk of fire or electric shock due to leakage current.
Further, patent document 1 has the following problems: when a plurality of sockets are commonly grounded to an insulated power supply, it is not easy to specify a socket of a load having an insulation problem, and it is necessary to check the entire load.
On the other hand, in the electric device, there is an electric device whose neutral line cannot be connected to the ground due to insulation, safety, or the like, and for this purpose, an electrically isolated (Galvanic Isolation) power supply device is provided between the power supply system and the electric device.
Such an insulated electrical apparatus constitutes an inter-floor ground terminal that is separated from a power line supplied from a power supply device and from which the ground terminal floats, and is capable of preventing electric shock and fire caused by electric leakage due to life, deterioration, or flooding of the device, but there is no technique for preventing these.
In particular, the floating ground and the power supply line cannot be monitored, and thus there is a problem in that the insulating state of the electrical device cannot be grasped.
Prior art literature
Patent literature
Patent document 1: korean patent No. 10-2386390
Patent document 2: korean laid-open patent No. 10-2003-0010582
Patent document 3: korean laid-open patent No. 10-2019-012444
Patent document 4: korean patent No. 10-2169232.
Disclosure of Invention
Problems to be solved by the invention
The present invention has been made to solve the above-described problems of the prior art, and an object thereof is to provide an electrical apparatus and a method for measuring an insulation state of a load on a plurality of sockets of a power supply branch of ground insulation, so that when a plurality of sockets are connected to a ground power supply, the ground insulation state of the load connected to each socket is diagnosed for each socket, and thus, a danger of an electric shock or fire due to ground insulation damage can be rapidly dealt with.
In contrast, if an individual socket can grasp the insulation state of the load connected to each socket, it is easy to find a fault position and shorten a modification time, and thus there is an effect that costs and financial resources can be reduced.
Solution for solving the technical problems
In an electrical apparatus for measuring an insulation state of a load on a plurality of sockets of a power supply branch of ground insulation of the present invention for solving the object as described above, there is included an individual leakage measuring apparatus 400, the individual leakage measuring apparatus 400 including: a current measuring device 420 for measuring a current difference flowing through two power lines using a core, or ferrite, or a current withstand test method; voltage measuring means 430 for measuring voltages at various places; check switches 431, 434 for alternately operating the respective voltage measuring devices, each voltage measuring device having an operating time of one cycle or more; an isolation amplifier 433, 436 for measuring the voltage at the measuring resistor 432, 435; an operational amplifier 421 directly connected to the current measuring device 420, for converting the current into a voltage, and outputting the voltage to the microprocessor 450 for judging the ground insulation state of the load; the microprocessor 450 is configured to perform analog-digital converter conversion on the outputs of the operational amplifier 421 and the isolation amplifiers 433 and 436, and determine a ground isolation state of the connected load through internal calculation; and a display processing unit 460 for notifying the outside of the displayAnd (5) judging the insulation state. Wherein in the microprocessor 450, the converted measured voltage value 451 and the reference signal generator 453 are applied in formula 1, i.eTo calculate a first leakage current I flowing through the measuring resistor 432, 435 R.LK And the converted measured current value 452 and the reference signal generator 453 are applied to formula 2, i.e., I CT.LK ＝∫ 2π v NOR (θ)·i CT.LK (θ) dθ to calculate the second leakage current I flowing through the current detection device 420 CT.LK By calculating the first leakage current I R.LK And the second leakage current I CT.LK To obtain a current difference IDET, comparing an absolute value of the current difference IDET with a predetermined minute current Δi, determining that an insulating state is good when the absolute value of the current difference IDET is smaller than the predetermined minute current value Δi, and determining that the insulating state is bad when the absolute value of the current difference IDET is larger than the predetermined minute current value Δi.
The electrical device is characterized in that, when the plurality of sockets are used, a socket in which the ground insulation strength is reduced can be specified.
And, as a method for measuring an insulation state of a load on a plurality of sockets of a power supply branch of ground insulation, comprising: a) A calculation step (454) of applying the converted measurement voltage value (451) and the reference signal generator (453) to formula 1, namelyTo calculate a first leakage current (I) through the measuring resistor (432, 435) R.LK ) The method comprises the steps of carrying out a first treatment on the surface of the b) A calculation step (455) of applying the converted measured current value (452) and the reference signal generator (453) to formula 2, i.e. I CT.LK ＝∫ 2π v NOR (θ)·i CT.LK (θ) dθ to calculate a second leakage current (I) flowing through the current detection device (420) CT.LK ) The method comprises the steps of carrying out a first treatment on the surface of the c) A step (456) of calculating the first leakage current (I R.LK ) And the second leakage current (I CT.LK ) To obtain a current difference (I DET ) The method comprises the steps of carrying out a first treatment on the surface of the d) -comparing (458, 459) the absolute value of the current difference (IDET) with a predetermined small current value (Δi), determining that the insulation state is good when the absolute value of the current difference (IDET) is smaller than the predetermined small current value (Δi), and determining that the insulation state is bad when the absolute value of the current difference (IDET) is larger than the predetermined small current value (Δi); and e) displaying the processing step (460), and notifying the determination result of the insulation state to the outside.
The method for measuring the insulation state of the load on the plurality of sockets of the power supply branch which is grounded is characterized in that the measurement time for calculating the formula 1 and the formula 2 is more than one period and is an integer multiple of the period.
The method for measuring the insulation state of the load on the plurality of sockets of the power supply branch of the ground insulation is characterized in that the minute current value (DeltaI) as the insulation judgment standard can be changed according to the capacity of the system or the applicable environment and the range is not more than 50mA. The 50mA here is the limit capacity of a conventional earth leakage breaker and gives the maximum value of the sum for household and industrial use. When the method is practically applied to household use and industrial use, the method can be divided into 30mA use and 50mA use for realizing the productization.
ADVANTAGEOUS EFFECTS OF INVENTION
In the present invention, an electric device and method for measuring the insulation state of a load on a plurality of sockets branched from a power supply insulated from the ground has an effect in that, when a plurality of sockets are used, the insulation state of individual socket loads is measured to be able to designate a socket whose ground insulation strength is reduced, so that the cost and modification time can be reduced.
Also, only the individual sockets can be separated in a state where the entire power supply is not cut off, and thus the device operation time can be maintained, whereby an economical effect can be obtained.
Also, since the device capable of easily tracking the ground insulation deterioration position is provided, a large accident such as a fire or a personal injury can be prevented in advance.
Drawings
Fig. 1 is a state diagram of a ground-isolated power system 100 branching to a plurality of outlets 300, a.300-N and their corresponding loads 500, a.500-N, according to one embodiment of the invention;
fig. 2 is an internal structural view of an individual leakage measurement device 400, 400-N according to one embodiment of the present invention;
fig. 3 to 10 are state diagrams of leakage currents connected to a socket through check switches 431, 434 of a separate leakage measurement device according to an embodiment of the present invention; and
FIG. 11 is a flow chart of the calculation of a microprocessor in a single leak measurement apparatus in accordance with one embodiment of the invention.
Detailed Description
The invention is capable of being practiced with various modifications, specific embodiments are shown in the drawings and described in detail. It should be understood, however, that there is no intention to limit the invention to the specific embodiments, but it is to be understood that the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.
In describing the various drawings, like reference numerals are used for like structural elements. In describing the present invention, if it is considered that detailed description of related known techniques can obscure the gist of the present invention, detailed description thereof will be omitted.
The invention can provide the following scheme: when a plurality of sockets are grounded to an insulated power supply to obtain electric power, since the insulation degradation state of the electrical device is measured in the connected individual sockets, the position of the insulation degraded electrical device can be found as easily as possible, so that time and effort to be able to solve the failure can be reduced.
Fig. 1 outlines a power supply and load to which the present invention is applicable, the power supply system 100 supplies power to respective loads 500, 500-1, 500-N through an insulation transformer 200 for ground insulation and individual sockets 300, 300-1. At this time, the insulation state of the respective loads 500, 500-1, 500-N is measured per each outlet 300, 300-1, 300-N, and individual leakage measuring devices (400, 400-1, 400-N) for which the insulation state needs to be determined are displayed. For example, if the ground insulation state of the load 500 is deteriorated, the individual leakage measurement device 400 determines that the load is to be taken, and the load is notified to the outside by a display device, a communication device, or the like built in the load.
Fig. 2 is an example of the internal circuitry of a single-phase leakage measurement device 400 according to one embodiment of the invention, describing a single-phase input, but this may be applied to three phases as the same principle. The two power sources including the ground input to the input terminal 410 are connected to the output terminal 440 via a current detection device 420 for measuring current in the two power sources other than the ground and a voltage detection device 430 drawn from each of the two power lines. The current detection device 420 is used for measuring the difference of the current flowing through the head line, and the measured current is converted into a voltage by the operational amplifier 421 and is converted by an analog-to-digital converter built in the microprocessor 450. The two voltages input from the voltage detection device 430 are grounded through each of the inspection switches 431 and 434 and the measurement resistors 432 and 435, and the voltages between the ground and the power supply are distributed at the same ratio in the measurement resistors 432 and 435, and are converted by analog-to-digital converters built in the microprocessor 430 through the insulating amplifiers 433 and 436. The measuring resistances 432 and 435 are set to sufficiently large values, and electric shock and the like can be safely avoided. If an abnormality occurs in the ground insulation in the load connected to the output terminal 440, a notification such as a buzzer, a warning lamp, or communication is made by the display processing unit 460 to perform a measure. The communication at this time may be arbitrarily selected from power line communication, limited wireless communication, and the like.
Fig. 3 is a conceptual diagram of an operation form of the individual leakage measuring device 400 in fig. 2, and although a position of a load or the like is changed for convenience, there is no difference in an operation structure of a circuit since it is connected to the same power line. The individual leakage measurement device 400 is shown in dashed lines with check switches 431, 434 operating intermittently to connect each power line to a measurement resistor 432, 435. At this time, the check switch 431 and the check switch 434 are not operated at the same time, but alternately operated. As shown in fig. 3, if the power-ground resistance does not occur at the output side of the socket 300 including the load 500, current does not flow to the measurement resistor 432 through the check switch 431, and the measurement voltage of the measurement resistor 432 may be "0". Since there is no current flowing through the current sensor 420, the output voltage of the operational amplifier 421 measuring the current value may be "0".
Fig. 4 shows a case where the operation of the inspection switch 431-1 of the socket 420-1 provided with the individual leakage measuring device is repeated among the plurality of sockets, and shows a case where the inspection switch 431 of the individual leakage measuring device 400 is operated simultaneously with the inspection switch 431-1 of the individual leakage measuring device 400-1, at which time no current flows, so that no voltage occurs in the measuring resistor 432 and no voltage is measured in the operational amplifier 421. At this time, when the check switch 431 of the individual leakage measurement device 400 and the check switch 434-1 of the individual leakage measurement device 400-1 are operated, a voltage other than "0" is detected in the measurement resistor 432, and a current is also detected in the current detection device, and the phenomenon at this time is the same as that of fig. 7, and thus is included in the description of fig. 7.
Fig. 5 shows a case where a resistor or impedance 600 showing an insulation break appears in the output terminal of the individual leakage measurement device 400, that is, a case where the ground insulation is deteriorated, and when the inspection switch 431 is operated, a leakage current path 601 from the power supply 200 to the inspection switch 431, the measurement resistor 432, the resistor or impedance 600 showing a ground or insulation break, to the power supply flows, and a voltage is obtained at the measurement resistor 432. The resistance value of the measuring resistor 432 is known, so that the first leakage current I can be calculated from the measured voltage according to equation 1 R.LK The first leakage current I R.LK Is a one-cycle average of the current flowing through leakage current path 601. Constant terms such as 2pi are not included for convenience.
Equation 1:
wherein I is R.LK Is a first leakage current, which is a periodic average of the detected voltage;
v NOR (θ): normalization with power supply parityA sine wave;
v R.LK (θ): the voltage across the resistor (R11),
and, the second leakage current I can be obtained from equation 2 CT.LK Which is a periodic average of the current detected in the current detection means 420.
Equation 2: i CT.LK ＝∫ 2π v NOR (θ)·i CT.LK (θ)dθ
Wherein I is CT.LK Is a second leakage current, which is a periodic average of the detected current;
v NOR (θ): a sine wave co-located with the power supply;
i CT.LK : the current detected by the current detection means 420,
also, the insulation state of the specific socket 300 and the load connected to the individual leakage measuring device 400 may be determined according to equation 3.
Equation 3:
I DET ＝I R.LK -I CT.LJ
if the current difference IDET value is 0, it is determined that the insulation of the load connected to the preset socket 300 is in a good state, and if the current difference IDET value is not 0, it is determined that the insulation resistance between the ground and the power line occurs to the load connected to the socket 300. However, even in normal cases, insulation resistance occurs in all electrical devices, and therefore it is necessary to set some range on the leakage state determination, and it is necessary to set it in an adjustable form.
When the determination method of the above-described formulas 1 to 3 is applied to fig. 5,
due to I R.LK >0，I CT.LK =0, thus idet=i can be obtained R.LK -I CT.LK >0, and the connected load may be determined that the insulating state between the ground and the power supply line is poor.
Fig. 6 is a diagram showing that a single leakage measuring device to which the present invention is applied is connected in parallel to a plurality of same power sources 200, and leakage current flows when check switches 431, 431-1 are simultaneously operated. Leakage current flowing through the insulation broken resistor or impedance 600 has two paths 601, 602. First, the first leakage current ir.lk and the second leakage current ict.lk obtained by the current detection device 420 may be obtained from the leakage current obtained by the leakage current path 601, with the following results.
Due to I R.LK >0，I CT.LK ＝I CT.LK 601+I CT.LK 602<0, thus (taking into account the current direction) idet=i can be obtained R.LK -I CT.LK >0, and the connected load may be determined that the insulating state between the ground and the power supply line is poor. At this point, it should be noted that I of the current flowing through leakage current path 602 is calculated CT.LK 602 has a negative value, as is apparent in equation 2.
Fig. 7 is a diagram showing a leakage current path when the inspection switch 431 of the individual leakage measurement device 400 operates when the ground insulation state of the load of the receptacle 300-1 is deteriorated in the same connection environment as in fig. 5. Leakage current flows along current path 603, at which time a measured first leakage current I R.LK Second leakage current I CT.LK The following is provided.
Due to I R.LK >0，I CT.LK ＝I R.LK >0, thus idet=i can be obtained R.LK -I CT.LK =0, the load connected to the individual leakage measurement device 400 may be determined that the ground insulating state is good.
Fig. 8 is a leakage current flow chart when the inspection switch 431 of the individual leakage measurement device 400 is operated simultaneously with the inspection switch 431-1 of the adjacent individual leakage measurement device 400-1, having two leakage currents 603, 604, when there is a ground insulation resistance in the load end of the socket 420-1 provided with the individual leakage measurement device, and when the current value through the first leakage current path 603 appearing in the individual leakage measurement device 400 is as follows.
Due to I R.LK >0，I CT.LK ＝I R.LK >0, thus idet=i can be obtained R.LK -I CT.LK =0. The second leakage current path 604 does not affect the individual leakage measurement device 400, and is therefore not reflected in the operation. Finally, is connected withThe current difference IDET in the load of the individual leakage measurement device 400 is "0", and thus the load connected to the outlet 300 can determine that the ground insulating state is good.
Fig. 9 is a diagram showing a case where only the check switch 431 of the individual leakage measurement device 400 is operated in a case where there is a ground insulation resistance in the two or more sockets 300, 300-1, showing two leakage current paths 601, 602, the first leakage current I measured in the individual leakage measurement device 400 R.LK Second leakage current I CT.LK Can be obtained as follows.
Due to I R.LK ＝I R.LK 601+I R.LK 603>0，I CT.LK ＝I R.LK 603>0, thus idet=i can be obtained R.LK -I CT.LK ＝I R.LK 601>0. As can be seen from calculations, the load connected to the receptacle 300 presents a ground insulation resistance and requires repair or action. While knowing the ground insulating state intersection of the load connected to the other receptacle 300-1, its exact location cannot be specified, which is a matter that needs to be confirmed by the separate leakage measurement device 400-1 connected to the other receptacle 300-1.
Fig. 10 shows a case where there are ground insulation resistances in two or more sockets 300, 300-1, the check switches 431, 431-1 of the individual leakage measurement devices 400, 400-1 connected to each socket 300, 300-1 are operated simultaneously, and there are a total of four insulation broken resistances or impedances 600-1, 600-2, 600-3, 600-4, wherein one leakage path 604 does not have any influence on the measurement of the individual leakage measurement devices 400, and thus can be ignored. First, when the inspection switch 431 of the individual leakage measuring device 400 is operated, the first leakage current I detected by the voltage detecting device 430 R.LK The current is measured by two leakage current paths 601, 603, a second leakage current I measured by the current detection means 420 CT.LK The current is measured through a total of three leakage current paths 601, 602, 603. At this time, the currents through the leakage current path 601 cancel each other out at the current detection device 420, so the current measured by the current detection device 420 measures the leakage current through the leakage paths (602, 603), which measures the junctionThe results are as follows.
Due to I R.LK ＝I R.LK 601+I R.LK 603>0，I CT.LK ＝I CT.LK 602+I CT.LK 603, and thus,
IDET＝I R.LK -I CT.LK
＝I R.LK 601+I R.LK 603-I CT.LK 602-I CT.LK 603，
wherein I is R.LK 603＝I CT.LK 603, thus canceling each other, the current difference IDET is as follows.
IDET＝I R.LK 601-I CT.LK 602
As can be seen from the figure, I CT.LK 602 has a negative value, and thus, as a result, IDET has a positive value other than "0", the load connected to the outlet 300 can be determined that there is an abnormality in the ground insulating state.
Fig. 11 is a flowchart showing the result obtained from the above series of logical matters programmed in the microprocessor 450 in the individual leakage measuring device 400, the output of the insulated amplifiers 433, 436 are converted by the analog-digital converter in the microprocessor 450 to obtain the voltage measurement value (451), the output of the operational amplifier 420 is also ADC-converted to obtain the current measurement value (452), phase-synchronized with the power supply, a prescribed reference signal is generated (453), the obtained voltage measurement value and reference signal are periodically integrated according to formula 1 to be averaged (454), the obtained current measurement value and reference signal are periodically integrated according to formula 2 to be averaged (455), the results of the two formulas are calculated according to formula 3 to obtain the current difference value IDET (456), the insulated state is judged to be good when the absolute value of the thus obtained current difference value IDET is a predetermined minute current Δi or less, the absolute value of the current difference value IDET is larger than the predetermined minute current Δi is judged to be bad (458), and the sound communication is judged to be bad (461) by the external device, the communication device.
Although the invention has been described with respect to a single phase in terms of its construction and method of operation, it will be readily appreciated that this can be applied to three phases in the same manner of operation. That is, the present invention is a technical solution that can be conventionally used for single phase, three phase and above phases, and a multiphase system is applied without departing from the scope of the present invention.
Description of the reference numerals
100: power supply system
200: insulating transformer
300 300-1, 300-N: socket
400 400-1, 400-N: individual leakage measurement device
500 500-1, 500-N: load connected to each socket
600, 600-1: resistance or impedance to breakage of insulation
410: input terminal
420: current detection device
430: voltage detection device
440: an output terminal
450: microprocessor
460: display processing unit
421: operational amplifier
431. 431-1, 434: inspection switch
432. 432-1, 435: measuring resistance
433. 436: insulated amplifier
451: analog-to-digital converter (ADC) converted voltage measurement
452: analog-to-digital converter (ADC) converted current measurement
453: sine wave reference signal generator
454: equation 1
455: equation 2
456: equation 3
457: current difference IDET determination
458: good-insulation-state path
459: path of poor insulation state
461: insulation state result processing block
601. 602, 603, 604: leakage current path.
Claims (5)
1. An electrical device for measuring the insulation status of loads on a plurality of sockets of a ground-insulated power supply branch, the electrical device comprising an individual leakage measurement device (400), the electrical device being characterized in that,
the individual leakage measurement device (400) comprises:
a current measuring device (420) for measuring a current difference flowing through two power lines at the same time using a core, or ferrite, or current-withstanding test method;
voltage measuring means (430) for measuring the voltage everywhere;
check switches (431, 434) for alternately operating the respective voltage measuring devices, each voltage measuring device having an operating time of one cycle or more;
an insulating amplifier (433, 436) for measuring the voltage at the measuring resistor (432, 435);
an operational amplifier (421) directly connected to the current measuring device (420) for converting a current into a voltage and outputting the voltage to a microprocessor (450) for judging a ground insulation state of a load;
the microprocessor (450) is used for performing analog-digital converter conversion on the output of the operational amplifier (421) and the output of the insulation amplifiers (433, 436) and judging the grounding insulation state of the connected load through internal calculation; and
a display processing unit (460) for notifying the determination result of the insulation state to the outside,
wherein in the microprocessor (450), the converted measurement voltage value (451) and the reference signal generator (453) are applied to equation 1, i.eTo calculate a first leakage current (I) through the measuring resistor (432, 435) R.LK ) And the converted measured current value (452) and the reference signal generator (453) are applied in equation 2, i.e. +.>To calculate a second leakage current (I) flowing through the current detection device (420) CT.LK ) By calculating the first leakage current (I R.LK ) And the second leakage current (I CT.LK ) To obtain a current difference value (IDET), comparing an absolute value of the current difference value (IDET) with a predetermined minute current value (Δi), determining that an insulating state is good when the absolute value of the current difference value (IDET) is smaller than the predetermined minute current value (Δi), and determining that the insulating state is bad when the absolute value of the current difference value (IDET) is larger than the predetermined minute current value (Δi).
2. The electrical device for measuring the insulation state of a load on a plurality of sockets of a power supply branch of ground insulation according to claim 1, wherein when the plurality of sockets are used, a socket in which the ground insulation strength is reduced can be specified.
3. A method for measuring the insulation status of a load on a plurality of receptacles of a ground-insulated power supply branch, comprising:
a) A calculation step (454) of applying the converted measurement voltage value (451) and the reference signal generator (453) to formula 1, namelyTo calculate a first leakage current (I) through the measuring resistor (432, 435) R.LK )；
b) A calculation step (455) of applying the converted measured current value (452) and the reference signal generator (453) to equation 2, i.eTo calculate a second leakage current (I) flowing through the current detection device (420) CT.LK )；
c) A step (456) of calculating the first leakage current(I R.LK ) And the second leakage current (I CT.LK ) To obtain a current difference (I DET )；
d) -comparing (458, 459) the absolute value of the current difference (IDET) with a predetermined small current value (Δi), determining that the insulation state is good when the absolute value of the current difference (IDET) is smaller than the predetermined small current value (Δi), and determining that the insulation state is bad when the absolute value of the current difference (IDET) is larger than the predetermined small current value (Δi); and
e) And a display processing step (460) of notifying the determination result of the insulation state to the outside.
4. A method for measuring the insulation status of a load on a plurality of receptacles of a ground-isolated power branch as claimed in claim 3,
the measurement time for calculating the formula 1 and the formula 2 is one cycle or more and is an integer multiple of the cycle.
5. A method for measuring the insulation state of a load on a plurality of sockets of a power supply branch which is grounded according to claim 3, characterized in that the minute current value (Δi) as an insulation judgment criterion can be changed according to the capacity of the system or the applicable environment and the range is not more than 50mA.
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| KR1020220103805A KR102495186B1 (en) | 2022-08-19 | 2022-08-19 | Electrical apparatus and method for measuring leakage state of each concent multiply connected to source |
| KR10-2022-0103805 | 2022-08-19 |
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| KR20030010582A (en) | 2000-02-22 | 2003-02-05 | 산요 덴키 가부시키가이샤 | Circuit for detecting leakage in power supply |
| KR101227658B1 (en) * | 2011-10-11 | 2013-01-29 | 주식회사 위너스 | Concent for cutting off the standby-power |
| KR101183617B1 (en) * | 2012-02-02 | 2012-09-18 | 주식회사 위너스 | Multi-tap concent for cutting off standby-power and leakage current |
| JP5631444B1 (en) * | 2013-05-27 | 2014-11-26 | タナシン電機株式会社 | Leakage current calculation device and leakage current calculation method |
| KR20190122444A (en) | 2018-04-20 | 2019-10-30 | (주) 미디어스트림 | System for earth leakage circuit breaking |
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| KR102495186B1 (en) * | 2022-08-19 | 2023-02-06 | 송종환 | Electrical apparatus and method for measuring leakage state of each concent multiply connected to source |
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