CN217787278U - Insulation fault detection device - Google Patents
Insulation fault detection device Download PDFInfo
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- CN217787278U CN217787278U CN202221672644.1U CN202221672644U CN217787278U CN 217787278 U CN217787278 U CN 217787278U CN 202221672644 U CN202221672644 U CN 202221672644U CN 217787278 U CN217787278 U CN 217787278U
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Abstract
The utility model discloses an insulation fault detection device is applied to DC power supply system, and this system includes positive DC bus, burden DC bus and a plurality of load branch roads of being connected with positive DC bus and burden DC bus respectively, and the device includes: the switching unit comprises a switching unit and a detection unit, wherein a first end of the switching unit is connected with the positive direct-current bus, a second end of the switching unit is connected with the negative direct-current bus, a third end of the switching unit is grounded, and the detection unit is respectively connected with the positive direct-current bus and the negative direct-current bus; the switching unit is used for switching resistance values; the detection unit is used for detecting the leakage current value on the load branch under the switching units with different resistance values and converting the leakage current value into a voltage value.
Description
Technical Field
The utility model relates to an electric power overhauls technical field, in particular to insulation fault detection device.
Background
The insulation performance of a positive direct current bus and a negative direct current bus of a power system to the ground is reduced along with the aging of electric equipment or the influence of external factors, and the reduction of the insulation performance may cause the misoperation of a relay protection device on the output side of the direct current system, thereby causing power utilization safety accidents.
Generally, a fixed insulation monitor is designed in a high-voltage direct-current system, but the fixed insulation monitor can only give an alarm when detecting that the resistance to ground is lower than 25K Ω (ohm), and can not give an alarm when the resistance to ground is higher than 25K Ω (ohm), namely, when an insulation fault occurs, but the resistance to ground is higher than 25K Ω, the fixed insulation monitor can not detect the insulation fault.
In conclusion, the existing fixed insulation monitor is inaccurate in insulation fault detection.
SUMMERY OF THE UTILITY MODEL
The utility model provides an insulation fault detection device for solve the unsafe problem of insulation fault detection that exists among the prior art.
In a first aspect, an embodiment of the present invention provides an insulation fault detection device, which is applied to a dc power supply system, the dc power supply system includes a positive dc bus, a negative dc bus and a plurality of load branches connected to the positive dc bus and the negative dc bus respectively, the device includes: a switching unit and a detection unit, wherein,
a first end of the switching unit is connected with the positive direct-current bus, a second end of the switching unit is connected with the negative direct-current bus, a third end of the switching unit is grounded, and the detection unit is respectively connected with the positive direct-current bus and the negative direct-current bus;
the switching unit has a resistance value switching function;
the detection unit is used for detecting the leakage current value on the load branch circuit under the switching units with different resistance values, converting the leakage current value into a voltage value, so that a detector can obtain the resistance values of a plurality of grounding resistors according to the different resistance values of the switching units, a plurality of voltage values and a preset corresponding relation, and judge whether the load branch circuit has an insulation fault according to the obtained resistance values of the grounding resistors.
In one possible embodiment, the switching unit comprises a first switching subunit and a second switching subunit, wherein,
the first end of the first switching subunit is connected with the positive direct-current bus, the second end of the first switching subunit is grounded, the first end of the second switching subunit is connected with the negative direct-current bus, and the second end of the second switching subunit is grounded.
In one possible embodiment, the first switching subunit comprises a plurality of first resistors and a first switching element, wherein,
a first end of each first resistor is used as a first end of the first switching subunit, and a second end of each first resistor is connected with a first end of the first switch component; a second end of the first switch component is used as a second end of the first switching subunit;
the second switching subunit comprises a plurality of second resistors and a second switch component, wherein,
a first end of each second resistor is used as a first end of the second switching subunit, and a second end of each second resistor is connected with a first end of the second switch component; a second end of the second switch component is used as a second end of the second switching subunit;
the first switch component is used for switching the resistance value of the first switching subunit;
and the second switch component is used for switching the resistance value of the second switching subunit.
In a possible implementation manner, the number of the first resistors and the number of the second resistors are two, and the two first resistors have different resistance values, and the two second resistors have different resistance values.
In one possible embodiment, the first switch assembly comprises a first switch and a second switch, wherein,
the first switch is connected with one first resistor in series, a first end after series connection is used as a first end of the first switching subunit, and a second end after series connection is used as a second end of the first switching subunit; the second switch is connected with the other first resistor in series, a first end after series connection is used as a first end of the first switching subunit, and a second end after series connection is used as a second end of the first switching subunit;
the second switch assembly includes a third switch and a fourth switch, wherein,
the third switch is connected with one second resistor in series, a first end after series connection is used as a first end of the second switching subunit, and a second end after series connection is used as a second end of the second switching subunit; and the fourth switch is connected with the other second resistor in series, a first end after series connection is used as a first end of the second switching subunit, and a second end after series connection is used as a second end of the second switching subunit.
In one possible embodiment, the first switch assembly is a first single pole, double throw switch, wherein,
a first end of the first single-pole double-throw switch is connected with a first end of one first resistor, a second end of the first single-pole double-throw switch is connected with a first end of the other first resistor, and a third end of the first single-pole double-throw switch is used as a second end of the first switching subunit; the second end of one first resistor is connected with the second end of the other first resistor to serve as the first end of the first switching subunit;
the second switch assembly is a second single pole double throw switch, wherein,
a first end of the second single-pole double-throw switch is connected with a first end of one of the second resistors, a second end of the second single-pole double-throw switch is connected with a first end of the other one of the second resistors, and a third end of the second single-pole double-throw switch is used as a second end of the second switching subunit; and the second end of one second resistor is connected with the second end of the other second resistor to serve as the first end of the second switching subunit.
In one possible embodiment, the first switching subunit is a sliding varistor, and/or
The second switching subunit is a sliding rheostat.
In one possible embodiment, the detection unit comprises a current collection module and a voltage display module, wherein,
the power supply end of the current acquisition module is connected with an external power supply end, the output end of the current acquisition module is connected with the voltage display module, the first input end of the current acquisition unit is connected with the positive direct-current bus, and the second input end of the current acquisition unit is connected with the negative direct-current bus;
the current acquisition module is used for acquiring a leakage current value on the load branch, converting the leakage current value into a voltage signal and sending the voltage signal to the voltage display module;
and the voltage display module is used for displaying the voltage value corresponding to the leakage current according to the voltage signal. In one possible embodiment, the current collection module is a dc transmitter.
In one possible embodiment, the voltage display module is a voltmeter.
The utility model discloses beneficial effect as follows:
the utility model discloses an insulation fault detection device is applied to DC power supply system, and this system includes positive DC bus, burden DC bus and a plurality of load branch roads of being connected with positive DC bus and burden DC bus respectively, and the device includes: the switching unit comprises a switching unit and a detection unit, wherein the first end of the switching unit is connected with a positive direct current bus, the second end of the switching unit is connected with a negative direct current bus, the third end of the switching unit is grounded, and the detection unit is respectively connected with the positive direct current bus and the negative direct current bus of the direct current power supply system; the switching unit is used for switching resistance values; the detection unit is used for detecting the leakage current value on the load branch circuit under the switching units with different resistance values, converting the leakage current value into a voltage value, so that a plurality of ground resistance values can be obtained by a detection person according to the different resistance values, the plurality of voltage values and a preset corresponding relation of the switching units, and whether the insulation fault exists in the load branch circuit can be judged according to the obtained resistance values of the plurality of ground resistances. Because the utility model provides a switching unit has the resistance and switches the function, consequently can obtain different magnitude of voltage under the switching unit of different resistances, and the predetermined corresponding relation of rethread obtains a plurality of ground resistance resistances, judges whether there is insulation fault according to a plurality of resistances that obtain at last to improve insulation fault's detection precision.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without inventive exercise.
Fig. 1 is a schematic diagram of a dc power supply system in the related art;
fig. 2 is a schematic structural diagram of an insulation fault detection apparatus according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of an insulation fault detection apparatus according to an embodiment of the present invention;
fig. 4a is a schematic structural diagram of another insulation fault detection apparatus according to an embodiment of the present invention;
fig. 4b is a schematic structural diagram of another insulation fault detection apparatus according to an embodiment of the present invention;
fig. 5 is a schematic diagram of a specific structure of a detection unit according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.
As shown in fig. 1, a schematic diagram of a dc power supply system in the related art includes a positive dc bus 101, a negative dc bus 102, and a plurality of loads 103 connected to the positive dc bus 101 and the negative dc bus 102, respectively. The branch where each load is located is a load branch, and each load is connected between the positive direct current bus 101 and the negative direct current bus 102.
The direct current power supply system is an independently arranged part in the power system, mainly comprises direct current equipment such as a storage battery pack, charging equipment, a direct current screen and a feed network, and is mainly used for supplying power to secondary equipment such as a relay protection device, an automatic device and a signal loop in the power system. In order to meet the requirement of stable operation of a power system, a direct current power supply system can reliably and uninterruptedly supply power to electric equipment under any condition. The most common fault in dc power supply systems is a reduction in the insulation performance, i.e. an insulation fault. The reduction of the insulation performance may cause the malfunction of a relay protection device on the output side of the direct current system, thereby causing a power utilization safety accident.
At present, a fixed insulation monitor of a high-voltage direct-current system only gives an alarm when detecting that the ground resistance of a direct-current bus is lower than 25K omega, so that an insulation fault alarm system higher than 25K omega can be automatically ignored, and the alarm risk caused by insufficient measurement accuracy of a sensor exists.
Based on the problem, the embodiment of the utility model provides an insulation fault detection device for solve the unsafe problem of prior art insulation fault detection.
The insulation fault detection apparatus provided by the exemplary embodiment of the present application is described below with reference to the accompanying drawings in conjunction with the application scenarios described above, it should be noted that the above application scenarios are only shown for the convenience of understanding the spirit and principles of the present application, and the embodiments of the present application are not limited in this respect.
As shown in fig. 2, for the utility model provides a structural schematic diagram of an insulation fault detection device, the device includes switching unit 201 and detecting element 202:
a first end of the switching unit 201 is connected with the positive direct-current bus 101, a second end of the switching unit 201 is connected with the negative direct-current bus 102, a third end of the switching unit 201 is grounded, and the detection unit 202 is respectively connected with the positive direct-current bus 101 and the negative direct-current bus 102;
the switching unit 201 has a resistance value switching function;
the detecting unit 202 is configured to detect a leakage current value on the load branch 103 in the switching unit 201 with different resistances, and convert the leakage current value into a voltage value, so that a tester obtains the resistances of the multiple ground resistors according to the different resistances of the switching unit, the multiple voltage values, and a preset corresponding relationship, and judges whether the load branch has an insulation fault according to the resistances of the multiple ground resistors.
The embodiment of the utility model provides an insulation fault detection device is applied to DC power supply system, and this DC system includes positive DC bus, burden DC bus and a plurality of load branch roads of being connected with positive DC bus and burden DC bus respectively, and the device includes: the switching device comprises a switching unit and a detection unit, wherein the first end of the switching unit is connected with a positive direct-current bus, the second end of the switching unit is connected with a negative direct-current bus, the third end of the switching unit is grounded, and the detection unit is respectively connected with the positive direct-current bus and the negative direct-current bus; the switching unit is used for switching resistance values; and the detection unit is used for detecting the leakage current value on the load branch circuit under the switching units with different resistance values, converting the leakage current value into a voltage value, so that a detector can obtain the resistance value of the ground resistor according to the different resistance values, the multiple voltage values and the preset corresponding relation of the switching units, and judge whether the load branch circuit has an insulation fault according to the obtained resistance values of the multiple ground resistors. Because the switching unit has the resistance value switching function, a plurality of grounding resistance values can be obtained through a preset corresponding relation under the switching units with different resistance values, and whether an insulation fault exists is judged according to the obtained plurality of resistance values, so that the detection precision of the insulation fault is improved.
The specific structure of the insulation fault detection apparatus is explained in detail below:
as shown in fig. 3, for the embodiment of the present invention provides a specific structural schematic diagram of an insulation fault detection device, and with reference to fig. 2, the switching unit 201 may include a first switching subunit 301 and a second switching subunit 302, and the connection mode is as follows: a first end of the first switching subunit 301 is connected to the positive dc bus 101, a second end of the first switching subunit 301 is grounded, a first end of the second switching subunit 302 is connected to the negative dc bus 102, and a second end of the second switching subunit 302 is grounded.
Specifically, the first switching subunit 301 may include a plurality of first resistors R1 and a first switch component 3011, and the second switching subunit 302 may include a plurality of second resistors R2 and a second switch component 3021, and the connection manner is as follows:
a first end of each first resistor R1 is used as a first end of the first switching subunit 301, and a second end of each first resistor R1 is connected to a first end of the first switch component 3011; a second end of the first switch component 3011 serves as a second end of the first switching subunit 301;
a first end of each second resistor R2 is used as a first end of the second switching subunit 302, and a second end of each second resistor R2 is connected to a first end of the second switch assembly 3021; a second end of the second switch assembly 3021 serves as a second end of the second switching subunit 302;
the first switch component 3011 is configured to switch the resistance of the first switching subunit 301;
and the second switch assembly 3021 is configured to switch the resistance value of the second switching subunit 302.
The following explanation is continued by taking the example that the number of the first resistors R1 and the number of the second resistors R2 are two:
as shown in fig. 4a, for another insulation fault detection device provided by the embodiment of the present invention has a specific structure, wherein the resistance of two first resistors is different, and the resistance of two second resistors is different, for example, the resistance of the first resistor R1 is 30K Ω, the resistance of the first resistor R1 'is 15K Ω, the resistance of the second resistor R2 is 30K Ω, and the resistance of the second resistor R2' is 15K Ω.
The first switch assembly 3011 may include a first switch 401 and a second switch 402, and the second switch assembly 3021 includes a third switch 403 and a fourth switch 404, which are connected as follows:
the first switch 401 is connected in series with a first resistor R1, a first end of the first switch subunit 301 after the series connection is used as a first end of the first switch subunit 301, and a second end of the first switch subunit 301 after the series connection is used as a second end of the first switch subunit 301; the second switch 402 is connected in series with another first resistor R1', a first end of the series connection is used as a first end of the first switching subunit 301, and a second end of the series connection is used as a second end of the first switching subunit 301;
the third switch 403 is connected in series with a second resistor R2, a first end of the series connection is used as a first end of the second switching subunit 302, and a second end of the series connection is used as a second end of the second switching subunit 302; the fourth switch 404 is connected in series with another second resistor R2', a first end of the series connection is used as a first end of the second switching subunit 302, and a second end of the series connection is used as a second end of the second switching subunit 302.
It should be noted that, as shown in fig. 4b, for a specific structural schematic diagram of another insulation fault detection apparatus provided in the embodiment of the present invention, the first switch component 3011 may also be a first single-pole double-throw switch 405, wherein,
a first end of the first single-pole double-throw switch 405 is connected with a first end of one first resistor R1, a second end of the first single-pole double-throw switch 405 is connected with a first end of another first resistor R1', and a third end of the first single-pole double-throw switch 405 is used as a second end of the first switching subunit 301; the second end of one first resistor R1 is connected to the second end of another first resistor R1' to serve as the first end of the first switching subunit 301;
the second switch assembly 3021 may also be a second single pole, double throw switch 406, wherein,
a first end of the second single-pole double-throw switch 406 is connected with a first end of one second resistor R2, a second end of the second single-pole double-throw switch 406 is connected with a first end of the other second resistor R2', and a third end of the second single-pole double-throw switch 406 is used as a second end of the second switching subunit 302; the second end of one second resistor R2 is connected to the second end of another second resistor R2' to serve as the first end of the second switching subunit 302.
It should be noted that the first switching subunit and the second switching subunit may be variable resistors, such as a sliding rheostat or a resistor box. And the resistance values of the first switching subunit and the second switching subunit are changed through the variable resistor.
As shown in fig. 5, for the embodiment of the present invention provides a specific structural schematic diagram of a detecting unit, the detecting unit 202 includes a current collecting module 501 and a voltage displaying module 502:
a current collecting module 501, configured to collect a leakage current value on the load branch 103;
the voltage display module 502 is configured to convert the leakage current value into a voltage value and display the voltage value.
The connection mode is as follows:
the power supply end of the current collection module 501 is connected with an external power supply end, for example, through a power adapter and a mains input connection, so as to supply power to the current collection module 501, the output end of the current collection module 501 is connected with the voltage display module 502, the first input end of the current collection module 501 is connected with the positive dc bus 101, and the second input end of the current collection module 501 is connected with the negative dc bus 102.
It should be noted that the current collecting unit here may be a direct current transmitter, such as an open type hall transmitter, and the hall transmitter may detect a leakage current at a milliampere level of-10 mA to +10mA, and convert the leakage current signal into a voltage signal according to a certain proportion, such as sending the voltage signal to the voltage display module in a form of a voltage signal of-4V to + 4V;
in addition, the voltage display module 502 here may be a voltmeter, which can visually display the voltage signal sent by the hall transmitter, where the voltage value includes a positive voltage and a negative voltage, the positive voltage represents that the positive dc bus decreases in insulation to ground, and the negative voltage represents that the negative dc bus decreases in insulation to ground, so as to further confirm the resistance value of the ground resistor corresponding to the load by combining with a preset insulation fault table.
Specifically, the insulation instrument main machine connected with the direct current power supply system is firstly closed, namely the bridge unit of the system is withdrawn from the system. Then will the utility model provides an insulation fault detection device is connected with DC power supply system according to above-mentioned mode.
The method comprises the steps of measuring leakage current of a load branch by using an open type Hall transmitter, enabling a positive bus and a negative bus of the load branch to penetrate through the open type Hall transmitter, switching the resistance value of a first switching subunit into a first resistance value, switching the resistance value of a second switching subunit into a second resistance value, recording a first voltage value displayed by a voltmeter at the moment, and confirming the resistance value of a grounding resistor corresponding to the load branch by combining a preset insulation fault meter.
And switching the resistance value of the first switching subunit into a third resistance value, switching the resistance value of the second switching subunit into a fourth resistance value, recording a second voltage value displayed by the voltmeter at the moment, and further confirming the resistance value of the ground resistor by combining a preset insulation fault meter.
The resistance value of the grounding resistor corresponding to the load branch is confirmed to be the approximate resistance value of the grounding resistor for the first time, the resistance value switched by the switching unit is switched in a targeted manner according to the approximate resistance value of the grounding resistor for the second time, and after the switching, the accurate grounding resistor value is obtained according to the second voltage value displayed by the voltmeter and by combining a preset insulation fault table, so that the accurate branch insulation fault condition can be obtained by confirming the resistance value of the grounding resistor twice.
For example, referring to fig. 5, the resistance of the resistor R1 of the first switching subunit 301 is 30K Ω, the resistance of the resistor R1 'is 15K Ω, the resistance of the resistor R2 of the second switching subunit 302 is 30K Ω, and the resistance of the resistor R2' is 15K Ω;
after the insulation fault detection device is connected to a direct-current power supply system, the switch 401 and the switch 402 are closed, at this time, the current collection module 501 collects leakage current of the direct-current power supply system, the voltage display module 502 displays that the voltage value is +1.95V, namely, the leakage current exists in a positive direct-current bus, insulation fault may occur, the leakage voltage is 1.95V, when R1= R2=30K Ω, a preset correspondence table of the voltage value of the positive direct-current bus and a fault resistance value is obtained, namely, table 1, and the fault resistance value is 30K Ω.
| Numbering | Voltage (V) | Fault resistance value (K omega) |
| 1 | 1.5 | 500 |
| 2 | 1.55 | 250 |
| 3 | 1.6 | 150 |
| 4 | 1.65 | 100 |
| 5 | 1.7 | 80 |
| 6 | 1.75 | 60 |
| 7 | 1.8 | 50 |
| 8 | 1.85 | 40 |
| 9 | 1.9 | 35 |
| 10 | 1.95 | 30 |
TABLE 1
After the first measurement is completed, the switch 401 and the switch 403 are opened, the switch 402 and the switch 404 are closed, the ground voltage of the bus is measured again, at this time, the current collection module 501 collects the leakage current of the dc power supply system, the voltage display module 502 displays that the voltage value is +3.52V, that is, the leakage current exists in the positive dc bus, which may cause an insulation fault, the leakage voltage is 3.52V, and when R1'= R2' =15K Ω is combined, a preset correspondence table between the voltage value of the positive dc bus and the fault resistance value, that is, table 2, obtains the fault resistance value of 30K Ω.
| Numbering | Voltage (V) | Fault resistance value (K omega) |
| 1 | 2.97 | 580 |
| 2 | 3.02 | 250 |
| 3 | 3.07 | 150 |
| 4 | 3.14 | 100 |
| 5 | 3.2 | 75 |
| 6 | 3.36 | 44 |
| 7 | 3.44 | 36 |
| 8 | 3.52 | 30 |
TABLE 2
Comparing the two obtained resistance values, and determining that the grounding branch of the positive direct current bus has an insulation fault because the resistance values obtained twice are both 30K.
It should be noted that, for convenience of example, table 1 and table 2 only provide several sets of preset corresponding relationships between voltage values and fault resistance values, and in practical applications, more and more detailed corresponding relationships between voltage values and fault resistance values may be preset to obtain a specific ground resistance value.
The calculation process of the preset correspondence table between the voltage value and the fault resistance value is explained below with reference to fig. 5:
for the situation that the positive direct current bus has an insulation fault, firstly, the resistance value of the first switching subunit 301 and the resistance value of the second switching subunit 302 are controlled to be the same, and are both the fifth resistance values, at this time, the detection unit 202 measures the leakage current Ia1 and the leakage voltage Ua1 of the direct current bus, and the ground resistance Ra1 of the positive direct current bus is obtained according to the ohm law, that is, ra1= Ua1/Ia1;
after the first detection is completed, the resistance value of the first switching subunit 301 and the resistance value of the second switching subunit 302 are switched to be a sixth resistance value, at this time, the detection unit 202 detects the leakage current Ia2 and the leakage voltage Ua2 of the direct current bus, and the ground resistance Ra2 of the positive direct current bus is obtained according to the ohm law, that is, ra2= Ua2/Ia2.
And manufacturing a corresponding relation table of the voltage value of the positive direct current bus and the fault resistance value according to the voltage value measured each time and the resistance value obtained by calculation.
Similarly, for the situation that the negative dc bus has an insulation fault, the resistances of the first switching subunit 301 and the second switching subunit 302 are controlled to be a fifth resistance, at this time, the detection unit 202 measures the leakage current Ib1 and the leakage voltage Ub1 of the negative dc bus, and the ground resistance Rb1 of the negative dc bus is obtained according to the ohm's law, that is, rb1= Ub1/Ib1;
after the first detection is finished, the resistance values of the first switching subunit 301 and the second switching subunit 302 are switched to a sixth resistance value, at this time, the detection unit 202 measures a leakage current Ib2 and a leakage voltage Ub2 of the negative direct current bus, and the ground resistance Rb2 of the negative direct current bus is obtained according to ohm's law, that is, rb2= Ub2/Ib2.
And according to the voltage value measured each time and the resistance value obtained by calculation, a corresponding relation table of the voltage value of the negative direct current bus and the fault resistance value is manufactured.
For the situation that both the positive and negative direct-current buses have an insulation fault, the first switching subunit 301 is controlled to be a first resistance value, the second switching subunit 302 is controlled to be a second resistance value, at this time, the detection unit 202 measures leakage current Ia3 and leakage voltage Ua3 of the positive direct-current bus, leakage current Ib3 and leakage voltage Ub3 of the negative direct-current bus, two binary linear equations Ia3= (Ua 3)/Rb 3- (Ua 3)/Ra 3 and Ib3= (Ub 3)/Ra 3- (Ub 3)/Rb 3 are obtained, known Ia3, ib3, ua3 and Ub3 are substituted, and the ground resistance Ra3 of the positive direct-current bus and the ground resistance Rb3 of the negative direct-current bus are obtained;
after the first detection is completed, the first switching subunit 301 is switched to the second resistance value, the second switching subunit 302 is switched to the first resistance value, and at this time, the detection unit 202 detects the leakage current Ia4 and the leakage voltage Ua4 of the positive dc bus, the leakage current Ib4 and the leakage voltage Ub4 of the negative dc bus, so as to obtain two linear equations Ia4= (Ua 4)/Rb 4- (Ua 4)/Ra 4 and Ib4= (Ub 4)/Ra 4- (Ub 4)/Rb 4, which are substituted into the known equations Ia4, ib4, ua4 and Ub4, and the ground resistance Ra 'of the positive dc bus and the ground resistance Rb' of the negative dc bus are obtained.
And according to the voltage value measured each time and the resistance value obtained by calculation, a corresponding relation table of the voltage value of the positive and negative direct current buses and the fault resistance value is manufactured.
In the above embodiment, the ground resistance Ra of the positive dc bus and the ground resistance Rb of the negative dc bus are not actually present resistance elements, but are formed by grounding the positive dc bus and the negative dc bus, and can be regarded as a ground insulation resistance having an infinite resistance value.
The utility model discloses can be for portable insulation fault detection device, have portable, the characteristics of convenient operation.
The embodiment of the utility model discloses an insulation fault detection device is applied to DC power supply system, and this system includes positive DC bus, burden DC bus and a plurality of load branch roads of being connected with positive DC bus and burden DC bus respectively, and the device includes: the device comprises a switching unit and a detection unit, wherein the detection unit comprises a current acquisition module and a voltage display module, the first end of the switching unit is connected with a positive direct-current bus, the second end of the switching unit is connected with a negative direct-current bus, the third end of the switching unit is grounded, and the detection unit is respectively connected with the positive direct-current bus and the negative direct-current bus of the direct-current power supply system; the switching unit is used for switching resistance values; the detection unit is used for detecting the leakage current value on the load branch circuit under the switching units with different resistance values, converting the leakage current value into a voltage value, so that detection personnel can obtain the resistance values of the corresponding multiple grounding resistors according to different resistance values switched by the switching units, different voltage values displayed by the voltage display module and a preset corresponding relation, and judge whether the load branch circuit has an insulation fault according to the obtained resistance values of the multiple grounding resistors. Because the embodiment of the utility model provides an in the switching unit have the resistance and switch the function, consequently can obtain a plurality of ground resistance resistances through predetermined corresponding relation under the switching unit of different resistances, further confirm ground resistance's resistance to improve insulation fault's detection precision, avoid because insulating detection device measurement accuracy does not enough lead to the risk that supervisory equipment can't report an emergency and ask for help or increased vigilance, in addition, the integrated back of assembling of above-mentioned unit, portable is favorable to the measurement personnel to operate.
Various modifications and alterations of this invention may be made by those skilled in the art without departing from the spirit and scope of this invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (10)
1. An insulation fault detection device, applied to a dc power supply system including a positive dc bus, a negative dc bus, and a plurality of load branches connected to the positive dc bus and the negative dc bus, respectively, the device comprising: a switching unit and a detection unit, wherein,
the first end of the switching unit is connected with a positive direct-current bus, the second end of the switching unit is connected with a negative direct-current bus, the third end of the switching unit is grounded, and the detection unit is respectively connected with the positive direct-current bus and the negative direct-current bus;
the switching unit has a resistance value switching function;
the detection unit is used for detecting the leakage current value on the load branch circuit under the switching units with different resistance values, converting the leakage current value into a voltage value, so that a detection person can obtain the resistance values of the grounding resistors according to the different resistance values of the switching unit, the voltage values and a preset corresponding relation, and judge whether the load branch circuit has an insulation fault according to the obtained resistance values of the grounding resistors.
2. The apparatus according to claim 1, wherein the switching unit comprises a first switching subunit and a second switching subunit, wherein,
the first end of the first switching subunit is connected with the positive direct-current bus, the second end of the first switching subunit is grounded, the first end of the second switching subunit is connected with the negative direct-current bus, and the second end of the second switching subunit is grounded.
3. The apparatus of claim 2, wherein the first switching subunit comprises a plurality of first resistors and a first switching component, wherein,
a first end of each first resistor is used as a first end of the first switching subunit, and a second end of each first resistor is connected with a first end of the first switch component; a second end of the first switch component is used as a second end of the first switching subunit;
the second switching subunit comprises a plurality of second resistors and a second switch component, wherein,
a first end of each second resistor is used as a first end of the second switching subunit, and a second end of each second resistor is connected with a first end of the second switch component; a second end of the second switch component is used as a second end of the second switching subunit;
the first switch component is used for switching the resistance value of the first switching subunit;
and the second switch component is used for switching the resistance value of the second switching subunit.
4. The apparatus of claim 3, wherein the number of the first resistors and the number of the second resistors are both two, and the two first resistors have different resistances and the two second resistors have different resistances.
5. The apparatus of claim 4, wherein the first switch assembly comprises a first switch and a second switch, wherein,
the first switch is connected with one first resistor in series, a first end after series connection is used as a first end of the first switching subunit, and a second end after series connection is used as a second end of the first switching subunit; the second switch is connected with the other first resistor in series, a first end after series connection is used as a first end of the first switching subunit, and a second end after series connection is used as a second end of the first switching subunit;
the second switch assembly includes a third switch and a fourth switch, wherein,
the third switch is connected with one second resistor in series, a first end after series connection is used as a first end of the second switching subunit, and a second end after series connection is used as a second end of the second switching subunit; and the fourth switch is connected with the other second resistor in series, a first end after series connection is used as a first end of the second switching subunit, and a second end after series connection is used as a second end of the second switching subunit.
6. The apparatus of claim 4, wherein the first switch component is a first single pole double throw switch, wherein,
a first end of the first single-pole double-throw switch is connected with a first end of one first resistor, a second end of the first single-pole double-throw switch is connected with a first end of the other first resistor, and a third end of the first single-pole double-throw switch is used as a second end of the first switching subunit; the second end of one first resistor is connected with the second end of the other first resistor to serve as the first end of the first switching subunit;
the second switch assembly is a second single pole double throw switch, wherein,
a first end of the second single-pole double-throw switch is connected with a first end of one of the second resistors, a second end of the second single-pole double-throw switch is connected with a first end of the other one of the second resistors, and a third end of the second single-pole double-throw switch is used as a second end of the second switching subunit; and the second end of one second resistor is connected with the second end of the other second resistor to serve as the first end of the second switching subunit.
7. The device as claimed in claim 2, wherein the first switching subunit is a sliding varistor, and/or
The second switching subunit is a sliding rheostat.
8. The apparatus of claim 1, wherein the detection unit comprises a current collection module and a voltage display module, wherein,
the power supply end of the current acquisition module is connected with an external power supply end, the output end of the current acquisition module is connected with the voltage display module, the first input end of the current acquisition module is connected with the positive direct-current bus, and the second input end of the current acquisition module is connected with the negative direct-current bus;
the current acquisition module is used for acquiring a leakage current value on the load branch, converting the leakage current value into a voltage signal and sending the voltage signal to the voltage display module;
and the voltage display module is used for displaying the voltage value corresponding to the leakage current according to the voltage signal.
9. The apparatus of claim 8, wherein the current collection module is a dc transmitter.
10. The apparatus of claim 8 or 9, wherein the voltage display module is a voltmeter.
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