CN203786256U - Low-frequency superposition type measuring circuit - Google Patents
Low-frequency superposition type measuring circuit Download PDFInfo
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- CN203786256U CN203786256U CN201420182237.1U CN201420182237U CN203786256U CN 203786256 U CN203786256 U CN 203786256U CN 201420182237 U CN201420182237 U CN 201420182237U CN 203786256 U CN203786256 U CN 203786256U
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- 238000000034 method Methods 0.000 claims description 30
- 238000012360 testing method Methods 0.000 claims description 20
- 239000003990 capacitor Substances 0.000 abstract description 17
- 238000012544 monitoring process Methods 0.000 abstract description 8
- 230000008030 elimination Effects 0.000 abstract 3
- 238000003379 elimination reaction Methods 0.000 abstract 3
- 238000001514 detection method Methods 0.000 abstract 1
- 238000003745 diagnosis Methods 0.000 abstract 1
- 238000009413 insulation Methods 0.000 description 18
- 230000015556 catabolic process Effects 0.000 description 7
- 238000006731 degradation reaction Methods 0.000 description 7
- 240000005572 Syzygium cordatum Species 0.000 description 5
- 235000006650 Syzygium cordatum Nutrition 0.000 description 5
- 230000000149 penetrating effect Effects 0.000 description 3
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- 238000011161 development Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000005065 mining Methods 0.000 description 2
- 230000000505 pernicious effect Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
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- 238000001914 filtration Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
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- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003449 preventive effect Effects 0.000 description 1
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Abstract
The utility model discloses a low-frequency superposition type measuring circuit comprising a cable to be measured, a low-frequency power source, an exciting transformer, an inductor, a first capacitor, a second capacitor, a band elimination filter, a current transformer, an ampere meter, a first relay and a second relay which are connected between the load and the bus of a substation grounding transformer. The low-frequency power source is connected to the primary side of the exciting transformer. The input end of the band elimination filter is connected with the connection end of inductor and the second capacitor and the connection end of the second capacitor and the first capacitor separately. The output end of the band elimination filter, the current transformer and the ampere meter are connected successively. Grounding wires on two ends of the cable to be measured are grounded through the first relay and the second relay in the one-to-one correspondence manner. According to the low-frequency superposition type measuring circuit, voltages are superimposed from the grounding wires of the cable to be measured, the detection is simple and convenient, the low-frequency superposition type measuring circuit is used in 35kV cable insulating online monitoring, and the diagnosis result has the advantage of high reliability.
Description
Technical field
The utility model relates to a kind of low frequency method of superposition measuring circuit.
Background technology
Cable is embedded in underground more, once break down, find very difficultly, not only wastes a large amount of human and material resources, and can cause loss of outage difficult to the appraisal.In the actual moving process of cable, find, most of cable fault, because deteriorated causing occurs cable insulation, causes that deteriorated reason is mainly current weigher, and its main deteriorated form is that shelf depreciation is deteriorated, electric branch is deteriorated and water tree degradation.
The quality of cable insulation is the key factor that affects cable security reliability service.In the past, the widely used preventive trial of China is to adopt the method that regularly has a power failure and test, and belongs to offline inspection.Yet along with the development of electric power supply, the classic method of this power failure test more and more can not adapt to the actual needs of electrical production and supply.Therefore study on-line monitoring of cable technology, can be in time to cable reasonably safeguard, inspect and change, to guaranteeing that cable reliability service has great importance.
In recent years, in order to ensure the safe operation of cable, China had also obtained certain development on cable insulation on-line monitoring technique.At present, the on-line monitoring technique of cable is a lot, and DC component method and DC superposition method are exactly one of method being wherein widely used.A little less than but the electric current that DC component method and DC superposition method record is atomic, is generally to receive and pacifies level, small interference will cause very large error, in order to overcome these weakness of DC component method and DC superposition method, has scholar to propose to adopt low frequency method of superposition.
Utility model content
The purpose of this utility model is in order to overcome the deficiencies in the prior art, a kind of low frequency method of superposition measuring circuit is provided, ground wire superimposed voltage from cable under test, detect simple and convenient, for 35kV cable insulation on-line monitoring, diagnostic result reliability is high, can not only detect the insulation degradation that connects water tree, and may detect the insulation degradation of non-penetrating water tree.
A kind of technical scheme that realizes above-mentioned purpose is: a kind of low frequency method of superposition measuring circuit, comprise the cable under test being connected between load and the bus of substation ground transformer, also comprise low-frequency power, exciting transformer, inductance, the first electric capacity, the second electric capacity, rejection filter, current transformer, reometer, the first relay and the second relay, wherein:
Described low-frequency power accesses the former limit of described exciting transformer;
One end of the secondary of described exciting transformer is connected with the ground wire of one end of described cable under test, the other end of the secondary of described exciting transformer is connected with one end of described the first electric capacity with one end of described inductance respectively, the other end of described inductance, described the second electric capacity are connected successively with the other end of described the first electric capacity, the end ground connection of joining of described the second electric capacity and described the first electric capacity;
The input end of described rejection filter holds with joining of described inductance and described the second electric capacity respectively and the end that joins of described the second electric capacity and described the first electric capacity is connected, and the output terminal of described rejection filter, current transformer and reometer are connected successively.
The ground wire at the two ends of described cable under test is correspondingly by the first relay and the second relay ground connection.
Above-mentioned a kind of low frequency method of superposition measuring circuit, wherein, described rejection filter is double-T shaped rejection filter.
Above-mentioned a kind of low frequency method of superposition measuring circuit, wherein, the low-frequency power that described low-frequency power is 7.5Hz.
Above-mentioned a kind of low frequency method of superposition measuring circuit, wherein, the inductance value of described inductance is 100H, and the electric capacity of described the first electric capacity is 50 μ F, and the electric capacity of described the second electric capacity is 50 μ F.
A kind of low frequency method of superposition measuring circuit of the present utility model beneficial effect is compared with prior art: from the ground wire superimposed voltage of cable under test, detect simple and convenient, for 35kV cable insulation on-line monitoring, diagnostic result reliability is high, can not only detect the insulation degradation that connects water tree, and may detect the insulation degradation that non-penetrating water is set, can judge online the insulating property of high-tension cable, can meet electric power and the industrial and mining enterprises testing requirement to cable insulation, provide in advance the deteriorated early warning information of cable, to prevent trouble before it happens, in advance defective cable is changed or processed, avoid the generation of pernicious ground connection and short trouble, accuracy is high.
Accompanying drawing explanation
Fig. 1 is the circuit diagram of a kind of low frequency method of superposition measuring circuit of the present utility model;
Fig. 2 is the circuit diagram of double-T shaped rejection filter in embodiment.
Embodiment
Utility model people of the present utility model is in order to understand the technical solution of the utility model better, below by embodiment particularly, and is described in detail by reference to the accompanying drawings:
Refer to Fig. 1, embodiment of the present utility model, a low frequency method of superposition measuring circuit, comprises the cable under test X, low-frequency power 3, exciting transformer 4, inductance L, the first capacitor C 1, the second capacitor C 2, rejection filter 5, current transformer 6, reometer 7, the first relay 8 and the second relay 9 that are connected between load 1 and the bus of substation ground transformer 2.
The former limit of low-frequency power 3 access exciting transformers 4; One end of the secondary of exciting transformer 4 is connected with the ground wire of one end of X cable under test, the other end of the secondary of exciting transformer 4 is connected with one end of the first capacitor C 1 with one end of inductance L respectively, the other end of inductance L, the second capacitor C 2 are connected successively with the other end of the first capacitor C 1, the end ground connection of joining of the second capacitor C 2 and the first capacitor C 1.
The input end of rejection filter 5 holds with joining of inductance L and the second capacitor C 2 respectively and the end that joins of the second capacitor C 2 and the first capacitor C 1 is connected, and the output terminal of rejection filter 5, current transformer 6 and reometer 7 are connected successively.
The ground wire at the two ends of cable under test X is correspondingly by the first relay 8 and the second relay 9 ground connection, the first relay 8 and the second relay 9 when not measuring in normally off, when measuring, in normally open, in the time of can preventing from measuring like this, the low-frequency ac voltage superposeing does not flow to the earth from the ground wire of cable, can guarantee the accuracy of measurement, improves diagnostic accuracy.
Preferably, refer to Fig. 2, rejection filter 5 is double-T shaped rejection filter.The low-frequency power that low-frequency power 3 is 7.5Hz, the inductance value of inductance L is 100H, and the electric capacity of the first capacitor C 1 is 50 μ F, and the electric capacity of the second capacitor C 2 is 50 μ F.
The principle of work of a kind of low frequency method of superposition measuring circuit of the present utility model: the ground wire through cable under test X is superimposed upon on cable under test X low-frequency power 3 by the low-frequency voltage of 7.5Hz, 20V by exciting transformer 4; The cable insulation layer signal of cable under test X is input current transformer 6 after rejection filter 5 filtering, be input to again reometer 7, cable insulation three-phase total current is flow through in reometer 7 demonstrations, according to the deterioration condition of the insulation course of the signal analysis cable under test X on reometer 7.
In sum, low frequency method of superposition measuring circuit of the present utility model, ground wire superimposed voltage from cable under test, detect simple and convenient, for 35kV cable insulation on-line monitoring, diagnostic result reliability is high, can not only detect the insulation degradation that connects water tree, and may detect the insulation degradation that non-penetrating water is set, can judge online the insulating property of high-tension cable, can meet electric power and the industrial and mining enterprises testing requirement to cable insulation, provide in advance the deteriorated early warning information of cable, to prevent trouble before it happens, in advance defective cable is changed or processed, avoid the generation of pernicious ground connection and short trouble, accuracy is high.Low frequency method of superposition measuring circuit of the present utility model is also applicable to the following cable insulation on-line monitoring of 35kV.
Those of ordinary skill in the art will be appreciated that, above embodiment is only for the utility model is described, and be not used as restriction of the present utility model, as long as within the scope of connotation of the present utility model, to the variation of the above embodiment, modification, all will drop within the scope of claims of the present utility model.
Claims (4)
1. a low frequency method of superposition measuring circuit, comprise the cable under test being connected between load and the bus of substation ground transformer, it is characterized in that, also comprise low-frequency power, exciting transformer, inductance, the first electric capacity, the second electric capacity, rejection filter, current transformer, reometer, the first relay and the second relay, wherein:
Described low-frequency power accesses the former limit of described exciting transformer;
One end of the secondary of described exciting transformer is connected with the ground wire of one end of described cable under test, the other end of the secondary of described exciting transformer is connected with one end of described the first electric capacity with one end of described inductance respectively, the other end of described inductance, described the second electric capacity are connected successively with the other end of described the first electric capacity, the end ground connection of joining of described the second electric capacity and described the first electric capacity;
The input end of described rejection filter holds with joining of described inductance and described the second electric capacity respectively and the end that joins of described the second electric capacity and described the first electric capacity is connected, and the output terminal of described rejection filter, current transformer and reometer are connected successively;
The ground wire at the two ends of described cable under test is correspondingly by described the first relay and described the second relay ground connection.
2. a kind of low frequency method of superposition measuring circuit according to claim 1, is characterized in that, described rejection filter is double-T shaped rejection filter.
3. a kind of low frequency method of superposition measuring circuit according to claim 1, is characterized in that the low-frequency power that described low-frequency power is 7.5Hz.
4. a kind of low frequency method of superposition measuring circuit according to claim 1, is characterized in that, the inductance value of described inductance is 100H, and the electric capacity of described the first electric capacity is 50 μ F, and the electric capacity of described the second electric capacity is 50 μ F.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420182237.1U CN203786256U (en) | 2014-04-15 | 2014-04-15 | Low-frequency superposition type measuring circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420182237.1U CN203786256U (en) | 2014-04-15 | 2014-04-15 | Low-frequency superposition type measuring circuit |
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| CN203786256U true CN203786256U (en) | 2014-08-20 |
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| CN201420182237.1U Expired - Lifetime CN203786256U (en) | 2014-04-15 | 2014-04-15 | Low-frequency superposition type measuring circuit |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104316838A (en) * | 2014-11-06 | 2015-01-28 | 国网上海市电力公司 | Direct current superposition method measurement circuit |
| CN109917238A (en) * | 2019-02-27 | 2019-06-21 | 江苏科技大学 | Cable for ship on-line insulation monitoring device and monitoring method |
-
2014
- 2014-04-15 CN CN201420182237.1U patent/CN203786256U/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104316838A (en) * | 2014-11-06 | 2015-01-28 | 国网上海市电力公司 | Direct current superposition method measurement circuit |
| CN109917238A (en) * | 2019-02-27 | 2019-06-21 | 江苏科技大学 | Cable for ship on-line insulation monitoring device and monitoring method |
| CN109917238B (en) * | 2019-02-27 | 2021-04-06 | 江苏科技大学 | Online insulation monitoring device and method for marine cable |
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Granted publication date: 20140820 |
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