A kind of high impedance high-temperature stability high-voltage bleeder
Technical field
The present invention relates to a kind of high-voltage bleeder that is mainly used in electric system electrical device field, be specifically related to a kind of high impedance high-temperature stability high-voltage bleeder.
Background technology
Usually need to measure the ac high voltage of volts up to ten thousand in the power industry.The resistance-type high-voltage bleeder is a kind of high-tension measurement device, high voltage can be dwindled according to fixed proportion, to measure.Its principle as shown in Figure 1, U wherein
0Be tested high pressure, U
1Be the low-voltage signal of voltage divider output, high-voltage arm resistance R
2Much larger than low-voltage arm resistance R
1High-voltage arm resistor R wherein
2Owing to bear high voltage, need consideration to insulate, dispel the heat, prevent problems such as corona, volume generally need be done very greatly, and the while is disturbed it in order to prevent external environment, and the outside often needs to take shielding measure.Because the existence of high-voltage electric field, exist distributed capacitance between high-voltage arm resistor and the shield and between self each several part, these electric capacity come replacing representation by the space stray capacitance.The capacitance current that the existence of space stray capacitance causes causes the change of voltage divider output amplitude and phase place, and then causes the range error and the phase error of measurement result.And the size of space stray capacitance is relevant with the specific inductive capacity of insulating medium.Because the temperature coefficient of solid dielectric insulation specific inductive capacity is bigger, the capacity that changes the time space stray capacitance in environment temperature will cause bigger variation, thereby cause measurement result that bigger error has taken place.Will reduce this class error in the prior art, improving measuring accuracy has following several method:
First method: reduce the high-voltage arm resistance, weaken the shared ratio of space stray capacitance electric current with bigger current in resistance property, thereby weaken the influence that temperature variation causes changes in stray capacitances to cause, this is the solution of present main flow, it is very big that this method causes that high-voltage bleeder input impedance can not do, this has just strengthened the consumed power of voltage divider, cause that the high-voltage arm resistor heats up increases, further strengthened the capacitance current amplitude of variation of space stray capacitance, also strengthened the error that high-voltage arm resistor self-temperature causes simultaneously, and therefore need bigger area of dissipation, this has increased the volume of voltage divider.
Second method: patent [high value resistor, based on the voltage divider of this high value resistor] (application number: 200810112653.3, publication number: CN 101281809A, open day: 2008.10.08, applicant country:, provide a kind of high resistance resistor of realizing equivalent potential screen and China) based on the voltage divider scheme of this high resistance resistor.This scheme comprises resistor and the insulation course and the screen layer that set gradually from inside to outside around resistor, and wherein screen layer is a resistive film; Apply identical voltage respectively at the two ends of resistor and the two ends of screen layer.Adopt this technical scheme, the pressure drop on the high resistance resistor equates with pressure drop on the screen layer, does not therefore have voltage difference between the two, has also just solved the stray capacitance current problems, and some high resistance resistors connect the voltage divider that can form different proportion.This scheme, screen layer adopt resistor all to press scheme, and the screen layer resistor has increased excessive power drain, need to strengthen heat dispersion, raise to the influence of high-tension resistive precision to alleviate temperature.
The third method: patent [three phase electric energy measurement apparatus] (application number: 200910000667.0, publication number: CN 101458277A discloses day: 2009.06.17, applicant country: the method that China) another kind of realization high-voltage arm resistor equivalent potential screen is provided.Its equivalent potential screen structure is made of the conducting ring that a plurality of capacitances in series connect.This method is connected between high-field electrode and low-field electrode and is a plurality ofly waited the capacity voltage-dividing capacitors and constitute a plurality of equipotential planes, and the high-voltage arm resistor therefrom passes in the conducting ring, thereby reaches equipotential basically shield effectiveness.There is the potential risk of high-voltage breakdown short circuit in these capacitors, and quality requirements is handed over height, and need to increase the corresponding precautionary measures.
The 4th kind of method: patent [a kind of electrode structure of high-impedance broadband high-voltage bleeder] (application number: 201010034005.8, publication number: CN 101788583A, open day: 2010.07.28, applicant country: disclose a kind of electrode structure of high-impedance broadband high-voltage bleeder China), described electrode structure is to form the triangular cylinder structure by cylinder electrode through inclined cut, it obtains the effect that stray capacitance is cancelled out each other by high-pressure side guarded electrode and low-pressure side guarded electrode with respect to the special relative space relation of high-voltage arm resistor, thereby reduced the influence of stray capacitance, can improve the input impedance of voltage divider.
Above-mentioned several high-voltage bleeder scheme has a common characteristic, is exactly that the voltage divider agent structure is cylindrical, and the high-voltage arm resistor places on the axis of cylinder.This structure causes between high-field electrode and the low-field electrode distance longer, and this is favourable to anticorona and heat radiation.But on the other hand, can there be problem near high-field electrode or low-field electrode place temperature distributing disproportionation, the insulating medium change in dielectric constant was inconsistent near the temperature inequality caused high-field electrode and low-field electrode, influenced the distribution of space stray capacitance, and then having influenced the distribution of electric field, the result has influence on the voltage divider output accuracy.
Resistance divider has characteristics, if the high-voltage arm resistor is identical with the temperature coefficient of resistivity of low-voltage arm resistance device, if both working temperatures are identical, the error that temperature causes is cancelled out each other, voltage divider is exported not temperature influence, thereby have a higher temperature stability, therefore reduce the temperature stability that the temperature difference between high-voltage arm resistor and the low-voltage arm resistance device can improve voltage divider.Above-mentioned resistor also causes the low-voltage arm resistance device away from the high-voltage arm resistor by the axial array mode, thereby cause high-voltage arm resistor and the residing temperature environment of low-voltage arm resistance device to be difficult to be consistent, be difficult to offset the influence that the temperature difference produces the voltage divider output accuracy.
This class cylindrical shape axis symmetrical structure makes on the cross-sectional diameter direction in addition, it between resistor and the screen layer double insulation distance, this has increased the volume of high-voltage bleeder, is restricted sometimes when needs are integrated into some compact apparatus inside with high-voltage bleeder.
Summary of the invention
Technical matters to be solved by this invention is, a kind of high impedance high-temperature stability high-voltage bleeder is provided, and has the input impedance height, and low in energy consumption, temperature stability is good, and output accuracy is higher, the characteristics that volume is little.
Technical scheme of the present invention is as follows.
A kind of high impedance high-temperature stability high-voltage bleeder, the high-field electrode and the low-field electrode that comprise setting parallel to each other, the high-voltage arm resistor is installed between high-field electrode and low-field electrode, it is characterized in that: the high-voltage arm resistor is a chip resistor, it tilts to be positioned between high-field electrode and the low-field electrode, high-voltage arm resistor one side is near high-field electrode, and opposite side is near low-field electrode, and the angle between high-voltage arm resistor and the high and low pressure electrode is less than 30 degree; The high-voltage arm resistor connects high-field electrode near the lead-in wire of high-field electrode one side, draws near the low-field electrode near the lead-in wire of low-field electrode one side; The high-voltage arm resistor film of high-voltage arm resistor on the high and low pressure electrode with high and low pressure electrode vertical direction on the electrode plane scope that is projected in institute's projection within; Fill insulating medium between high-field electrode and the low-field electrode and around the high-voltage arm resistor.
The high-voltage arm resistor film of high-voltage arm resistor is installed on the substrate, and high-voltage arm resistor film both sides are connected with lead-in wire, and there is cover plate high-voltage arm resistor film top; Substrate and cover plate are the strip sheet, and both materials are identical with electric property.
Also comprise the low-voltage arm resistance device that is arranged at the low-field electrode outside, the resistive film of this low-voltage arm resistance device is identical with the resistivity of material temperature coefficient of high-voltage arm resistor film; Low-voltage arm resistance device one end lead-in wire is connected with the high-voltage arm resistor lead-in wire of close low-field electrode, and the other end is connected with low-field electrode.
The low-voltage arm resistance device is a chip resistor; It is near low-field electrode and parallel with low-field electrode; Low-voltage arm resistance has the radome that is connected with low-field electrode.
High-field electrode, low-field electrode and high-voltage arm resistor all are rectangular shapes; High-voltage arm resistor film on the high and low pressure electrode and the distance between the outer edge of the projection on the high and low pressure electrode vertical direction and the institute's projecting electrode outer edge be not less than half of distance between two electrodes.
In the high-field electrode and the low-field electrode outside, be connected with metallic shield respectively to the bending of comparative electrode direction; Described metallic shield and electrode of opposite insulation.
Described insulating medium is a silicon rubber.
Good effect of the present invention is: the first, the gradient basically identical that voltage distributes on the gradient of Electric Field Distribution and the resistor between electrode, each point and equipotential on every side on the resistor, weakened the influence of space stray capacitance and dielectric resistance to output accuracy, thereby when guaranteeing output accuracy, can design higher input impedance.For example the input impedance of 10kV high-voltage bleeder can be designed into 50M Ω, and dissipated power has only 2W like this, has saved energy consumption, has reduced the equipment work temperature.The second, two interelectrode distances have been shortened, and fill insulating medium of the same race, reduce the influence that the different parts temperature difference causes, thereby obtained higher temperature stability, and have lower temperature coefficient, still can keep higher measuring accuracy in the harsh out of doors working environment.Three, reduced the volume of high-voltage bleeder, 10 kilovolts of high-voltage bleeder volumes can be accomplished 120mm * 70 * 20mm, conveniently are integrated in other products.
Description of drawings
Fig. 1 is a resistance-type high-voltage bleeder circuit diagram.
Fig. 2 is the electric field potential-location diagram of high-voltage bleeder of the present invention.
Fig. 3 is the agent structure synoptic diagram of high-voltage bleeder of the present invention.
Fig. 4 is a high-voltage arm resistor structure synoptic diagram of the present invention.
Fig. 5 is the structural representation that the present invention has the high-voltage bleeder of symmetrical radome.
Fig. 6 is the structural representation that the present invention has low-voltage arm resistance device radome.
Fig. 7 is the high-voltage bleeder structural representation that the present invention has asymmetric radome.
Embodiment
The invention will be further described below in conjunction with the drawings and specific embodiments.
As shown in Figure 3, high-field electrode 1 and low-field electrode 2 are a pair of flat metal body that is parallel to each other; High-voltage arm resistor 3 is flat chip resistor; High-voltage arm resistor 3 tilts to be positioned between high-field electrode 1 and the low-field electrode 2, and a side is near high-field electrode 1, and opposite side is near low-field electrode 2, and the angle between high-voltage arm resistor 3 and the high and low pressure electrode is less than 30 degree.High-voltage arm resistor 3 connects high-field electrode 1 near the lead-in wire of high-field electrode 1 one sides, draws near low-field electrode 2 near the lead-in wire of low-field electrode 2 one sides.The high-voltage arm resistor film 31 of high-voltage arm resistance 3 is being projected within the electrode plane scope on the vertical direction on the high and low pressure electrode, that is to say, high-voltage arm resistor film 31 on the high and low pressure electrode with high and low pressure electrode vertical direction on the electrode plane scope that is projected in institute's projection within.Fill same dielectric medium 9 between high-field electrode 1 and the low-field electrode 2 and around the high-voltage arm resistor 3.
Wherein high-voltage arm resistor 3 is made up of substrate 32, high-voltage arm resistor film 31, first lead-in wire, 34, the second lead-in wires 35 and cover plate 33, as shown in Figure 4.Substrate 32 and cover plate 33 are the strip schistose texture, and their material is identical with electric property; Snakelike high-voltage arm resistor film 31 is arranged on the substrate 32; High-voltage arm resistor film 31 both sides are connected with first lead-in wire, 34 and second lead-in wire 35 respectively; There is cover plate 33 resistive film 31 tops.
The resistive film of low-voltage arm resistance device 4 is identical with the temperature coefficient of resistivity of high-voltage arm resistor film 31 materials of high-voltage arm resistor 3.Low-voltage arm resistance device 4 one ends lead-in wire is connected with high-voltage arm resistance 3 lead-in wires of close low-field electrode 2, and the other end is connected with low-field electrode 2.Low-voltage arm resistance device 4 is a chip resistor; Its position is in low-field electrode 2 outsides and near low-field electrode 2 and parallel with low-field electrode 2.
High-field electrode 1, low-field electrode 2 and high-voltage arm resistor 3 all are flat rectangular shapes, and high-voltage arm resistor film 31 is not less than distance between two electrodes half apart from the electrode plane outer edge at the outer edge of projection on the electrode plane vertical direction, that is to say, high-voltage arm resistor film 31 on the high and low pressure electrode and the distance between the outer edge of the projection on the high and low pressure electrode vertical direction and the institute's projecting electrode outer edge be not less than half of distance between two electrodes.Reaching the insulating medium 9 of filling around the high-voltage arm resistor 3 between high-field electrode 1 and the low-field electrode 2 is silicon rubber.
As shown in Figure 5, in the high-field electrode 1 and low-field electrode 2 outsides, also be connected with first metallic shield 11 and second metallic shield 12 to the bending of comparative electrode direction.Described metallic shield and electrode of opposite insulation.Low-voltage arm resistance device 4 has radome 10, and this radome 10 is connected with low-field electrode 2.
Voltage divider output terminal shown in Fig. 5-7 is first binding post 5, and voltage divider low pressure input end i.e. second binding post 6 connects the low pressure input, and the 3rd binding post 7 connects the high pressure input.
Provide several embodiment below to describe the present invention in detail.
First embodiment: as Fig. 4, shown in Figure 6, high-field electrode 1 and low-field electrode 2 respectively are of a size of 120mm * 70mm copper plate with one, and spacing 15mm is parallel to each other.High-voltage arm resistor 3 is of a size of the chip resistor of 100mm * 25mm for length and width, and resistance value is 50M Ω, and its substrate 32 all is to be made by the stupalith of identical physical dimension and material with cover plate 33.High-voltage arm resistor film 31 is coated on the ceramic substrate 32 by serpentine pattern equably; In the middle of substrate 32 and cover plate 33 are sealed in resistive film 31; High-voltage arm resistor 3 tilts to be positioned between high-field electrode 1 and the low-field electrode 2, and a side is near high-field electrode 1, and opposite side is near low-field electrode 2, and the geometric center of high-voltage arm resistor 3 overlaps with the geometric center of the rectangular parallelepiped of two electrodes formations.The projection of high-voltage arm resistor 3 on the electrode vertical direction is about electrode outer edge symmetry.High-voltage arm resistor 3 connects voltage divider high voltage input terminal 7 nearby with after high-field electrode 1 links to each other near first lead-in wire 34 of high-field electrode 1 one sides, is drawn out to the another side of low-field electrode 2 from close low-field electrode perforate 8 near second lead-in wire 35 of low-field electrode 2 one sides.
Low-voltage arm resistance device 4 adopts the resistive film material identical with high-voltage arm resistor 3 to make, and its resistance value is 6.8k Ω; Low-voltage arm resistance device 4 is installed being close to electrode near the position at low-field electrode 2 middle parts, low-voltage arm resistance device 4 one ends lead-in wire with draw from low-field electrode 2 tappings second go between and 35 be connected and be connected to first binding post 5.The other end of low-voltage arm resistance device 4 with connect second binding post 6 after low-field electrode 2 is connected.The low-voltage arm resistance device 4 outer radomes 10 that the red copper material is set are connected with low-field electrode 2 around the radome 10, have perforate that first binding post 5 is drawn on the radome 10.Curing molding is poured into a mould between high-field electrode 1 and the low-field electrode 2 and space around the high-voltage arm resistor 3 with electrically insulating silicone rubber.
Second embodiment: as shown in Figure 5, on the basis of the described voltage divider of first embodiment, in the high-field electrode 1 and low-field electrode 2 outsides, respectively there is one to be first metallic shield 11 and second metallic shield 12 of the red copper material of the cylindrical bending of axis, the space filled silicon rubber between first metallic shield 11 and second metallic shield 12 and high-field electrode 1 and low-field electrode 2 with the comparative electrode edge.Because first metallic shield 11 and second metallic shield 12 are when shielding is provided, less to the temperature stability influence of voltage divider spatially about two electrode symmetric offset spread.
The 3rd embodiment: as shown in Figure 7, on the basis of the described voltage divider of first embodiment, in low-field electrode 2 both sides, respectively there is one to be first metallic shield 11 and second metallic shield 12 of the cylindrical bending of axis, the space filled silicon rubber between first metallic shield 11 and second metallic shield 12 and high-field electrode 1 with high-field electrode 1 edge.Present embodiment since first metallic shield 11 and second metallic shield 12 spatially about two asymmetric arrangements of electrode, when shielding is provided, big than second embodiment to the temperature stability influence of voltage divider.
Further set forth the present invention below in conjunction with principle of work.
Principle of the present invention as shown in Figure 2, a pair of flat metal body electrode that is parallel to each other is to be full of uniform insulation medium 9 between high-field electrode 1 and the low-field electrode 2, applies voltage U between two electrodes
0, then the electric field between two electrodes is that a potential gradient is by the uniform electric field Es of high-field electrode 1 to low-field electrode 2 linear reductions
0, the electromotive force E of certain point in its electric field
1By this o'clock to the distributed capacitance two electrodes and insulating medium 9 electric resistance partial pressures than decision, and the resistance value of the capacity of distributed capacitance and insulating medium 9 resistance is all linearly proportional with distance under the identical prerequisite of dielectric material electric property, and promptly the electromotive force of each point is E in the electric field
1=d
1/ d
0* E
0If the resistor that resistance value is evenly distributed is positioned in this electric field obliquely, and two ends and two electrode equipotentials, put locational dividing potential drop U according to provable this resistor of geometrical principle on the resistive element length direction
1=l
1/ l
0* U
0=d
1/ d
0* E
0=E
1Therefore resistor at that point with on every side between the electric field electromotive force equate, the capacitance current of distributed capacitance on every side and the leakage current of insulator do not produce shunting to resistance, the electric current that does not then need to increase resistor reduces the influence of the capacitance current and the leakage current of distributed capacitance, thus the impedance of high-voltage arm resistor 3 can design very high.
Temperature is all influential to the specific inductive capacity and the resistivity of insulating medium 9.If certain o'clock is identical to the temperature of uniform insulation medium 9 between two electrodes in the electric field, then E
1=d
1/ d
0* E
0Relation is set up, and the influence of temperature factor is cancelled, and can obtain lower temperature coefficient.If but temperature difference, then E
1=d
1/ d
0* E
0No longer set up, will produce bigger temperature effect.Therefore the temperature difference that reduces between each point and two electrodes will reduce temperature effect effectively.Among the present invention because high-voltage arm resistor 3 is to tilt to be positioned between two electrodes with less angle, each point and two parallel pole close together on the resistance, the temperature difference between the two is less, so can obtain higher temperature stability.And the cylindrical structural in the existing technology, electrode is the two ends at resistor, and distance is far away, and the temperature difference between the two is difficult to reduce, and therefore is difficult to obtain higher temperature stability.
Resistor tilts to be positioned in the electric field, chip resistor is because the snakelike arrangement of resistive film, and the cross-section center line is parallel with electrode, voltage gradient on the resistor becomes dull trend in the longitudinal direction, the consistance of each point voltage and electric field potential on the resistive film can be improved, thereby capacitance current and leakage current can be reduced; And cylindrical resistor is because resistive film is circumferential arrangement, voltage gradient can not form dull trend on axis direction, each point voltage and each point electric field potential are inconsistent on the resistive film, has big electric potential difference, cause big capacitance current and leakage current, reduced temperature stability.
Carrier as resistive film, resistor substrate 32 is indispensable, but because the specific inductive capacity of the insulating medium 9 of filling between its specific inductive capacity and electrode is difficult to be consistent, it makes that relative two the interelectrode insulating mediums of resistor are inconsistent, to will having a negative impact of Electric Field Distribution.As above resistive film, installing a cover plate that material is identical with electric property symmetrically additional, make insulating medium 9 electric properties on resistor two sides be consistent, will offset this adverse effect.
In order to reduce the temperature error of 4 of high-voltage arm resistor 3 and low-voltage arm resistance devices, require two resistors to possess identical temperature coefficient of resistivity on the one hand, this needs both resistive films to select for use same material to make; Require to reduce two temperature difference between resistor on the other hand, this can be by also being designed to sheet with low-voltage arm resistance device 4, and be installed in parallel in low-field electrode 2 outsides, in the vertical projection scope of high-voltage arm resistor 3 at low-field electrode 2, the mode of being close to low-field electrode 2 obtains.Low-voltage arm resistance device 4 can increase metal screen layer and eliminate spatial interference, and metal screen layer connects low-field electrode 2.
The scope of the high and low pressure uniform electric field that electrode produces that is parallel to each other should could guarantee that like this high-voltage arm resistor 3 works in the uniform electric field greater than the fitting limit of high-voltage arm resistor 3, and above-mentioned relation is just set up.Therefore the outer edge of high-voltage arm resistor film 31 projections on the electrode plane vertical direction is good more apart from the big more effect of distance of electrode plane outer edge, is not less than half of distance between two electrodes in principle.Simultaneously, be subjected to space constraint, parallel pole can not infinitely extend, and this has just caused and has entered probabilistic spatial interference from the side.For weakening this interference,, be connected with metallic object to the bending of comparative electrode direction in the rectangle high-field electrode 1 and low-field electrode 2 outsides.This bending will weaken the uniformity coefficient of electric field between parallel pole, thereby reduce voltage divider temperature stability, this consideration of need compromising.On the other hand, if the bending of two lateral electrodes is symmetrical, then can offset a part of adverse effect.
Can fill multiple insulating medium between electrode, advantage such as wherein the silicon rubber insulation material is high pressure resistant because of having, climate adaptability is good is one and selects preferably.
It is worthy of note in addition, because the output impedance of high impedance high-temperature stability high-voltage bleeder of the present invention is also than higher, install one-level high input impedance voltage amplifier or voltage follower additional at first binding post 5, and itself and low-voltage arm resistance device 4 placed in the same shielding case, will improve the antijamming capability of voltage divider output signal effectively.