CN103354180A - No-load tapping-off switch for underground transformer - Google Patents

Abstract

Provided is a no-load tapping-off switch for an underground transformer. The no-load tapping-off switch comprises an insulation seat; more than two tapping-off columns are arranged in the insulation seat; each tapping-off column is composed of a conductor; the two ends of each tapping-off column extend to the outside of the two end faces of the insulation seat respectively; any one end face of the insulation seat is provided with an insulation enclosure wall; and the insulation enclosure walls isolate the end portions of any two neighboring tapping-off columns. The insulation enclosure wall structures are arranged in an interval manner on the tapping-off switch so that creepage distance is increased and alternate dielectric strength is ensured, accordingly the size is reduced and the no-load tapping-off switch provided by the invention is suitable for the underground transformer. Contacts are distributed in a shape of a circle so that the structure is compact, and the inter-contact insulation strength is ensured under the condition that the size is reduced. Besides, in the tapping-off columns, the static contacts and the dynamic contacts are connected in a sleeving manner of a circular column and a cylinder pipe so that the contact area is increased, the contact resistance is reduced, no compaction springs are needed, and the long-term operation is reliable.

Description

The no-load tapping switch that is used for underground transformer

Technical field:

The present invention relates to electricity field, relate in particular to transformer, particularly a kind of no-load tapping switch for underground transformer.

Background technology:

Shunting switch is a pith of transformer, is the contact system that possesses higher mechanical strength and heat resistance.In the prior art, the version of shunting switch is cydariform, cage type, bar shaped, dish type or wedge shape etc., and its overall dimension is all larger, is not suitable for underground transformer.And if be installed to underground transformer after will having the shunting switch reduced volume now, then alternate creepage distance is shortened, thereby has weakened phase insulation intensity, causes fault to occur.

Summary of the invention:

The object of the present invention is to provide a kind of no-load tapping switch for underground transformer, described this no-load tapping switch for underground transformer will solve the technical problem that the prior art shunting switch is difficult to be applied to underground transformer.

This no-load tapping switch for underground transformer of the present invention, comprise an insulating base, be provided with plural tap post in the described insulating base, any one described tap post consists of by conductor, the tap post all is parallel to the axial of insulating base, wherein, the two ends of described tap post extend to outside two end faces of insulating base separately, all be provided with separately the insulation enclosure wall in any one end face of insulating base, described insulation enclosure wall is isolated the end of two tap posts of arbitrary neighborhood mutually.

Further, any one described tap post all comprises a fixed contact and a moving contact separately, and described fixed contact is connected cylinder to be connected the socket form with cylindrical tube to connect with moving contact.

Further, the end face of insulating base is rounded, and the tap post is distributed in the end face of insulating base along a circumferencial direction.

Further, an end of insulating base is provided with a tapping plate, and described tapping plate adopts flange arrangement.

Further, be provided with vertically a screwed pipe on the tapping plate, be provided with a spiral cover on the described screwed pipe, the place, axle center of described spiral cover is provided with aperture, is provided with a block in the described aperture.

Further, can add proportion in the described screwed pipe greater than the iknsulating liquid of water.

Operation principle of the present invention is: the tap post is made of conductor, connects phase line, and alternate employing insulation fence structure has increased creepage distance, can guarantee phase insulation intensity.Contact adopts circular distribution, and compact conformation under the prerequisite of reduced volume, is guaranteed dielectric strength between contact.In the tap post, fixed contact is connected cylinder to be connected the socket form with cylindrical tube to connect with moving contact, and contact-making surface increases, and can reduce contact resistance, need not adopt holddown spring.

The present invention compared with prior art, its effect is actively and significantly.The present invention has increased creepage distance at the alternate insulation fence structure that is provided with of shunting switch, can guarantee phase insulation intensity.Thereby can reduce volume, make the present invention be applicable to underground transformer.Contact adopts circular distribution, and compact conformation under the prerequisite of reduced volume, is guaranteed dielectric strength between contact.In addition, in the tap post, fixed contact is connected cylinder to be connected the socket form with cylindrical tube to connect with moving contact, and contact-making surface increases, and can reduce contact resistance, need not adopt holddown spring, and long-time running is reliable.

Description of drawings:

Fig. 1 is the structural representation of the no-load tapping switch for underground transformer of the present invention.

Fig. 2 is breakdown field strength and the volume relationship schematic diagram of transformer oil in the uniform electric field of an embodiment of the no-load tapping switch for underground transformer of the present invention.

Embodiment:

Embodiment 1:

As shown in Figure 1, no-load tapping switch for underground transformer of the present invention, comprise an insulating base 5, be provided with plural tap post 4 in the described insulating base 5, any one described tap post 4 consists of by conductor, tap post 4 all is parallel to the axial of insulating base 5, wherein, the two ends of described tap post 4 extend to outside two end faces of insulating base 5 separately, all be provided with separately insulation enclosure wall 6 in any one end face of insulating base 5, described insulation enclosure wall 6 is isolated the end of two tap posts 4 of arbitrary neighborhood mutually.

Further, any one described tap post 4 all comprises a fixed contact and a moving contact separately, and described fixed contact is connected cylinder to be connected the socket form with cylindrical tube to connect with moving contact.

Further, the end face of insulating base 5 is rounded, and tap post 4 is distributed in the end face of insulating base 5 along a circumferencial direction.

Further, an end of insulating base 5 is provided with a tapping plate 7, and described tapping plate 7 adopts flange arrangement.

Further, be provided with vertically a screwed pipe on the tapping plate 7, be provided with a spiral cover 2 on the described screwed pipe, the place, axle center of described spiral cover is provided with aperture, is provided with a block 1 in the described aperture.

Further, can add proportion in the described screwed pipe greater than the iknsulating liquid of water.

The operation principle of present embodiment is: tap post 4 is made of conductor, connects phase line, and alternate employing insulation enclosure wall 6 structures have increased creepage distance, can guarantee phase insulation intensity.Contact adopts circular distribution, and compact conformation under the prerequisite of reduced volume, is guaranteed dielectric strength between contact.In the tap post 4, fixed contact is connected cylinder to be connected the socket form with cylindrical tube to connect with moving contact, and contact-making surface increases, and can reduce contact resistance, need not adopt holddown spring.

In the present embodiment, shunting switch can bear the lightning impulse voltage of underground transformer, all-wave is arranged and cut two kinds in ripple, and the voltage that has just entered transformer when lightning impulse voltage is distributed as capacitance profile, and its transient voltage is

$U_K{I}_K=0=\frac{\mathrm{UoSin\α}(1-X)}{\sin \∝l}$

Wherein

The electric field strength of X:

$E_X-\frac{\mathrm{duxx}}{\mathrm{dx}}=u_0\mathrm{\α}{E}_x=-\frac{{\mathrm{dU}}_{\mathrm{XX}}}{d_x}=U_0\mathrm{\α}\frac{\cosh \mathrm{\α}(1-x)}{\sinh \mathrm{\αl}}$

When the point insulating of center: $U_X{1}_t=O_T=\frac{\cosh \mathrm{\α}(1-x)}{\sinh \mathrm{\αl}}$

X is electric field strength $\mathrm{Ex}=\frac{-{\mathrm{duxx}}^o}{\mathrm{dx}}=\mathrm{Uo\α}\frac{\sinh \mathrm{\α}(1-x)}{\cosh \mathrm{\αl}}$

The electric field strength of head end $\mathrm{Ex}=(-\frac{\mathrm{\αoxxo}}{\mathrm{dx}})x=o=\mathrm{Vo\α}+\mathrm{on\αl}$

The position generally between the 5-30 during as α l=3, has

$\tanh \∂l=\coth \∂l=1$

After the same day, limit for length's rectangular wave entered transformer, when neutral point insulating, U _X1 _T=∞=ν ₀

$f_1\left(x\right)=\mathrm{Uxlxot}-\mathrm{Uxlx}=\∞=\mathrm{Uo}[\frac{\sinh \mathrm{\α}(1-x)}{\sinh \mathrm{\αl}}-(1-\frac{x}{l})]$

$f_2\left(x\right)=\mathrm{Uxlxot}-\mathrm{Uxlx}=\∞=\mathrm{Uo}[\frac{\cosh \mathrm{\α}(1-x)}{\cosh \mathrm{\αl}}-1]$

Utilize the Fourier series can be with f ₁(x) and f ₂(x) divide Jie to be a series of space harmonics

When neutral point insulating, other harmonic wave 1/4 multiple ripples of 1/4 ripple mouth of minute Jie's gained, when all stack result must satisfy x=0, f ₂(x)=0 f and during x=1 ₂(x) be maximum=1

According to Fourier series

f ₁(x)＝ΣA _ksinμ _kx

f ₂(x)＝ΣA _ksinμ _kx

In the formula

K=1,2,3---are namely

(all-wave)---

${{\mathrm{\υ}}_K}^{1}X=\frac{(2K-1)\mathrm{\π}}{2}\frac{X}{l},$ K=1,2,3 namely

(all-wave)---

Each harmonic amplitude Ak and Ak ¹Available Fourier series is asked for

$A_k=\frac{2}{l}{\∫}_0{f}_1\left(x\right)\sin {\mathrm{\μ}}_k\mathrm{xdx}$

${A_k}^1=\frac{2}{l}{\∫}_0{f}_2\left(x\right)\sin {{\mathrm{\μ}}_k}^1\mathrm{xdx}$

Since comprise inductance and electric capacity in the transformer equivalent circuit, so transients has concussion, electricity

Distribution is the function in space, is again the function of time, and its expression formula is as follows:

When neutrality is insulation

$u(x,\mathrm{\π})=u_0+u_0\∞{\mathrm{Ak}}^1\sin {\mathrm{\μk}}^1\×\cos {\mathrm{\ω}}^1\mathrm{kt}=u_0\{1-\frac{4}{\mathrm{\π}}\mathrm{\Σ}\frac{\frac{\sin (2k-1)\mathrm{\π}\×\cos {\mathrm{\ωk}}^{1}t}{l}}{(2k-1)[1+\frac{k}{c}{\left[\frac{(2k-1)\mathrm{\π}}{2}\right]}^2]}\}$

${\mathrm{\ωk}}^1=\frac{\frac{2k-1}{2}\mathrm{\π}}{\sqrt{\mathrm{Lc}[1+{\left(\frac{k-1}{2}\mathrm{\π}\right)}^2]}}$

Shunting switch insulation is comprised of epoxy and oil clearance two parts, the formula calculating that electrician's research provides of entirely reviving of the available Soviet Union of the relation of its puncture voltage and insulation distance:

A insulation distance (mm) wherein, U _BminBe the all-wave minimum break-down voltage of pure oil clearance at uniform electric field F, when ring is 1:3 with oil clearance solidity ratio, the anti-I of dielectric field is than for 2:1 the time, then=calculating the electric field that refers to divides namely and be respectively:

$E_X=\frac{{\mathrm{\ϵ}}_{y}U}{{\mathrm{\ϵ}}_z{d}_y+{\mathrm{\ϵ}}_y{d}_E}$ Mv/m

$E_y=\frac{{\mathrm{\ϵ}}_{E}0}{{\mathrm{\ϵ}}_z{d}_y+{\mathrm{\ϵ}}_y{d}_E}$ Mv/m

In the formula: U is test voltage Mv, ε _zE _yBe respectively epoxy resin, by middle electric field strength Mv/M _jε _zε _yBe respectively epoxy resin, coefficient among relative Jie of oil, d is insulation distance mm.

Fig. 2 has represented among the embodiment relation of the breakdown field strength of transformer oil and volume in the uniform electric field.

Claims (6)

1. no-load tapping switch that is used for underground transformer, comprise an insulating base, be provided with plural tap post in the described insulating base, any one described tap post consists of by conductor, the tap post all is parallel to the axial of insulating base, it is characterized in that: the two ends of described tap post extend to outside two end faces of insulating base separately, all be provided with separately the insulation enclosure wall in any one end face of insulating base, described insulation enclosure wall is isolated the end of two tap posts of arbitrary neighborhood mutually.

2. the no-load tapping switch for underground transformer as claimed in claim 1, it is characterized in that: any one described tap post all comprises a fixed contact and a moving contact separately, and described fixed contact is connected cylinder to be connected the socket form with cylindrical tube to connect with moving contact.

3. the no-load tapping switch for underground transformer as claimed in claim 1, it is characterized in that: the end face of insulating base is rounded, and the tap post is distributed in the end face of insulating base along a circumferencial direction.

4. the no-load tapping switch for underground transformer as claimed in claim 1, it is characterized in that: an end of insulating base is provided with a tapping plate, and described tapping plate adopts flange arrangement.

5. the no-load tapping switch for underground transformer as claimed in claim 1, it is characterized in that: be provided with vertically a screwed pipe on the tapping plate, be provided with a spiral cover on the described screwed pipe, the place, axle center of described spiral cover is provided with aperture, is provided with a block in the described aperture.

6. the no-load tapping switch for underground transformer as claimed in claim 1 is characterized in that: can add proportion in the described screwed pipe greater than the iknsulating liquid of water.

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