CN2852483Y

CN2852483Y - Distribution transformer and lightning protection apparatus of low-voltage power station

Info

Publication number: CN2852483Y
Application number: CN 200520051758
Authority: CN
Inventors: 宋益平
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-08-25
Filing date: 2005-08-25
Publication date: 2006-12-27
Anticipated expiration: 2015-08-25

Abstract

The utility model relates to a distribution transformer and a lightning protection apparatus for low-voltage power stations. The existing distribution transformer which adopts a three-dimensional and integrated grounding distribution transformer and a low-voltage power station has the defect of high probability of damage by lightning stroke. The utility model comprises a distribution transformer, a grounding body and a grounding down lead, which are connected by adopting an over-voltage shunting method. The utility model can separately discharge to the ground to different directions and areas when the high-voltage side and the low-voltage side of the distribution transformer suffer from lightning stroke for ensuring the transformer to safely operate.

Description

Distribution transformer and low-voltage power supply station lightning protection device

Technical field: the utility model relates to a kind of lightning protection device of transformer, particularly relates to the lightning protection device at a kind of distribution transformer and low-voltage power supply station.

Background technology: transformer is that an application law of electromagnetic induction converts electric energy to magnetic energy, and magnetic energy converts electric energy to again, to realize the calutron of voltage transformation; When earth electrode has electric current to pass through, it is wandering to make hemisphere to the earth, square being directly proportional of sphere area and radius, so the hemisphere area increases rapidly along with earth electrode, therefore the electric resistance of soil of hemisphere area correspondence is also along with reducing rapidly away from earth electrode, during to 20 meters of earth electrode, the hemisphere area has reached 2500 square metres, and electric resistance of soil is little of ignoring.Beyond 20 meters of earth electrodes, because of resistance equals zero, electric current no longer produces voltage drop, that is: when electric current flowed into the earth by earth electrode, earth electrode had ceiling voltage, and when leaving earth electrode, voltage drop descends gradually, and during to 20 meters, voltage reduces to zero.

The spreading resistance of earth electrode and the resistance of earth connection and be earth resistance.Because the resistance of earth connection is generally very little, can ignore, therefore can think that the earth electrode spreading resistance is an earth resistance, so earth connection does not play the diffusing stream effect of ground connection.

For Y, the distribution transformer lightning protection method of YnO wiring adopts the high-pressure side arrester ground, neutral ground of low pressure winding and the transformer case ground connection ground connection that connects together, when high-pressure side three-phase afferent echo advances, the electric current of lightning arrester discharge produces a very big surge voltage and falls on earth resistance, this voltage drop makes earthing device and low pressure neutral point equipotential, major part is applied on the low pressure winding by center line for it, flow through lightning current again at the low pressure winding, because of electromagnetic induction to the high pressure winding, pass through no-load voltage ratio, produce very high induced voltage on the high pressure winding, because the high pressure winding is connected into the Y type, so maximum appears on the high pressure neutral point, be calculated as IR=35KV if produce voltage drop IR on the earth resistance with 5KA and 7 Ω, to the 10/0.4KV distribution transformer, its no-load voltage ratio is 25, then the surge voltage at high-pressure side winding two ends reaches 25 * 35KV=875KV, because the voltage of high pressure winding terminal is controlled by lightning arrester, so the 875KV high potential will be distributed on the high pressure winding fully, and the property point reaches maximum therein, causes the interlayer or the turn-to-turn insulation of near insulation of neutral point or high pressure winding breakdown.

No matter be the high-pressure side, or the low-pressure side afferent echo, all be owing to have lightning current to flow through in the low pressure winding, and induce high voltage and the transformer of breaking in the high pressure winding, therefore, and the lightning-arrest poor-performing of the distribution transformer that Y, Yno connect.

The utility model content:

The purpose of this utility model just provides a kind of anti-lightning strike effective; no matter be the high-pressure side; still the low-pressure side afferent echo can not produce high voltage, breaks transformer and can both play the lightning protection device of a kind of distribution transformer of fine anti-lightning-arrest effect to jumbo distribution transformer and cause.

The utility model is achieved like this: comprise lightning arrester, earth electrode, down conductor, adopt the overvoltage shunting to connect, high-voltage arrester is housed between distribution transformer high-tension fuse and the transformer, the high-voltage arrester down conductor is got beeline and is connected with earth electrode Rjd1 by transformer is other with going into, after linking together, distribution transformer neutral point and metal shell equipotential be connected with earth electrode Rjd2 by down conductor, the low pressure leading-out terminal of low-pressure side low voltage surge arrester and distribution transformer is installed, and its down conductor is connected with earth electrode Rjd3.

Three earth electrode Rjd1, Rjd2, Rjd3 adopt several vertical grounding electrodes to connect into linear pattern separately, three earth electrode R _Jd1, R _Jd2, R _Jd3Any two earth electrode tops between the shortest clear distance L 〉=20 meters, three junctor R _Jd1, R _Jd2, R _Jd360 °≤x of angle between any two earth electrode reverse extending lines≤120 °.

Down conductor respectively with earth electrode R _Jd1, R _Jd2, R _Jd3Ground distance implement with beeline.

Low voltage surge arrester adopts pressure-sensitive lightning arrester.

The utility model adopts said structure, distribution transformer is when if high-pressure side or low-pressure side are struck by lightning, lightning arrester discharges over the ground, and to leak into the overvoltage of being born in the earth distribution transformer insulation be the residual voltage of lightning arrester to huge lightning current, thereby reach insulation coordination, play fine shunting action, guarantee the safe and reliable operation at distribution transformer and low-voltage power supply station, simultaneously because organizing and implementing rationally are convenient in connection.

Figure of description:

Fig. 1 has Y now, the lightning-arrest wiring schematic diagram of YnO transformer.

Fig. 2 is the utility model Y, the shunting of the YnO transformer wiring schematic diagram of taking shelter from the thunder.

Fig. 3 is that each earth electrode of the utility model connects floor map.

Among the figure: earth electrode R _Jd1, R _Jd2, R _Jd34,4a, 4b are respectively three earth electrode R _Jd1, R _Jd2, R _Jd3Down conductor; 5,5a, 5b are respectively three earth electrode R _Jd1, R _Jd2, R _Jd3The ground connection tail end; 6,6a, 6b are respectively three earth electrode R _Jd1, R _Jd2, R _Jd3Ground connection top; 7. high-voltage arrester; 8. low voltage surge arrester; 9. transformer; 10. distribution transformer neutral point; 11. distribution transformer shell terminals.

Embodiment:

The lightning-arrest wiring schematic diagram of the shunting of the utility model Y, YnO transformer shown in Fig. 2,3, and three earth electrode R _Jd1, R _Jd2, R _Jd3Ground connection connects floor map, between distribution transformer high-tension fuse and transformer 9, adorn one group of high-voltage arrester 7, distribution transformer 9 near (change of double rod type platform) bury three earth electrode Rjd1 underground, Rjd2, Rjd3, earth electrode Rjd1 buries underground from high-voltage arrester 7 nearest electric pole orientation, high-voltage arrester down conductor 4 get short distance through and fall to being connected along this electric pole with earth electrode Rjd1, down conductor 4 is short more good more, earth electrode Rjd1 resistance value is set to≤10 Ω, at distribution transformer 9 low-voltage side outlet ends one group of low-pressure pressure-sensitive lightning arrester 8 is installed, the neutral line is not adorned lightning arrester, its lightning protection earthing downlead 4b falls along another electric pole, Rjd3 is connected with earth electrode, earth electrode Rjd3 resistance value is provided with≤10 Ω, between two electric poles, be driven underground fixing with a hollow insulated rod, after the neutral point 10 of distribution transformer and metal shell 11 link together, scurried insulating rod with insulation ground lead 4a is connected with earth electrode Rjd2 with going into, resistance value to the 9 earth electrode Rjd2 of the distribution transformer more than the 100KVA is≤4 Ω, then≤10 Ω that 100KVA is following.The distribution transformer neutral point is connected with the shell equipotential, and distribution transformer and earth electrode voltage drop zone isolate (change of platform-type platform) with electrical insulating material, and the reinforced insulation mechanical strength.Top 6,6a, 6b, the shortest clear distance L is more than or equal to 20 meters between the earth electrode top 6 of three earth electrode Rjd1, Rjd2, Rjd3,6a, the 6b, angle x maximum between any two earth electrodes between three earth electrode Rjd1, Rjd2, the Rjd3 is no more than 120 degree, minimum is 60 degree, also be to say between any two earth electrodes parallelly or overlapping to bury underground, change must have certain angle, this implements between three earth electrodes angle setting 120 degree each other, and three earth electrodes adopt several vertical grounding electrodes to connect into linear pattern separately respectively.

The utility model adopts the high and low side at distribution transformer to be equipped with lightning arrester, and when distribution transformer high-pressure side or low-pressure side were struck by lightning, lightning arrester discharged over the ground, has guaranteed the safe operation of distribution transformer and low-pressure electricity station thereof to greatest extent.

Claims

1, a kind of distribution transformer and low-voltage power supply station lightning protection device; comprise lightning arrester; earth electrode; down conductor; adopt the overvoltage shunting to connect; it is characterized in that: high-voltage arrester (7) is housed between distribution transformer high-tension fuse and the transformer, high-voltage arrester down conductor (4) get beeline by transformer other go into earth electrode R _Jd1Connect, distribution transformer neutral point (10) and metal shell (11) link together the back by down conductor (4a) and earth electrode R _Jd2Connect, low-pressure side low voltage surge arrester (8) is installed its down conductor (4b) and earth electrode R with the low pressure leading-out terminal of distribution transformer (9) _Jd3Connect.

2, distribution transformer according to claim 1 and low-voltage power supply station lightning protection device is characterized in that: three earth electrode R _Jd1, R _Jd2, R _Jd3Adopt vertical grounding electrode to connect into linear pattern separately, three earth electrode R _Jd1, R _Jd2, R _Jd3Any two earth electrode tops (6,6a, 6b) between the shortest clear distance L 〉=20 meters, three junctor R _Jd1, R _Jd2, R _Jd3Angle χ between any two earth electrode reverse extending lines is 60 °≤χ≤120 °.

3, distribution transformer according to claim 1 and low-voltage power supply station lightning protection device is characterized in that: down conductor (4,4a, 4b) respectively with earth electrode R _Jd1, R _Jd2, R _Jd3Ground distance implement with beeline.

4, distribution transformer according to claim 1 and low-voltage power supply station lightning protection device, it is characterized in that: low voltage surge arrester (8) adopts pressure-sensitive lightning arrester.