Description
Introduction
The LVQB(T)-35/66/110/220 type current transformer is an SF6 gas-insulated independent inverted structure current transformer independently developed by our factory based on reference to similar products at home and abroad. This product has advantages that oil-immersed instrument transformers cannot match: it uses high-insulation-strength SF6 gas as the insulating medium, resulting in excellent insulation performance, long service life, short production cycle, simplified process, oil-free operation, maintenance-free operation, and safer and more reliable operation. It can meet the high reliability requirements of modern power grids for power transmission and transformation equipment.
Characteristic of structure
The product consists of components such as the housing, explosion-proof diaphragm, active assembly, bushing, base, and density relay. The interior of the unit features shielding components designed to optimize the electric field distribution, while the secondary leads are terminated within a sealed junction box. The housing is available in two configurations: a three-way type and a bell-jar type.
The main insulation employs a coaxial cylindrical structure designed to generate a uniform electric field. The primary conductor rod and the secondary shielding collectively form this coaxial cylindrical, uniform electric field. To adjust the current ratio, either a series-parallel connection scheme for the primary winding or a purely parallel connection scheme may be utilized; in both cases, all specific transformation ratios are derived via taps on the secondary winding.
An explosion-proof diaphragm is installed on the upper section of the housing. While the internal insulation of this SF6 gas-insulated instrument transformer boasts exceptionally high reliability—making the occurrence of internal insulation breakdown arcs highly improbable under normal operating conditions—an explosion-proof diaphragm has been specifically incorporated as a safety precaution to mitigate the potential risks associated with internal arcing caused by unforeseen or accidental factors. External Insulation Bushing: For products rated at 220 kV and below, the external insulation utilizes either high-strength porcelain bushings or hollow composite bushings made of high-temperature vulcanized silicone rubber, capable of withstanding a rated pressure of 1.6 MPa (with a burst pressure exceeding 4.0 MPa).
Technical data
(1)Altitude: notexceed2000m(theones exceed 2000m shall be designed separately)(2)Ambienttemperature: -40°C~+50°C. dailymeantemperature not exceeds 30°C(3)Max monthly mean relative humidity: 90%(4)10minmaxaveragewind velocity:35m/s(5)Maxice coatingthickneSS: 10mm
(6)Class of pollution: III、 V Class
2. Maxvoltage of equipment: 40.5/72.5/126/252kV
3. Rated frequency: 50Hz
4. Rated P rjmarycu rrent: 300-4000A
5. Rated seconda ryCUrrent: 1Aor5A
6. Secondary combination: 0.2, 0.2S, 0.5, 0.5S, 5P, TPY, TPS Class
tombination at random
7. Rated Output: 0.2 class, 0.2S class, 0.5 class, 0.5S class, 5P class:
20-60VA TPYclass: 10-200
8. ACCUracylimltfactor:20-40
9. Instrumentseourityfactor: ≤5
10. ACCIJ racylimit conditi on of class TPY;
11. Rated insulating level: cu rrent transformer of 35kV;Currenttransformerof66kV: 72.5/140/325kVCurrenttransformerof 110kV: 126/200/480kVCurrent transformer of 220kV: 252, 395, 950kV12. Short-timethermal cu rrent: 50-63kA, 3S13. Rated peakwithstand current: 125-160kA(peak)14. Withstand voltagelevel under zero gauge pressu re: 1 3times of max working
voltage of equipment
15 Partial dischargelevel: 1.2timesofmaxworking voltageof equipment ≤5pC
16 Annual gas leakage rate: ≤0.5%
17 WatercontentofSF6 gas: ≤150x10-6(V/V)
18 Radiolnterferencelevel: 1.1 times ofmax working voltage of equipment radio
interference voltage≤500 uV
19 Specificcreepage distance of externalinsulation: 25mm/kV or 31mm/kv20 Static bearing load of primary terminal: 2000N-6000N21 Max total mass of product: cutrent transformer of 35kV: 450kg (thereinto mass
of SF6 gas is 4kg)
Currenttransformerof66kV: 500kg(thereintomassofSF6gasis5kg)
CurrenttransformerofllOkV: 600kg(thereintomassofSFsgasis7kg)
Currenttrensfomerof220kV: 1400kg(thereintomassofSF6gasie23kg)
