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Oil-Immersed Current Transformers_LB_.pdf

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\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n \n1. Oil-Immersed Current Transformers(LB)

2. Instruction:

LB-110, this current transformer has a hermetical structure, each sealing surface has been hermetically sealed by oil resistant rubbers. In order to ensure each of connection fastened well and not to make the gaskets compressed too much, all parts of the equipment are sealed up limitedly. The equipment is mainly comprised of metallic bellows, device body, porcelain bushing, oil tank, primary winding terminal plate and secondary winding terminal box. The primary winding forms chain type, using the insulation structure of oilpaper. The transformation of current ratio can be carried out by the external implementation of series and parallel connections for primary winding terminal plate, or by the exchanged connection for secondary winding terminals, that is, measuring winding and protective winding can be tapped. Secondary windings go around the Ring Core, set in the bottom of primary winding and placed in the oil tank; secondary winding terminal box is located in the front of oil tank, oil valve for draining is located at the bottom of oil tank. Metallic bellows is installed at the top of the product, which can play a role in volume compensation when the oil temperature varies, and isolate effectively the transformer oil from the atmosphere, so that prevent the ageing of transformer oil. Metallic bellows (PB type) is made of a certain number of expansion joints welded in series, which owns the advantages of displaying direct for the oil level and reflecting sensitively for the pressure. Outline dimensions drawing and structure shown in Figure 1. 

3. Service Conditions

a. Outdoor

b. Ambient air temperature: -40 ~ +40℃(average value of the ambient air temperature does    not exceed 30℃ measured during a period of 24h).

c. Altitude ≤1000m(this is the routine requirement, if there is any different requirement, we can  provide the products with 2000m, 3000m, 4000m or 5000m altitude according to the clients’ requirements).

d. Application: There have to be no gas that may seriously affect the insulation and conductive ability of electric equipments, steam, ash, salt, chemical deposit, pollution and corrosive or explosive material

e. The average value of the relative humidity does not exceed 95% at 25℃ measured during a period of one month.

f. Max. wind speed ≤34m/s

g. Earthquake intensity ≤ 7 degree. 

4. Main technical Parameters

Rated frequency:50 or 60Hz

Rated primary current:50 ~ 4000A

Rated secondary current:1 or 5A

Rated output：10~60VA

Instrument security factor(FS) :5 or 10

Accuracy limit factor:10, 15, 20, 30, 40, 50 or 60

Accuracy class for metering cores: 0.2, 0.2S, 0.5, 0.5S, 1 or 0.3, 0.6, 1.2

Accuracy class for protective cores: 5P, 10P, PR, PX, TPS, TPX, TPY, TPZ or C10, C20, C50, C100, C200, C400, C800

Rated short-time thermal current: ≤40kA/3s

Rated dynamic current: ≤100kA

Creepage distance:31mm/kV

Arcing distance and creepage distance of outer insulation please see table 1.

Table 1

Rated voltage(kV)

Arcing distance(mm)

Creepage Distance (mm)

35

≥470

≥1256

66

≥720

≥2248

110

≥1350

≥3906

132

≥1500

≥4495

150

≥1710

≥5270

220

≥1975

≥7812

 

Insulation requirements for the primaries please see table 2.

Table 2

Rated voltage (kV)

35

66

110

132

150

220

power-frequency withstand voltage (r.m.s) (kV)

95

160

230

275

325

460

The wet test for the current transformer of power-frequency withstand (r.m.s) (kV)

95

160

230

275

325

460

Rated switching impulse withstand voltage (peak) (kV)

--

--

--

--

--

--

Rated lightning impulse withstand voltage (peak) (kV)

200

325

550

650

750

1050

chopped lightning impulse voltage (peak) (kV)

230

373

635

750

865

1208

power-frequency withstand voltage at the SF6 gas pressure 0MPa (kV)

30

54

95

109

128

190

Partial discharge level

prestressing performed voltage (r.m.s) (kV)

76

112

184

220

260

368

Test voltage 1.2Um or Um (kV)  PD≤10pC

49

87

126

145

170

252

Test voltage 1.2Um/ (kV)  PD≤5pC

28

50

87

100.5

118

174

 

Mechanical requirements for the primary terminals please see table 3.

Table 3

Rated voltage (kV)

35

66

110

132

150

220

Mechanical requirements (horizontal of two directions and vertical) (N)

Load Ⅰ

--

1250

2000

2000

2000

2500

Load Ⅱ

--

2500

3000

3000

3000

4000

Applied to the primary terminals with duration (s)

--

60

60

60

60

60

 5. Dimensions of the Current Transformers

Figure 1

1. Oil viewing window    2. Primary terminals         3. Porcelain isolator

4. Earthing Terminal      5. Secondary terminals box    6. Name plate

 

Table 4

Rated Voltage

A (mm)

B (mm)

C (mm)

D (mm)

E (mm)

35

584

1770

258

424

14

66

630

1800

410

630

18

110

654

2450

475

710

20

132

654

2750

475

710

20

150

654

3050

475

710

20

220

896

3715

520

880

24

Notes: There may be any change of the dimensions for the current transformers because of renewing, the clients must basis on the updated drawings.

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