Dual Winding Oil Immersed Distribution Transformer with On-Load Tap Changer

Feature

Description

Winding Configuration

Dual (two) windings – typically HV and LV – with no autotransformer connection, allowing galvanic isolation and flexible voltage ratios .

Voltage Regulation

On-load tap changer allows ±8 × 1.25% or wider regulation range on HV side, enabling automatic voltage control under load .

Tap Changer Design

Vacuum-type OLTC housed in a separate oil-filled compartment, isolated from the main tank oil to prevent contamination and simplify maintenance .

Cooling Method

Standard ONAN (Oil Natural Air Natural); ONAF or OFAF available for higher ratings or overload conditions .

Vector Group

Common groups include Dyn11, Yzn11, or YNd11, depending on grounding and system requirements .

Construction

Core-type design with copper windings, corrugated steel tank, and hermetically sealed structure for durability and reduced maintenance .

Control & Monitoring

Supports local and remote electrical operation, manual emergency operation, and automatic voltage regulation with voltage relay and overcurrent lockout .

Rated
Capacity

Voltage ratio
(KV)

Vector
Group

No-load
Loss

No-load
Current

Full-load
Loss

Impedance

(kVA)

HV

Tapping
Range

LV

(kW)

(%)

(kW)

(%)

6300

110
121

±8×
1.25%

6.3
6.6
10.5
11

YNd11

10

0.6

36

10.5

8000

12

0.6

45

10000

14.2

0.55

53

12500

16.8

0.55

63

16000

20.2

0.5

77

20000

24

0.5

93

25000

28.4

0.45

110

31500

33.8

0.45

133

40000

40.4

0.4

156

50000

47.8

0.4

194

63000

56.8

0.35

234

75000

63.4

0.35

278

90000

73.1

0.3

320

120000

91.2

0.3

397