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GRID

January 2012

Current Transformer

From Definition to Manufacturing

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Agenda

1 Critical data for Current Transformer Design and Calculation

2 Standard Lead time

Current transformer From Definition to Manufacturing 2012-01-06

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Agenda

1 Critical data for Current Transformer Design and Calculation

2 Standard Lead time

RMC Export Plan 2011-12-08

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Critical data for Current Transformer Design and Calculation

Electrical Parameters and Site conditions

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Critical data for Current Transformer Design and Calculation

CT Type OSKF 170Head Size 1 Size 2 Size 3

Core Box 1 2 3

Insulator A B C D E F H I J

Electrical Parameters and Site conditionsCores definition is now needed to definte the right Core Box, Head and Insulator Size

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Critical data for Current Transformer Design and Calculation

Size of cores depend among

others on

Accuracy class & burden

Transformation ratios

Short circuit current

Size (and price) of CT depends on Size of core box holding the cores

Type of ratio changes

Misestimated requirements may

lead to unnecessary costs

Secondary Cores Definition

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Critical data for Current Transformer Design and Calculation

10 VA 5P20 20 VA 5P20 50 VA 5P20

Core cross section

Secondary core + winding

Secondary Cores Definition has direct impact on Cores Box, Head andInsulator size

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Critical data for Current Transformer Design and Calculation

2000/1 A

Vkp>240 Volts with Rct=5 ohms

Core cross section

Secondary core + winding

Impact due to Class X defintion and choice of Rct value

2000/1 A

Vkp>240 Volts with Rct=10 ohms

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Critical data for Current Transformer Design and Calculation

1600/1 A

Vkp>1600 Volts with Rct=4 ohms

Core cross section

Secondary core + winding

Impact due to Class X defintion and choice of Vkp value

1600/1 A

Vkp>800 Volts with Rct=4 ohms

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Critical data for Current Transformer Design and Calculation

Secondary Cores Definition

Core definition is not possible without Class X parameters Input

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Critical data for Current Transformer Design and Calculation

Secondary Cores Definition

For each Core withClass X :Vk, Io and Rct have tobe defined

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Agenda

1 Critical data for Current Transformer Design and Calculation

2 Standard Lead time and Manufacturing Process

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Standard Lead time and Manufacturing Process

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Standard Lead time and Manufacturing Process

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Standard Lead time and Manufacturing Process

Cores are placed in such a way

to make best possible use of the available space.

(Simulation)

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Standard Lead time and Manufacturing Process

Magnetic sheet secondary cores

design & manufacturing

Winding of secondaries

Mounting of secondary cores inan aluminum shell

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Standard Lead time and Manufacturing Process

Magnetic sheet secondary cores

design & manufacturing

Winding of secondaries

Mounting of secondary cores inan aluminum shell

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Standard Lead time and Manufacturing Process

Magnetic sheet secondary cores

design & manufacturing

Winding of secondaries

Mounting of secondary cores inan aluminum shell

High voltage insulation : paper

taping

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Standard Lead time and Manufacturing Process

Magnetic sheet secondary cores

design & manufacturing

Winding of secondaries

Mounting of secondary cores inan aluminum shell

High voltage insulation : paper

taping

Intermediate semi-conductive

screens

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Standard Lead time and Manufacturing Process

Magnetic sheet secondary cores

design & manufacturing

Winding of secondaries

Mounting of secondary cores inan aluminum shell

High voltage insulation : paper

taping

Intermediate semi-conductive

screens

More paper taping

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Standard Lead time and Manufacturing Process

Magnetic sheet secondary cores

design & manufacturing

Winding of secondaries

Mounting of secondary cores inan aluminum shell

High voltage insulation : paper

taping

Intermediate semi-conductive

screens

More paper taping

Final conductive screen

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Standard Lead time and Manufacturing Process

Assembling:

Porcelain mounting

Secondary terminal box

cablingPrimary winding assembly

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Standard Lead time and Manufacturing Process

Assembling:

Porcelain mounting

Secondary terminal box

cablingPrimary winding assembly

Treatment:

Heat (105 C)

Vacuum (0.1 mBar)

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Standard Lead time and Manufacturing Process

Assembling:

Porcelain mounting

Secondary terminal box

cablingPrimary winding assembly

Treatment:

Heat (105 C)

Vacuum (0.1 mBar)

Oil treatment:

Oil filling under vacuum

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Standard Lead time and Manufacturing Process

Top cover mounting

Final inspection

Routine tests:

Dielectric

Partial discharges

Accuracy

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GRID

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