electrical phase to phase clearance

8/11/2019 Electrical Phase to Phase Clearance

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Version 2

STANDARDS/MANUALS/

GUIDELINES FORSMALL HYDRO DEVELOPMENT

Electro-Mechanical Works

Selection of Switchyard Equipment for SHP(Including Power Transformer and Circuit Breaker)

Sponsor:

Ministry of New and Renewable EnergyGovt. of India

Lead Organization:

Alternate Hydro Energy CenterIndian Institute of Technology Roorkee

May 2011


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CONTENTS

Sl. No. Items Page No.

1.0

Section 1

Guide for Design of Outdoor Step up Sub-Station

And Selection of Equipment

INTRODUCTION 1

2.0 DESIGN REQUIREMENTS 1

2.1 General 1

2.2 Seismic Consideration 2

2.3 Basic Insulation Level and Insulation Co-ordination 2

2.4 Electrical Clearances for Installing Equipment in the Field 8

2.5 Insulators Creepage Distance 11

2.6 Insulator Type 12


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2.7

2.8

2.9

2.10

2.11

2.12

1.0

2.0

3.0

3.1

3.2

3.3

3.4

3.5

3.63.7

3.8

3.9

4.0

4.1

4.2

4.3

4.4

4.5

4.6

4.7

4.8

5.0

Switchyard Structures

GIS Substations

Power Line Carrier Equipment

Substation Auxiliary Facilities

Bus Bar Schemes

Inspection and Maintenance

ANNEXURE 1.1

ANNEXURE 1.2

Section 2

Selection of Switchyard Equipment

BUS BAR

CIRCUIT BREAKERS

ISOLATORS

Temperature Rise

Rating

Isolator Insulation

Arcing Horn & Arcing Contacts

Load Break Switches

Terminal ConnectorsInterlocks

Supporting Structures

Fire Extinguishing System

CURRENT TRANSFORMERS

Type and Rating

Details of Current Transformer

General Requirements

Terminal Connectors 33 kV and Above

Type of Mounting

Tests

External Insulation (12 kV & Above)

Fittings and Accessories (12 kV & Above)

POTENTIAL TRANSFORMER AND COUPLING VOLTAGE

TRANSFORMER

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15

16

17

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2323

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5.1

5.2

5.3

5.4

6.0

7.0

8.0

9.0

10.0

11.0

12.0

1.0

2.0

3.0

4.0

5.06.0

7.0

8.0

8.1

8.2

8.3

8.4

8.5

8.6

8.7

8.8

8.9

8.10

Type and Rating of Potential Transformer

Temperature Rise

11 kV Voltage Transformer

Coupling Voltage Transformer (36 kV & Above)

TRANSFORMERS

LIGHTNING ARRESTORS

EQUIPMENT FOR CUMMUNICATION, RELAYING AND TELE

METERING AND OFF-SITE CONTROL

AUXILIARIES

REPAIR / INSPECTION FACILITIES

PALE FENCING

SWITCHYARD LAYOUT

Section 3

Selection of Power Transformer

GENERAL

GENERATOR TRANSFORMERS

TRANSFORMER RATING

STANDARD RATING

COOLINGTEMPERATURE RISE, OVERLOAD CAPACITY AND

CONTINUOUS RATING

TRANSFORMER STUDIES

ELECTRICAL CHARACTERISTICS

Type of Transformer and Operating Conditions

Continuous Maximum Rating and Overloads

Voltage Ratio

Duty Under Fault Condition

Electrical Connections

Flux Density

Current Density

Short Circuit Strength

Frequency and System Voltage

Parallel Operation

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30

30

31

31

31

35

35

35

36

36

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8.11

8.12

9.

10.

11.

12.

13.

14.

15.

16.

17.

18.

19.

20.

21.

1.

2.

3.

3.1

3.2

3.3

3.4

4.

5.

6.

7.

Vibration and Noise

Basic Insulation Levels (BIL)

IMPEDANCE

TRANSFORMER EFFICIENCY

TERMINAL BUSHINGS

TANKS

PRESSURE RELIEF DEVICE

ANTI EARTHQUAKE CLAMPING DEVICE

FITTINGS AND ACCESSORIES

DIELECTRIC TESTS

ACCESSORIES

OIL CONTAINMENT AND FIRE PROTECTION SYSTEM

FACTORY AND FIELD TESTING

ERECTION, MAINTENANCE TESTING AND COMMISSIONING

TYPICAL TRANSFORMER RATING AND CHARACTERISTICS

ANNEXURE 3.1

ANNEXURE 3.2

ANNEXURE 3.3

ANNEXURE 3.4

Section 4

Selection of Circuit Breaker

INTRODUCTION

CLASSIFICATION

TYPE OF CIRCUIT BREAKER

Vacuum Circuit Breaker

Advantages and Disadvantages

Evaluation of SF6 and Vacuum Switching Technologies

Protection Classes for Switchgear Installation

RATED CHARACTERISTICS

STANDARD RATINGS OF CIRCUIT BREAKERS

CO-ORDINATION OF RATED VALUES

TESTS

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8.

8.1

8.2

8.3

8.4

8.5

FAULT CALCULATION

Staged Short Circuit Tests

Circuit Breaker Rating for Short Circuit Duty

Simplified Methods for Calculation Short Circuit Current

E/X Simplified method as per IEEE std. C37010-1999

Simplified Method

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AHEC/MNRE/SHP Standards/E&M Works- Guidelines for Selection of Switchyard SHP Station


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n

n

rr

r

n

n

rr

r

n

n

rr

r


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nn

C rrrEnn

rrr

nr

nr

n

n

rr

r


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a

Code

First Digit Degree of protection against contact

And ingress of foreign bodies

Second Digit Degree of protection against ingress

Of water

Supplementary Sealing material between code letter

floor, ceiling or wall

IP 4 3 B

Protection Class


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kAkV


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voltageoperating

voltageimumRated


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xx

x


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AC

DC

I

xI


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Vr is recovery voltage stated in terms of voltage between phases at service frequency

Vrc is recovery voltage component existing across the breaks of each pole.


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electrical phase to phase clearance

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