5th classes - english for electrical engineering
TRANSCRIPT
3/13/2011 Lecturer: Nguyen Xuan Tung
ENGLISH FOR ELECTRICAL ENGINEERING
Department of Electric Power System
Hanoi University of Science and Technology
Substations
Chapter 5
Overview
Basic terminology
2
General Introduction
Chapter 01: How to make an effective technical presentation
Chapter 02: Electrical Power System – An introduction
Chapter 03: Generation
Chapter 04: Transmission Lines
Chapter 05: Substations
Chapter 06: Distributions
Chapter 07: Consumptions
Chapter 08: Interconnected Power Systems
Chapter 09: System Protection & Control
Chapter 10: Other topics (if applicable)
Transformers
Circuit breakers
Air disconnect switches
Lightning arresters
Electrical buses
Capacitor banks
Reactors
Static VAR compensators
Control building
3
Major equipments in a substation
4
Transformer: Boost or Decrease voltage
5
Transformer - Details
2. Magnetic Core
7. Radiator
8. Windings
10. Load Tap Changer (LTC)
On-load Tap Changer (OLTC)
Air Cooling For Dry Type Transformers:
Air natural Type (A.N.)
Air Forced type (A.F.)
Cooling For Oil Immersed Transformers:
Oil Natural Air Natural Type (O.N.A.N.)
Oil Natural Air Forced Type (O.N.A.F.)
Oil Forced Air Natural Type (O.F.A.N.)
Oil Forced Air Forced Type (O.F.A.F.)
Oil immersed Water Cooling:
Oil Natural Water Forced (O.N.W.F.)
Oil Forced Water Forced (O.F.W.F.)
6
Transformer Cooling Methods
Air Cooling For Dry Type Transformers:
Air natural Type (A.N.): transformer is cooled by nature surrounding air.
Air Forced type (A.F.): air is forced on to the tank surface to increase the rate of heat dissipation.
Apply for dry type transformer
A dry type transformer is one which does not employ a liquid as a cooling or insulating medium.
7
Transformer Cooling Methods
8
Transformer Cooling Methods
Insulation requirements: tap points is placed at the low voltage end of the winding:
Near the star point in a star connected winding.
In delta connected windings: the tapings are usually at the center of the winding.
9
Tap Changing System
10
Tap Changing System
On-load Tap Changer Mechanism
Switching sequence
11
Tap Changing System
12
Tap Changer - Fitted
Tap changer
External control box
In an autotransformer:
A portions of the same winding act as both the primary and secondary: common winding.
An autotransformer:
Smaller size
Lighter & cheaper
However: does not provide electrical isolation.
13
Other type of transformer: Autotransformer
Bushings are used on transformers, circuit breakers... as connection points
Bushings connect outside conductors to conductors inside equipments
14
Transformer - Bushings
15
Transformer – Bushings CTs Location
Bushing CT
Switchgear: combination of electrical disconnects, fuses and/or circuit breakers used to isolate electrical equipment.
Switchgear: used both to:
De-energize equipment to allow work to be done
To clear faults downstream.
16
Circuit Breaker
Bulk Oil Circuit Breakers (BOCBs)
Minimum Oil Circuit Breakers (MOCBs)
Air Circuit Breakers (ACBs)
Air Blast Circuit Breakers (ABCBs)
SF6 Gas Circuit Breakers
Vacuum Circuit Breakers (VCBs)
17
Type of Circuit Breaker – Based on Interrupting Media
Bulk Oil Circuit Breakers (BOCBs)
Contacts is immersed in oil
Oil as insulation: live part & earthed metal tank
18
Type of Circuit Breaker – Based on Interrupting Media
Minimum Oil Circuit Breakers (MOCBs) (low oil)
Use oil as interrupting media
Interrupting unit in insulating chamber at live potential reduce requirement of oil
19
Type of Circuit Breaker – Based on Interrupting Media
Air Circuit Breakers (ACBs)
Contacts open & close in air at atmospheric pressure
Normally, apply for low voltage system only
20
Type of Circuit Breaker – Based on Interrupting Media
Air Blast Circuit Breakers (ABCBs)
21
Type of Circuit Breaker – Based on Interrupting Media
Air Blast Circuit Breakers (ABCBs)
22
Type of Circuit Breaker – Based on Interrupting Media
SF6 Gas Circuit Breakers
Contacts open & close in Sulphur Hexafluoride (SF6)
23
Type of Circuit Breaker – Based on Interrupting Media
Advantages over oil and air circuit breakers:
Due to property of SF6 : very short arcing time
Dielectric strength of SF6 gas is 2 to 3 times that of air can interrupt much larger currents.
Noiseless operation due to its closed gas circuit
No risk of fire as SF6 is non inflammable
Low maintenance cost, light foundation requirements and minimum auxiliary equipment
24
Type of Circuit Breaker – Based on Interrupting Media
Disadvantages:
SF6 breakers are costly due to high cost of SF6
SF6 Gas Circuit Breakers
25
Type of Circuit Breaker – Based on Interrupting Media
SF6 Gas Circuit Breakers
26
Type of Circuit Breaker – Based on Interrupting Media
Vacuum Circuit Breakers (VCBs)
Arc interruption takes place in vacuum
27
Type of Circuit Breaker – Based on Interrupting Media
Vacuum Circuit Breakers (VCBs)
Arc interruption takes place in vacuum
28
Type of Circuit Breaker – Based on Interrupting Media
Vacuum Circuit Breakers (VCBs)
Arc interruption takes place in vacuum
29
Type of Circuit Breaker – Based on Interrupting Media
Isolate or de-energize equipment for maintenance purposes (isolator)
Transfer load from one source to another in planned or emergency conditions
Provide visual openings for maintenance personnel
Being normally gang operated (or group operated)
Have low current interrupting ratings compared to circuit breaker
30
Air Disconnect Switches - Isolator
Vertical break type
31
Air Disconnect Switches - Types
Horizontal break type
32
Air Disconnect Switches - Types
Operating Mechanism
33
Air Disconnect Switches - Types
Designed to limit the L-G voltage in the event of lightning or other excessive transient voltages
34
Lightning Arrester
For substation
Designed to limit the L-G voltage in the event of lightning or other excessive transient voltages
35
Lightning Arrester
For lines
36