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INTRODUCTION
1.1 Overview
Now a day’s electricity has played a vital role for the economic development of the country as well as makes people’s life easy and comfortable, reliable, uninterrupted, safe and adequate power supply is a pre-requisite for the development of the country.
1.2 Broad Objective
The main objective of the report has been done to show the total working procedure of power transmission, distribution, substation operation, controlling and various types’ protection systems on Indoor Type Substation.
1.3 Specific Objective
The specific objective of this report includes:
? To study of a substation
? To study the major components of an indoor type substation
? To study the major components of indoor type substation
? To study the protection system of an indoor type substation
? To study the bus-bar arrangement system
? To make an analysis of total power consumption, various losses and power factor improvement.
? To specify the fault and their Troubleshooting
? To study consideration of a substation designing
1.4 Scope
The guidance and data in this report paper are intended to be used by operating and maintenance, personnel. It includes operating instructions, standard inspections, safety precautions and maintenance instructions.
1.5 Methodology
The research of this paper has been done with the help of the different sources. During the preparation of the paper several times it was cheeked by the authorized person of the SS Steel (Pvt) Ltd. The data was chosen accurately throughout the entire period of the session. Although there were several sources but here some are mentioned as for the proper references. The information of this report has been collected from the following sources:
? Management Manual
? Operation Manual
? Maintenance Manual
? Product Brochure and Catalog
? Quality Management Manual
? Environment, Health & Safety Manual
1.6 Limitations
This report has been prepared on the period of my practicum. Total paper was covered nicely through the time duration what was allocated for me. I show the practical implementation of everything. Although it was not expected but several times there were problems with most major equipments. Right here I had the opportunity came to check the entire maintenance, operation of the system. Along with the procedure my supervisor used to check up the documents by the in charge experts of the company.
1.7 Summary
For economic development of a country electricity is the main important part. We can’t thing without electricity in our daily life. However, electric power generating in power plant and transferred to the consumers into a substation. Substations are integral parts of a power system and form important links between the generating stations, transmission systems, distribution systems and the load points. Various power substations located in generating stations, transmission and distribution systems have similar layout and similar electrical components.
COMPANY PROFILE
2.1 About SS Steel
SS Steel (Pvt) Ltd., located in the heart of mill-gate road in Tongi, also known to be the oldest industrial region in Dhaka, Bangladesh; re-established the steel manufacturing business by its second generation family.
Nearly 26 years ago Kazi Shafi father of the 2 sons started the business that was dedicated solely to producing reinforcement-bars from small rolling mills. At the time rolling mills were fed with sheered and cut plates derived out of abandoned ships. Rods were produced to meet the needs for affordable steel and iron for the growing territories and basic infrastructure in the newly formed Bangladesh then.
Since the inception of the company SS Steel continued to expand its capability in every aspects of the production spectrum. Today we narrowed our product line to focus and become a Specialty Production Mill seeking to service a much more select group of demanding, quality-conscious customers.
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Fig. 2.1 Electric Induction Furnace
2.2 The Vision:
The Rod/Bar mill at SS Steel is unique in nature capable of producing rod products of fine quality compared to any mills of its kind and style. Product quality is ensured throughout the manufacturing processes in both Steelmaking and the Rod/Bar mill through strict adherence to process control requirements. Every SS Steel Mill employee is devoted to quality processes, quality products, and quality service. Each individual is focused on his or her responsibility within the process from hauling scrap to in-the-field customer service and understands how the power of synergy and the value of each facet of the process results in an exceptional outcome. Because SS Steel rod and bars and finished products meet the customer’s need, individual focus within a team environment creates an exceptional end product.
The knowledgeable and experienced personnel of SS Steel are committed to customer service through the development, manufacturing, delivery and installation processes. We know our success is dependent upon your satisfaction.
2.3 Finished Good:
Specializing in 500 TMT and 60 grade Re-bars/ Rods, we also produce 40 grade Re-Bars/ Rods from time to time to meet our clients requirement.
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Fig. 2.2 Rolling mill
2.4 Reinforced bar:
Various types of Re-Bar/ MS Rod producing in SS steel plant. There are
Grades | Sizes |
300 W / 40 | 10,12,16,20,22,25,28,32 |
400 W / 60 | 10,12,16,20,22,25,28,32 |
500 TMT | 10,12,16,20,22,25,28,32 |
2.5 Factory Setup:
SS of testing equipment are available in-house are available for our steel and steel is a composite A to Z solution for construction contractors and builders. The entire process from melting Mild Steel Scrap in induction furnaces to producing the end product, reinforced bars (Re-Bar/ MS Rod) at the rolling mills, is conducted in our own facility. An assortment rolling mill to produce deformed bar and plain bar using TMT technology to our client’s requirement.
2.6 Summary
SS Steel (Pvt) Ltd. one of the largest steel manufacturing companies in Bangladesh. They are producing reinforced bars (Re-Bar/ MS Rod) at the rolling mills by their own facilities. Product quality is ensured throughout the manufacturing processes in both Steelmaking and the Rod/Bar mill through strict adherence to process control requirements.
SUBSTATION
3.1 Introduction
The present-day electrical power system is ac i.e. electric power is generated, transmitted and distributed in the form of alternating current. The electric power is produced at the power stations which are located at favorable places, generally quite away from the consumers. It is delivered to the consumers through a large network of transmission and distribution. At many places in the line of the power system, it may be desirable and necessary to change some characteristic (e.g. voltage, current, ac to dc, frequency, p.f. etc) of electric supply. This is accomplished by suitable apparatus called sub-station. For example, generation voltage (11KV or 6.325KV) at the power station is stepped up to high voltage (say 230KV or 132KV) for transmission of electric power. The assembly of apparatus (e.g. transformer etc.) used for this purpose is the sub-station. Similarly, near the consumers’ localities, the voltage may have to be stepped down to utilization level. This job is again accomplished by a suitable apparatus called sub-station. Yet at some places in the line of the power system, it may be desired to convert large quantities of ac. Power to dc power e.g. for traction, electroplating, dc motors etc. This job is again performed by suitable apparatus (e.g. ignition) called sub-station.
3.2 Substation
The assembly of apparatus used to change some characteristic (e.g. Voltage, Current, a.c to d.c, frequency Hz, p.f etc) of electric supply is called a substation.
Fig. 3.1 Sub-station
An electrical substation is a subsidiary station of an electricity generation, transmission and distribution system where voltage is transformed from high to low or the reverse using transformers. Electric power may flow through several substations between generating plant and consumer, and may be changed in voltage in several steps. A substation that has a step-up transformer increases the voltage while decreasing the current, while a step-down transformer decreases the voltage while increasing the current for domestic and commercial distribution.
3.3 Importance of Substation
Substation is an important part of power system. The continuity of supply depends to a considerable extent upon the successful operation of sub-stations. It is therefore essential to exercise utmost care while designing and building substations. The following part is important point which must be kept in view while laying out a substation.
(i) It should be located at a proper site as far as possible it should be at the center of load.
(ii) It should provide safe and reliable arrangement. For safety consideration must be given to the maintenance abnormal occurrence such as possibility of explosion or fire etc. Consideration must be given for design and constriction. The provision of suitable protection gear etc.
(iii) It should be easily operated and maintenance.
(iv) It should involve minimum capital cost.
3.4 Functions of a Substation
Substations are designed to accomplish the following functions, although not all substations have all these functions:
{C}· Change voltage from one level to another.
{C}· Regulate voltage to compensate for system voltage changes.
{C}· Switch transmission and distribution circuits into and out of the grid system.
{C}· Measure electric power qualities flowing in the circuits.
{C}· Connect communication signals to the circuits.
{C}· Eliminate lightning and other electrical surges from the system.
{C}· Connect electric generation plants to the system.
{C}· Make interconnections between the electric systems of more than one utility.
- Control reactive kilovolt-amperes supplied to and the flow of reactive kilovolt- amperes in the circuits.
- Supply electric power to the consumers continuously.
- Supply of electric power within specified voltage limits and frequency limits shortest possible fault duration.
- Optimum efficiency of plants and the network
- Supply of electrical energy to the consumers at lowest cost
3.5 Classification of substation
According to Service Requirement
1. Transformer Substation.
2. Switching substation.
3. Power factor correction substations.
4. Frequency changer substations.
5. Converting substation.
6. Industrial substation.
According to Constructional Feature the Substation are Classified as
1. Indoor substation.
2. out door substation.
According to Based on Operation Voltage
1. Ultra High Voltage Electrical Power Substation.
2. Extra High Voltage Electrical Power Substation.
3. High Voltage Electrical Power Substation.
According to Based on Design Configuration
1. Air Insulated Electrical Power Substation.
2. Gas Insulated Electrical Power Substation.
3. Hybrid Electrical Power Substation.
3.5.1 Transformer substation
Those substations which change the voltage level of electric supply are called transformer substation. These substations receive power at some voltage and deliver it at some other voltage. Obviously, transformer will be the main component in such substation. Most of the substations in the power system are of this type.
3.5.2 Switching Substation
These substations do not change the voltage level i.e. incoming and outgoing lines have the same the voltage. However, they simple perform the switching operations of power lines.
3.5.3 Power Factor Correction Substation
Those substations which improve the power factor of the system are called power factor correction substations. Such substation is generally located at the receiving end of transmission lines. These substations generally are use synchronous condensers as the power factor improvement equipment.
3.5.4 Frequency Changer Substation
Those substations which change the supply frequency are known as frequency changer substation. Such a frequency change may be required for industrial utilization.
3.5.5 Converting Substation
Those substations which change a.c power into d.c power are called converting substations. These substations receive a.c power converting into d.c power with suitable apparatus (e.g. Ignitron) to supply for such purpose as traction electroplating electric welding etc.
3.5.6 Industrial Substation
These types of substations which supply power to individual industrial concerns are known as industrial substations.
3.5.7 Indoor Substation
In indoor power substations the apparatus is installed within the substation building. Such substations are usually for the rating of 66kv. Indoor substations are preferred in heavily polluted areas and power substations situated near the seas (saline atmosphere causes insulator failures results in flashovers).
Fig. 3.2 Indoor Substation
3.5.8 Outdoor Substation
In outdoor power substations, the various electrical equipments are installed in the switch yard below the sky. For voltage beyond 66kv equipment is invariably installed out door. It is because for such voltage the clearance between conductor and the space required for switch, circuit breaker and equipment becomes so great it is not economical to install the equipment indoor.
3.5.9 High Voltage Electrical Power Substation
This type of substation associated with operating voltages between 11kv and 66kv.
3.5.10 Extra High Voltage Electrical Power Substation
This type of substation is associated where the operating voltage is between 132kv and 400kv.
3.5.11 Ultra High Voltage Electrical Power Substation
Substations where operating voltages are above 400kv are called ultra high voltage substation.
3.5.12 Air Insulated Electrical Power Substation
In air insulated power substations bus bars and connectors are visible. In this power substations circuit breakers and isolators, transformers, current transformers, potential transformers etc are installed in the outdoor. Bus bars are supported on the post insulators or strain.
Insulators substations have galvanized steel structures for supporting the equipment, insulators and incoming and outgoing lines. Clearances are the primary criteria for these substations and occupy a large area for installation.
3.5.13 Gas Insulated Electrical Power Substation
Fig. 3.3 Gas Insulated Substation
In gas insulated substation has various power substation equipments like circuit breakers, current transformers, voltage transformers, bus bars, earth switches, surge arresters isolators etc are in the form of metal enclosed SF6 gas modules. The modules are assembled in accordance with the required configuration. The various live parts are enclosed in the metal enclosures (modules) containing SF6 gas at high pressure. Thus the size of power substation reduces to 8% to 10% of the air insulated power substation.
3.5.14 Hybrid Electrical Power Substation
Hybrid substations are the combination of both conventional substation and gas insulated substation. Some bays in a power substation are gas insulated type and some are air insulated type. The design is based on convenience, local conditions available, area available and cost.
3.6 Substation Types