Welding Equipment Plant Power Supply -Diform Project

Contents

1 Introduction

1.1 Main provisions of power supply system

1.2 Initial data

1.3 Brief description of the plant and its electric receivers

2 Main part

2.1 Calculation of electrical loads

2.1.1 Calculation of electrical loads of the mechanical assembly shop

2.1.2 Calculation of lighting load of mechanical assembly shop

2.1.3 Calculation of plant lighting load

2.1.4 Calculation of electrical loads of the plant

2.2 Cartogram of electrical loads

2.3 Selection of rational power supply voltages

2.4 Selection of number and capacity of transformers of shop substations and their location

2.5 Calculation and selection of compensating devices power

2.6 Selection of plant power supply scheme

2.7 Calculation and power selection of transformers of the main lowering substation

2.8 Calculation of short-circuit currents on the high voltage side

2.9 Selection and check of high-voltage equipment

2.9.1 High Voltage GPP Equipment Selection

2.9.2 Selection of packaged switchgears and high voltage switches

2.9.3 Selection of 10 kV current transformers

2.9.4 Selection of voltage transformers on the 10 kV side

2.9.5 Selection of disconnectors and fuses for shop TPs

2.9.6 Selection of auxiliary transformers

2.9.7 Calculation and selection of cable section

2.10 Selection of relay protection of GPP transformers

2.11 Calculation of relay protection of the cable line supplying the transformer

2.12 Calculation and selection of components of the workshop power network

2.13 Calculation of short-circuit currents up to 1000 V

2.14 Calculation and selection of components of the lighting network of the workshop

2.15 Energy accounting and measurement of electrical parameters in the electrical plant

3 Occupational and environmental protection

3.1 Calculation of lightning protection of the main lowering substation

3.2 Calculation of grounding device of shop transformer substation

3.3 Safety measures during works on cable lines

3.4 Water pollution

4 Economic part

4.1 Organization of repairs and determination of the number of repair and maintenance personnel

4.2 Payroll Cost Calculation

4.3 Define Material and Spare Parts Requirements

4.4 Calculation of annual depreciation charges

4.5 Determination of annual cost of purchased energy

4.6 Calculation of Power Cost

Conclusion

List of literature

Introduction

1.1 Main provisions of power supply system

Electric energy is widely used in all areas of the national economy and in everyday life. This is facilitated by its properties such as versatility and ease of use, the possibility of production in large quantities by an industrial method and transmission over long distances.

Simultaneously with the beginning of the use of electric energy for the operation of electric drives of various technological plants, the task of distributing and transmitting electric energy arose. On the day of practical resolution of these issues, a power supply system is used, which is a set of devices necessary for the production, transfer and distribution of electric energy to electrified processes. As the latter evolve, so does the electricity supply itself. In this regard, questions about the reliability and quality of electricity supply are very acute. Currently, these two factors are maintained during operation, are provided during installation and are embedded in the design of power supply systems. Therefore, when providing an industrial facility with electricity, the necessary level of reliability and quality of electric energy corresponding to a particular category of consumer should be set initially, at the design stage. After all, the structure and characteristics of consumers determine the conditions for the construction of their power supply scheme. Therefore, when designing the power supply system, a thorough analysis of the nature and composition of the connected load must be carried out. Further, based on this analysis, a specific power supply system is created that provides a given level of reliability and quality of power supply.

The purpose of this diploma project is to develop a rational power supply system for the welding equipment plant.

To achieve this goal, the following tasks must be achieved:

- calculate electrical loads of characteristic groups of electric receivers and units, as well as the whole enterprise;

- determine the structure of the SES: the location of the GPP, shop substations, distribution points, the number and capacity of transformers, reactive power compensation;

- determine the rational supply voltage and distribution of electricity, as well as the methods of sewerage of electricity in the territory of the plant;

- to choose types and types of equipment and equipment taking into account their operating conditions, requirements of reliability, safety, flexibility and economy.

1.3 Brief description of the plant and its electric receivers

The welding equipment plant includes 11 workshops, 8 of which are production: the main building, mechanical assembly, tool, mechanical, blacksmith, stamping, assembly, foundry and laboratory testing building. The plant also includes plant management, compressor and pumping stations. The compressor has 4 synchronous motors with a power of 800 kW each for a voltage of 10 kV.

The main consumers in most workshops are electrical receivers of category IIII of reliability of power supply, the disconnection of which can lead to a violation of the technological cycle and mass underdelivery of products. In a number of workshops there are also consumers of category I of reliability of power supply - equipment of pumping and compressor stations. The III categories of reliability of power supply include: finished product warehouse, material warehouse and plant management .

Production consumers include power plants, lighting plants, electric drives of production mechanisms, electrothermal and galvanic plants.

Power plants of general industry include: compressors, fans, pumps. Motors of compressors, fans and pumps operate in a continuous mode and, depending on the power, are supplied with electric energy at a voltage of 0.22 to 10 kV. The capacity of such installations varies in a very wide range from fractions of a unit to thousands of kilowatts. Motors are powered by 50 Hz industrial frequency current. The nature of the load is usually even, especially for powerful installations. Interruption in power supply is most often unacceptable and can lead to a danger to people's lives, a serious violation of the technological process or damage to equipment.

For the electric drive of large pumps, compressors and fans, synchronous motors are most often used, operating with an advanced power factor.

Lifting and transportation devices operate in a re-short-term mode. These devices are characterized by frequent loads. Due to sudden changes in load, the power factor also varies significantly, from an average of 0.3 to 0.8.

Electric motors of production mechanisms are found in all production enterprises. For the electric drive of modern machines, all types of engines are used. Engine power is extremely diverse and varies from fractions to hundreds of kilowatts and more. In machines where high speeds of rotation and its regulation are required, DC motors powered by rectifier units are used. Mains voltage 380/220 V with frequency 50 Hz. The power factor varies widely depending on the process. In terms of reliability of power supply, this group of receivers belongs, as a rule, to category II.

The lighting load is uniform, but its value varies significantly depending on the time of day, year and geographical location of the object. Electric lamps are a single-phase load, however, due to the insignificant receiver power (usually not more than 2 kW) in the electric network, with the correct grouping of lighting devices, a fairly uniform load can be achieved in phases (with an asymmetry of not more than 510%). The current frequency is industrial, equal to 50 Hz. The power factor for filament lamps is 1, for gas discharge lamps 0.6. It should be borne in mind that in wires, especially zero, when using gas discharge lamps, higher current harmonics appear.

Short-term (several seconds) emergency interruptions in the power supply of lighting installations are permissible. Long breaks (minutes and hours) in nutrition for some types of production are unacceptable. In such cases, power redundancy from the second, current source (in some cases even from an independent DC source) is used. For lighting installations of industrial enterprises, voltages from 6 to 220 V.

Electric thermal receivers of industrial enterprises in accordance with heating methods are divided into the following groups: arc electric furnaces for melting of ferrous and non-ferrous metals, induction heating plants for melting and heat treatment of metals and alloys, electric resistance furnaces and electric welding plants. The welding equipment plant has resistance furnaces, induction and welding plants.

Resistance furnaces according to the heating method are divided into indirect furnaces and direct furnaces. Heating of material in indirect furnaces occurs due to heat generated by heating elements when electric current passes through them. Indirect heating furnaces are installed with voltage up to 1000 V and are supplied in most cases from 380 V networks of industrial frequency 50 Hz. Furnaces are produced with one- and three-phase power from units to several thousand kilowatts. The power factor is in most cases 1.

In direct furnaces, heating is carried out by heat released in the article being heated when electric current passes through it. Furnaces are made with single and three-phase power up to 3000 kW; power supply is carried out by 50 Hz industrial frequency current from 380/220 V. Most resistance furnaces with respect to uninterrupted power supply belong to electric power receivers of the second category.

AC electric welding plants operate at an industrial AC frequency of 50 Hz and represent a single-phase load in the form of welding transformers for arc welding and contact welding devices. AC welding produces a single-phase load with a re-short-term mode of operation, an uneven phase load and, as a rule, a low power factor (0.30.35 for arc and 0.40.7 for contact welding). Welding plants are powered by 380220 V. From the point of view of reliability of power supply, welding plants belong to electric power receivers of the 2nd category.

Part of the project is the development of a power supply system for the mechanical assembly workshop. Milling, drilling, grinding, turning, boring machines are installed in the workshop.

Mechanical assembly workshop is designed for mass production of parts and assembly of units. The workshop has production and auxiliary rooms.

Consumers of electrical power of the workshop belong to category II and III in terms of reliability and uninterrupted power supply.

On lathes, external, internal and end surfaces of bodies of rotation of cylindrical, conical and shaped shape are treated, as well as grooves are cut, external and internal threads are cut.

Grinding machines serve for finishing of external and internal surfaces of parts.

Drilling machines are used to obtain through and blind holes in parts by means of drills, boring of holes by cutters and clean treatment of holes previously obtained by casting or stamping, and other operations.

When placing equipment, distance standards for safe movements of parts and workers themselves during operation are taken into account.

For transportation of parts and assemblies, as well as for loading and unloading of blanks received from other workshops of the plant, bridge cranes are installed in the workshop.

The mechanical assembly workshop in terms of environmental characteristics refers to rooms with normal conditions. The relative humidity in the room in the warm period of the year is 4044%, and in the cold - 40%, the air temperature is 1822 ° C.

In relation to the danger of electric shock, according to the PUE, the mechanical assembly workshop refers to a room with increased danger as it has: conductive floors (metal and reinforced concrete) and the possibility of simultaneously touching a person to metal structures of buildings and technological devices connected to the ground on one side and to metal buildings of electrical equipment on the other.

Work in workshops is provided in three and two shifts, plant management - in one.

2 main part

2.1 Calculation of electrical loads

The beginning of the design of the plant's power supply systems is the determination of electrical loads.

The design power consumed by the electric receivers of the enterprise is always less than the sum of the nominal capacity of these EP. The need to determine the design loads of the welding equipment plant is caused by the incomplete loading of some EPs, the non-simultaneous operation of them, the probabilistic random nature of switching on and off the EP, depending on the peculiarities of the technological process and organizational and technical measures to ensure the proper working conditions of workers and employees of this production. The correct determination of the expected electrical loads and ensuring the necessary degree of uninterrupted power supply are of great importance for the entire subsequent calculation and selection of elements of the power supply system of the enterprise.

Load calculation is performed in accordance with "Instructions for calculation of electrical loads" RTM 36.18.32.492, introduced from January 1, 1993. First, the load of the mechanical assembly workshop is calculated, then for the plant as a whole.

When calculating loads, it is taken into account that the load of objects (workshop, enterprise) consists of power and lighting. The calculated power load is calculated using the utilization factors and the calculated load. Loading of electric lighting is determined by the specific power of Ores. about depending on the required illumination.

3.3.3 Cutting of cable, opening of couplings

Before cutting the cable or opening the couplings, make sure that the work will be done on the cable to be repaired, that this cable is disconnected and that technical measures have been taken.

At the workplace, the cable to be repaired must be determined:

when laying in a tunnel, collector, channel - tracing, checking the layout with drawings and diagrams, checking by tags;

when laying cables in the ground - by checking their location with the gasket drawings.

For this purpose, a test trench (pit) must be previously dug across the cables, allowing you to see all the cables.

Before cutting the cable or opening the coupling, it is necessary to check the absence of stress using an insulating rod and a steel needle or cutting tip. The accessory shall provide puncture or cutting of the shell to the cores with their closure to each other and grounding.

The cable at the piercing point must be previously covered by a screen.

When puncturing the cable, use workwear, dielectric gloves and face and eye protection, and it is necessary to stand on an insulating base on top of the trench at the maximum distance from the pierced cable.

The cable puncture shall be performed by two employees: the admissible and the work manufacturer or the manufacturer and the responsible work manager; one of them, having undergone special training, directly punctures the cable, and the second - observes.

For grounding of the piercing device, a grounding conductor immersed in soil to a depth of at least 0.5 m or cable armor can be used. Connect the grounding conductor to the armor by means of clamps; armor under the clamp must be cleaned.

Where the armor has been corroded, the grounding conductor may be connected to the metal sheath of the cable.

On the cable lines of power plants and substations, where the length and method of laying cables allow, using drawings, tags, cable and a searcher, to accurately determine the cable to be repaired, it is allowed, at the discretion of the dispenser, not to pierce the cable before cutting or opening the coupling.

Open the couplings and cut the cable in cases where no preliminary puncture is made, follow the grounded tool by wearing dielectric gloves, using face and eye protection, standing on an insulating base.

3.3.4 Heating of cable mass and filling of couplings

Cable mass for filling couplings shall be heated in special iron utensils with cover and spout.

Cable mass is removed from the opened can using a heated knife in the warm season, and is pulled off - in the cold season.

Do not warm up unopened cans with cable mass.

When filling couplings with mass, the employee must be wearing special clothes, tarpaulin sleeves and safety glasses.

Heating, removal and transfer of soldered receptacle as well as bulk receptacle shall be performed in canvas hoses and safety goggles. It is not allowed to transfer a solder vessel or a vessel with a mass from hand to hand, when transferring, it is necessary to put them on the ground.

Mixing of the molten mass should be carried out with a metal stirrer, and removal of coke from the surface of the molten solder - with a metal dry spoon. The stirrer and spoon must be heated before use.

In the cold season the connecting and end couplings must be heated before being filled with their hot compositions.

Heating of cable mass in cable wells, tunnels, cable structures is not allowed.

3.4 Water pollution

Pollution of water bodies refers to a decrease in their biosphere functions and economic significance as a result of the introduction of harmful substances into them .

One type of water pollution is thermal pollution. Power plants, industrial enterprises often discharge heated water into the reservoir. This leads to an increase in the temperature of the water in it. As the temperature in the reservoir increases, the amount of oxygen decreases, the toxicity of water contaminants increases, and biological equilibrium is disturbed.

In contaminated water, with an increase in temperature, pathogens and viruses begin to rapidly multiply. Once in drinking water, they can cause outbreaks of various diseases.

In a number of regions, groundwater was an important source of fresh water. Previously, they were considered the cleanest. But at present, as a result of human economic activity, many sources of groundwater are also contaminated. Often, this pollution is so large that the water from them has become unsuitable for drinking.

Mankind consumes a huge amount of fresh water for its needs. Its main consumers are industry and agriculture. The most water-intensive industries are mining, steel, chemical, petrochemical, pulp and paper and food. They take up to 70% of all water spent in industry. The main consumer of fresh water is agriculture: 6080% of all fresh water is spent on its needs.

In modern conditions, human water needs for communal needs are greatly increasing. The amount of water consumed for these purposes depends on the region and the standard of living, ranged from 3 to 700 liters per person. In Moscow, for example, each resident accounts for about 650 liters, which is one of the highest rates in the world.

From the analysis of water use over the past 5-6 decades, it follows that the annual increase in irretrievable water consumption, in which used water is irretrievably lost to nature, is 45%. Promising calculations show that if such consumption rates are maintained and taking into account population growth and production volumes by 2100, humanity can exhaust all fresh water supplies.

Already, the lack of fresh water is experienced not only by the territories that nature has endowed with water resources, but also by many regions that have recently been considered prosperous in this regard. Currently, 20 per cent of the world's urban and 75 per cent of the rural population does not have fresh water.

Limited freshwater supplies are further reduced by pollution. The main danger is wastewater (industrial, agricultural and household), since a significant part of the used water is returned to water basins in the form of wastewater.

The water quality of most water bodies does not meet regulatory requirements. Long-term observations of surface water quality trends show a tendency to increase the number of high-level (more than 10 MPC) and extreme-high (more than 100 MPC) contaminants in water bodies.

The state of water sources and centralized water supply systems cannot guarantee the required quality of drinking water, and in a number of regions (South Ural, Kuzbass, some territories of the North) this state has reached a dangerous level for human health. Sanitary and epidemiological surveillance services constantly note high pollution of surface waters.

About 1/3 of the total mass of pollutants is introduced into the water by sources with surface and storm runoff from the territories of sanitary areas, agricultural facilities and land, which affects the seasonal, during the spring flood, deterioration in the quality of drinking water, annually observed in large cities, including Moscow. In this regard, water is hyperchlorinated, which, however, is unsafe for public health due to the formation of organochlorine compounds.

One of the main pollutants of surface water is oil and petroleum products. Oil can enter the water as a result of its natural exits in the areas of occurrence. But the main sources of pollution are related to human activities: oil production, transportation, processing and use of oil as fuel and industrial raw materials.

Among industrial products, toxic synthetic substances occupy a special place in their negative effects on the aquatic environment and living organisms. They are increasingly used in industry, transport, and public utilities. The concentration of these compounds in the wastewater is typically 515 mg/l at a MPC of 0.1 mg/l. These substances can form a layer of foam in reservoirs, especially noticeable on rapids, rifts, locks. The foaming ability of these substances appears already at a concentration of 1-2 mg/l.

The most common contaminants in surface waters are phenols, easily oxidizable organic substances, copper, zinc compounds, and in some regions of the country - ammonium and nitrate nitrogen, lignin, xanthogenates, aniline, methyl mercaptan, formaldehyde, etc. A huge amount of pollutants is introduced into surface waters with wastewater of ferrous and non-ferrous metallurgy enterprises, chemical, petrochemical, oil, gas, coal, forestry, pulp and paper industries, agricultural and municipal enterprises, surface runoff from adjacent territories.

Mercury, lead and their compounds pose a small risk to the aqueous environment from metals.

Expanded production (without treatment facilities) and the use of toxic chemicals in the fields lead to heavy pollution of water bodies with harmful compounds. Pollution of the water environment results from direct introduction of toxic chemicals when processing reservoirs for pest control, receipt in reservoirs of the water which is flowing down from a surface of the processed agricultural grounds when dumping into reservoirs of waste of predpriyatiyproizvoditel and also as a result of losses during the transporting, storage and partially with an atmospheric precipitation.

Along with toxic chemicals, agricultural effluents contain a significant amount of fertilizer residues (nitrogen, phosphorus, potassium) introduced into the fields. In addition, large quantities of organic nitrogen and phosphorus compounds come from livestock farms, as well as sewage. An increase in the concentration of nutrients in the soil leads to a violation of biological balance in the reservoir.

Initially, the number of microscopic algae increases dramatically in such a reservoir. With an increase in the feed base, the number of crustaceans, fish and other aquatic organisms increases. Then a huge number of organisms die off. It leads to the consumption of all oxygen supplies contained in the water and the accumulation of hydrogen sulfide. The situation in the reservoir is changing so much that it becomes unsuitable for the existence of any form of organisms. The reservoir is gradually "dying."

The current level of wastewater treatment is such that even in biodegradable waters, the nitrate and phosphate content is sufficient for intensive eutrophication of reservoirs.

Eutrophication - enrichment of the reservoir with biogens, stimulating the growth of phytoplankton. From this, the water becomes cloudy, benthic plants die, the concentration of dissolved oxygen decreases, fish and mollusks living at the depths suffocate.

In many water bodies, pollutant concentrations exceed the MPC established by sanitary and conservation regulations.

Not only surface water but also groundwater is contaminated. In general, the state of groundwater is assessed as critical and has a dangerous trend of further deterioration.

Underground waters (especially upper, shallow, aquifers), following other elements of the environment, are polluting human activities. Groundwater is affected by pollution from oil fields, mining enterprises, filtration fields, sludge accumulators and dumps of metallurgical plants, chemical waste and fertilizer storage facilities, landfills, livestock complexes, and non-sewage settlements. There is a deterioration of water quality as a result of tightening of substandard natural waters in case of violation of the water intake operation mode. The areas of groundwater pollution reach hundreds of square kilometers.

Of the substances polluting underground water, predominant: petroleum products, phenols, heavy metals (copper, zinc, lead, cadmium, nickel, mercury), sulfates, chlorides, nitrogen compounds .