Luchkin Dmitriy

Faculty: Electrotechnical
Speciality: Electric systems of electroconsumption

Theme of master's work:

Power supply features planning of dwellings buildings with the TN-C-S system

Scientific adviser: Bershadskiy Ilya

Summary of research and developments

Introduction

    Presently the number of new buildings is increased every day. However after appearance seventh edition of "Rules device of Electrical Installation(REI)", the necessary method of calculations, collected together, is not yet present. Information has to be collected on grains from mass of different sources. Therefore development of single manual would be very useful to many designers

    Practical value:

    The example of calculation of loadings is resulted in this work, sections of explorers, choice of facilities of defence for seventeenfloors of dwelling-house with built-in office apartments with the system of feed of TN-С-S. On the basis of this work the analogical calculations of электроснабжения of multistory dwelling-houses can be conducted.

    System of feed of TN-C-S:

    In accordance with REI in the apartments of dwellings buildings must join in with protective explorers metallic corps of electro-receivers, and wall outlet networks are executed, accordingly, by a three-wire. That, application of the system of feed of TN-C-S is regulated in dwellings buildings (fig. 1)

     In the system of TN-С-S the electric power from substation to the user is given by a fourwire cable are three phase explorers and one neutral (REN) explorer, uniting functions working and protective neutral explorers.

    In the system of TN-С-S a neutral (REN) explorer is divided on working (N) and protective (PE) explorers in a distributive corymb.

    The system of TN-С-S, as well as system of TN-S, provides the effective protecting from lines and indirect touches and allows to apply three-wire wall outlets.

     Calculation loading of group of habitation with the identical specific electric loading, resulted to the line of feed, input in a dwelling-house, tires by tension 0,4 кV:

     where - is the specific calculation electric loading of one habitation (apartments), which gets out from a table 1 depending on the accepted level of electrification and amount of apartments, added to this link of the electric system

    N - is an amount of apartments, added to the input, line

    The specific calculation electric loadings of habitation engulf loading of illumination of apartments.

    Calculation loading of power electro-receivers of dwelling-house:

    where Рл1 …Рлп - power of electric motor each of elevators on a passport

    Кпоп.л- coefficient of demand for elevators;

    Рсан1 …Рсанп - power of every electric motor of sanitary engineerings options is set on their passports

    Кпоп.сан -coefficient of the electric motors of sanitary engineerings options

    The calculation loading of dwelling-house

Ргр1…Ргрп - loadings of built-in or built on public apartments

     Loadings in office apartments

    where- power of working illumination

-coefficient of demand of working illumination depending on its set power

     Calculation electric loading of lines which feed wall outlets:

    where Рроз.ус- is set power of wall outlet;

    Nроз - amount of wall outlets.

    Кпоп.рез - coefficient of demand

    office apartments 50 wall outlets are set by power of 0,5кW and 33 wall outlets by power of 0,2кW.

    We choose a cable ВВГнгLS-4х70 + 1х35 with Iдоп=185А.

    Conclusions:

     Some elements for apartments and cottages are obligatory. Namely:

    1. An absolute requirement of legislation is a presence of automats of defence in a distributive corymb. They must be set on every incoming and going out line, and to protect электроустановку from short circuits and protracted overloads. Their main task - in case of occurring of emergency case to disconnect a line so quickly, that wiring did not have time to burn up. Time of disconnecting must be a no more than 0,4 sec. Thus, the choice of automats must be grounded calculations.

    2. Except for the automats of maximal current, application of automats of differential current is obligatory - UZO, which serve for protecting of both people from a touch to токоведущим parts of equipment or wiring and электроустановки from the different sort of losses on earth. Last, very unpleasant, arise up in the most unexpected places and can cause the self-ignition of equipment, wirings. Task of UZO - to disconnect a line in case of occurring of loss. An amount and face values of these automats settle accounts a designer.

    3. The electric wiring of apartment or cottage is executed only the copper send-offs of certain types. Aluminium wires are used only for external cable or air busses. In cottages from combustible materials of wire must be opened, I.e. to be outside of walls in the special cable channels. The electric wiring of apartment is executed usually hidden into walls. In the case of error, its replacement very expencive.

    Literature

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