Power supply of lighting installations. Power supply system. lighting calculation methods
The book sets out theoretical basis and practical data on the device, design and operation of lighting installations are given. The choice of normalized characteristics, the type of light sources, types and systems of lighting, power supply and control circuits, as well as the issues of calculating lighting and lighting networks are considered.
Everyone has to deal with artificial lighting installations on a daily basis, and of all engineering devices, they are perhaps the most massive. Their implementation and operation require large expenditures of material resources, electricity and human labor, but these costs are paid off in excess by ensuring the possibility of a normal life and activity of people in the absence or insufficiency of natural light. Moreover, artificial lighting solves a number of problems that are generally inaccessible to natural lighting, while labor productivity, work safety, vision safety, and the architectural appearance of the room largely depend on the features of the artificial lighting device, which sometimes seem very insignificant.
The proposed book deals with the design, installation and operation of lighting installations and is mainly intended to serve as a practical guide for employees of organizations, enterprises and sanitary inspectors. Approximately similar in content to curriculum course "Lighting installations", read for students of technical schools of specialization 0632 "Lighting devices and installations", Department of Lighting Engineering MPEI, it can also serve study guide at the indicated rate.
The purpose and volume of the book make it necessary to emphasize that it is in no way a course in lighting engineering in general and is intended for people who are familiar with the basics of lighting engineering, as well as those who have general information about light sources and lighting fixtures. Only as a brief reminder at the beginning of the book is a list of basic concepts and relationships.
The book should not be considered as a reference tool either: the volume of reference materials needed only for lighting design exceeds the entire volume of this book.
Foreword
Chapter one. Fundamental principles of lighting installations
1-1. Basic lighting units in ratio
1-2. Vision and lighting
1-3. Lighting rationing principles
1-4. Color in lighting technology
1-5. Lighting quality.
Chapter two. Lighting part of lighting installations
Lighting choice.
2-2. Lighting systems.
2-3. Types of lighting
2-4. Choice
2-5. Location of fixtures
2-6 Characteristics and classification of luminaires
2-7 Selection of luminaires according to lighting characteristics
2-8 Economic feasibility of choosing the type of luminaire
2-9 Choice of luminaire design
2-10. general characteristics range of luminaires.
2-11. Slit light guides.
Chapter three. Illumination calculation.
3-1. Basic principles of calculation.
3-2 Utilization method
3-3. Simplified forms of the utilization factor method.
3-4. Point method
3-5. Special Calculation Methods
3-6. Projector lighting.
Chapter Four. Calculation of the qualitative characteristics of lighting
4-1. Cylindrical illumination
4-2. Ripple factor
4-3. Average brightness of road surfaces
Chapter five. Power supply of lighting installations.
5-1. Lighting voltage.
5-2. Power supplies and supply networks.
5-3. group networks.
5-4. Lighting control schemes.
Chapter six. Electrical networks of lighting installations
6-1. Implementation of lighting networks.
6-2. Selection of the cross-section of conductors according to the load current and protection of lighting networks
6-3. Calculation of networks by voltage loss
6-4. Grounding, grounding and travel wires
Chapter seven. Lighting features of some objects
7-1. General information
7-2. Fire and explosion hazardous areas
7-3. Premises of public buildings.
7-4. Architectural and artistic lighting
7-5. Illumination of open spaces.
Chapter eight. Design, operation and economic feasibility of the choice of lighting installations.
8-1 Organization and methodology of design work
8-2. Working design stage.
The supply lines in lighting networks include networks from the power source (transformer substation or input to the building) to group electrical panels. Lines running from group switchboards to lamps are called group lines.
The power lines of lighting installations, as well as power lines, can be made according to mixed schemes.
The radial scheme is used extremely rarely. This is due to its high cost and high consumption of non-ferrous metals. The basis for choosing a power supply circuit for lighting electrical installations are the requirements for, convenience and ease of management and operation, as well as efficiency.
Lighting schemes for industrial buildings
The most important of the above requirements is the reliability of power supply. After all, a suddenly extinguished light can lead not only to a stop production processes but also to accidents with people. That is why, for many civil and industrial buildings, the PUE requires the creation of emergency lighting, which will remain on after the main one goes out. It is necessary that emergency lighting fixtures be connected to an independent power source.
Fulfillment of these requirements is achieved by applying the appropriate constructions of lighting network diagrams. The most common schemes are indicated:
Figure a) shows the main power supply circuit of group shields. The emergency lighting panel is connected to a separate main, which goes directly from the switchboard of the workshop transformer substation. If there are two transformer substations, the lighting sources will be powered by two different transformers (Figure b)).
Using the "" scheme, the working lighting network will be connected directly to the busbar. In the case of a significant load current, a main shield is installed under the current duct, from which distribution to group shields will occur. Emergency lighting boards are connected to the secondary busbar:
For critical facilities in the presence of two or more substations, a cross emergency lighting system is used:
Lighting schemes for civil buildings and residential buildings
In civil and industrial buildings, the principles for building lighting networks are slightly different. In civil buildings, the supply lines lead to the center of a residential building in the basement or stairwell of the first floor, where an introductory switchgear is installed. From the input switchgear, horizontal supply lines will diverge in both directions, which are laid either along the floor of the first floor or along the basement. Lines located vertically along the floors (risers) are connected to the horizontal supply lines. They are connected to the risers, from which the apartments are powered. Depending on the load, the number of group shields and the volume of the building, several risers can be connected to each supply line.
In residential buildings above five floors, when fed from one line to several risers, each branch to the riser must be equipped with protective apparatus. Electricity consumption can be metered both in the apartments themselves and in special cabinets on stairwells. When installing protection devices and electric meters of group networks in common cabinets on stairwells built into electrical panels, and at a distance from stair risers to these cabinets not exceeding 3 meters, floor shields are not installed. Staircase lighting is powered by an introductory distribution point and is centrally controlled.
It is also worth noting that photo switches installed in the entrances of residential buildings are becoming quite popular. The photo switch automatically turns on the lighting at nightfall and turns it off in the daytime. In houses with a height of more than 9 floors, a time relay or special microprocessor devices with clockwork can be introduced into the circuit, which turn the lights on and off according to a certain algorithm. Thus, energy savings are realized.
A scheme is also used with the installation of so-called stair circuit breakers on each landing. These machines operate with a certain time delay and turn off the lighting after a certain period of time. With this scheme, a person walking up the stairs washes the light on or off at the next site, which saves quite a lot of electricity, but this is not very convenient for the elderly or when carrying heavy loads.
Power supply schemes for residential buildings with a height of six to sixteen floors have additional features, as they belong to category 2 consumers. In such houses there are elevators, and sometimes pumps to maintain the pressure of water in the water pipes.
The power supply diagram of a residential nine-story building is shown below:
It can be seen from the diagram that the power supply of this facility is provided by two mutually redundant lines designed to power the entire building (in emergency mode). In the event of a power failure on one of the lines, using a switch, the load of the house is transferred to another supply line. The risers pass through the electrical panels on the staircases, where protection devices and electric meters of apartment networks are installed, therefore, in this case, floor shields are not installed. Emergency lighting fixtures are separately attached to the power input. Electric meters common to the entire building are installed at the inputs.
Electric lighting is supplied, as a rule, together with power receivers from common three-phase power transformers with a solidly grounded neutral with a secondary voltage of 400/230 V. The rated voltage in such networks is 380/220 V.
Electric lighting networks are divided into supply, distribution and group.
Supply lighting network - a network from a switchgear of a substation or a branch from overhead power lines to an input device (VU), an input distribution device (ASU), a main switchboard (MSB).
Distribution network - a network from VU, ASU, MSB to distribution points, shields and lighting power points.
Group network - a network from shields to lamps, sockets and other electrical receivers.
Input device (VU) - a set of structures, devices and devices installed at the input of the supply line to the building or its separate part.
An input-distribution device (ASU) is an input device, which also includes devices and devices of outgoing lines.
An input-distribution device (ASU) is an input device, which also includes devices and devices of outgoing lines. Input-distribution device (ASU) - refers to the type of low voltage electrical devices and is used in networks with a rated voltage of up to 380 V AC with a frequency of 50 Hz. ASU (input distribution device) protects lines from network overloads and short circuits, receives and distributes electricity.
ASU is classified according to the following main features:
by design (single-panel ASU, multi-panel ASU, cabinet ASU);
at the place of installation (in switchboard rooms, outside these rooms (for example, outdoor version));
by type of installation (floor-mounted ASP, wall-mounted ASP, recessed ASP);
according to the degree of protection;
according to input schemes (one input, two inputs, two inputs with sectioning, etc.);
by the presence of ATS (automatic transfer unit);
by access of service personnel (qualified, unskilled).
The input-distribution device (ASU) is most often located in the power supply system of a building (structure) at an average level of power distribution with a voltage of 0.4 kV after the main switchboard. But they can also be located at the top level as the main switchboard building.
The main switchboard (MSB) is a switchboard through which the entire building or its separate part is supplied with electricity.
Group shield - a device in which protection devices and switching devices (or only protection devices) are installed for individual groups of lamps, plug sockets and stationary electrical receivers.
With regard to ensuring the reliability of power supply, power receivers are divided into the following 3 categories:
I - electrical receivers, the interruption in the power supply of which can lead to a danger to people's lives, a threat to the security of the state, significant material damage, a disorder of a complex technological process;
II - electrical receivers, a break in the power supply of which can lead to a massive underproduction, massive downtime of workers, mechanisms, vehicles, etc.
III - electrical receivers that do not fall under the definitions of the first and second categories.
Some typical power supply schemes for lighting installations industrial buildings shown in fig. 3.2 - 3.7.
On fig. 3.2 shows the power supply circuits for electric lighting from the input-distribution device (ASU) together with power receivers.
Rice. 3.2. Power supply circuit for electric lighting from ASU
On fig. 3.3 shows the power supply circuits for working and evacuation lighting from one single-transformer substation. Lighting shields are fed through separate lines from the substation shield (Fig. 3.3, a) or along a common line with its separation at the entrance to the building (Fig. 3.3, b).
Rice. 3.3. Lighting power supply circuit from a single-transformer
substations
In line cabinets of complete transformer substations, as a rule, protection devices are installed on big values rated currents, therefore, in this case, the lighting installations are powered through the main shields (Fig. 3. 4).
Rice. 3.4. Power supply circuit for group shields from the main shield
Rice. 3.5. Power supply scheme for electric lighting from two single-transformer substations
With a cross-power supply scheme (Fig. 3.5), the working lighting of the room is powered by one transformer, emergency lighting in the same room is powered by another transformer. In order to maintain full lighting during emergency and planned shutdowns of transformers, in some cases it is desirable to have jumpers between single-transformer substations, which ensure that voltage is maintained at the switchboard.
Rice. 3.6. Electric lighting power supply circuit from a two-transformer substation
If there are two-transformer substations in the power supply system of the building, the shields for working and emergency lighting are connected from different transformers (Fig. 3.6). The busbars of the low-voltage switchboard of two-transformer substations are usually divided into 2 sections, according to the number of transformers. A sectional switch is installed between the sections (ATS automatic transfer switch), which allows you to combine both sections into one in case of emergency shutdown of one of the transformers.
For electrical installations of the first reliability category, batteries, generators with diesel or gasoline engines can be used as a second source of emergency lighting, as well as electrical connections with the nearest independent sources (Fig. 3.7).
Rice. 3.7. Power supply scheme for electric lighting from three sources
This scheme is used when lighting installations are powered from three sources.
The power supply of working lighting, as a rule, is carried out by independent lines from the substation shields. At the same time, electricity from the substation is transmitted by supply lines to the lighting main shields, and from them to group lighting shields. Power supply of light sources is carried out from group panels by group lines. Emergency lighting fixtures, including those for continuing work, as well as others, in particular for evacuation, must be connected to an independent power source. The electrical network of lighting installations consists of supply and group lines. Supply lines are performed according to radial, main, as well as radial-main schemes. The choice of the scheme of supply and group networks should be determined by: requirements for the uninterrupted operation of the lighting installation; technical and economic indicators (minimum reduced indicators, consumption of non-ferrous materials and electricity); ease of control and ease of operation of the lighting installation. When choosing the route of the lighting network and installation sites, main and group panels take into account: ease of use (accessibility); exclusion of the possibility of damage in the course of work; aesthetic requirements; reduction in track length. It is not recommended to connect more than 20 incandescent lamps per phase to group lines, and up to 50 lamps when using multi-lamp fluorescent lamps. If a number of electrical receivers are connected to the line along its length, then the current load will decrease with distance from the source. Therefore, electrical lighting networks, based on economic feasibility, are built with a decreasing cross-section of wires in the direction from the power source to electrical receivers. In practice, the cross-sections of lighting networks are calculated under the condition of the lowest consumption of conductor material, The reduced power moment is determined actual losses voltage, After determining the sections, the sections are checked for heating, Estimated current. In the last decade, low-voltage
air networks, made as a self-supporting system of insulated wires (SIP). SIP is used in cities as a mandatory laying, as a highway in rural areas with low population density, branches to consumers. Ways of laying SIP are different: pulling on supports; stretching on the facades of buildings; laying along the facades. The SIP design generally consists of a copper or aluminum conductor stranded core, surrounded by an internal semiconductor screen, then - with XLPE, polyethylene or PVC insulation.
The tightness is provided by powder and compounded tape, on top of which there is a metal screen made of copper or aluminum in the form of spirally laid threads or tape, using extruded lead. On top of the cable armor pad made of paper, PVC, polyethylene, aluminum armor is made in the form of a grid of strips and threads. The outer protection is made of PVC, polyethylene or gel-free blends. The spans of the gasket, calculated taking into account its temperature and wire cross-sections (at least 25 mm2 for mains and 16 mm2 for branches to consumer inputs, 10 mm2 for steel-aluminum wire) range from 40 to 90 m.
Voltages and power supplies. The choice of voltage for the lighting installation is determined by general requirements accepted for the power supply of the facility, as well as electrical safety requirements.
For industrial, public and residential buildings, as well as for open areas, a voltage of no higher than 380/220 V AC with a grounded neutral should be used.
In rooms with increased danger and especially dangerous when used for lighting fixtures with incandescent lamps, a voltage of no higher than 42 V should be used.
Working lighting fixtures and emergency lighting fixtures in industrial and public buildings and in work areas in open spaces should be powered by different independent power sources. It is allowed to supply working and emergency lighting from different transformers of the same transformer substation (TS) when the transformers are powered from different independent sources. In public buildings, in the absence of independent sources, emergency lighting may be powered from a transformer that is not used to power working lighting.
The supply of the external lighting of the object must be separated from the supply of the internal lighting.
Lighting power supply is carried out, as a rule, by independent lines from RU-0.4 kV TP. Typical schemes power supplies for lighting objects are shown in fig. 3.1.
Rice. 3.1. Typical power supply schemes for object lighting:
1 - supply lines;
2 - group lines;
3 - main lighting point;
4 - group lighting shield
Electricity from the transformer substation is transmitted by supply lines to lighting trunk points, and from them to group lighting shields. Direct power supply of light sources is carried out from group shields by group lines.
The lighting power supply scheme and the number of its links are determined mainly by the power required for lighting and the size of the object. In the simplest case, group shields (or a shield) can be fed by lines extending directly from the RU-0.4 kV transformer substation.
Issues of redundant power supply of lighting installations are solved in the complex of the project of power supply of the facility. Two-transformer transformer substations with an ATS device provide the ability to continue lighting operation in the event of an emergency shutdown of one of the transformers.
Feeding and group lines are carried out according to radial, main and mixed schemes (Fig. 3.1). The choice of power scheme is determined by:
Requirements for uninterrupted power supply of lighting installations;
Technical and economic indicators (adjusted costs, consumption of non-ferrous metal and electricity);
Ease of control and ease of operation of the lighting installation.
Feasibility studies have established that the maximum length of three-phase four-wire group lines at a voltage of 380/220 V is no more than 100 m, and two-wire - no more than 40 m. Each group line, as a rule, should contain no more than 20 incandescent lamps per phase, DRL, DRI, DNAT, and when using multi-lamp fluorescent lamps - up to 50 lamps.
Group lines of lighting networks must be protected fuses or circuit breakers for a working current of not more than 25 A. Group lines supplying gas discharge lamps with a power of 125 W or more, incandescent lamps with a power of 500 W or more can be protected by fuses or circuit breakers for a working current of up to 63 A.
Circuit breakers in lighting networks have become more widespread. They are conveniently arranged in a shield, safe to operate, combine the functions of protection and control, operate repeatedly.
In lighting networks, unlike power networks, single-phase electrical receivers are connected to a three-phase circuit. On fig. 3.2 shows three options for distributing lighting lamps between phases in a three-phase circuit.
The upper option is optimal from the point of view of voltage losses in the line, since the centers of gravity of the loads of different phases coincide, but this option is not the best in terms of attenuating illumination ripples and, moreover, if one or two phases are accidentally disconnected, a random distribution of illumination along the line is created.
Rice. 3.2. Phase distribution of lamps
The middle option is the most commonly used. It is better than the others, provides a reduction in illumination pulsations and, when one or two phases are turned off, gives a relatively uniform distribution of illumination along the line.
The lower option is used in cases where the lighting of the room should be switched on in sections.
Group lighting boards (SC) located at the junction of supply and group lines are designed to install protection devices and control group electrical networks.
When choosing a SC, the environmental conditions in the premises, the method of installation, the types and number of devices installed in them are taken into account.
According to the type of protection against external influences, SCs have the following designs:
protected;
closed;
Splash-proof;
dustproof;
Explosion-proof;
Chemically resistant.
ShchO designs allow open installation on walls (columns, structures, etc.) and recessed in wall niches.
The location of the switchgear should be carried out close to the center of electrical loads, while it is necessary to ensure the availability of maintenance of the switchboard. When placing an SC, you should choose rooms with more favorable conditions. environment. SCW should not be placed in hot and damp workshops of the enterprise, as well as in fire hazardous premises. It is forbidden to install SCW in explosive premises.
Group line routing is subject to a number of regulatory requirements and best practices:
Lines should be laid along the shortest possible routes, with open wiring parallel to the walls of the premises, with hidden wiring in the shortest direction;
It is desirable to combine the routes of lines running in the same direction, even if this slightly lengthens the length of the lines;
If possible, lines should be laid along the walls, and not along the ceilings;
Lines laid openly along the ceiling should be laid perpendicular to the side with windows;
The number of passages through walls and the number of junction boxes should be limited;
In rooms with farms, it is advisable to lay lines across farms in the form of transfers between farms;
In fire hazardous premises, it is prohibited to lay transit lines that are not related to the electrical receivers of this premises.
Implementation of lighting networks. Electric lighting networks are being carried out insulated wires, cables, busbars. Wires and cables are used with copper and aluminum conductors, busbars–with aluminum tyres.
Supply lines outdoors are carried out mainly by cables in earthen trenches or cable structures. Overhead lines with bare or insulated (SIP) wires are less commonly used.
Lighting networks inside the premises are carried out by open and hidden electrical wiring. In residential and public buildings, hidden electrical wiring is preferable due to their aesthetics.
The most common methods of open wiring:
Direct laying of wires and cables on walls and ceilings using special mounting hardware;
- laying in perforated steel trays;
- laying in pipes, if necessary, to protect wires and cables from mechanical damage;
- cable wiring, in which the wire (cable) is attached to a pre-tensioned cable (wire);
- wiring by lighting bus duct (SHOS).
busbars used in industrial premises, public and administrative buildings. Busbars SHOS2 and SHOS3 are single-phase, busbars SHOS4 and SHOS5 are three-phase.
SHOS2 and SHOS4 two- and four-wire busbars are used for electrical networks with earthed neutral. The neutral conductor is closed to the metal case of the busbar and forms a combined ( PEN) conductor.
SHOS3 and SHOS5 busbars are made as three- and five-wire. Here, the zero working and zero protective conductors are separated ( N and PEN). Working neutral conductor ( N) is located in the busbar housing, the role of the protective conductor ( REN) performs a metal case.
The ShOS busbar provides the possibility of plug-in connection (without removing voltage from the line) of single-phase receivers of electrical energy for a rated current of up to 10 A.
The bus duct consists of standard elements: sections (straight, introductory, flexible); end caps; plugs and structures for fastening.
Connection of sections demountable and collapsible. One end of the section is provided socket with tightening screws, and at the other end, the protruding bars form a plug. After the plug of one section is inserted into the socket of another section, the plug contact is tightened with screws.