Lighting electric units
Lighting electric units are called the special electrotechnical devices intended for lighting of territories, rooms, buildings and constructions.
Lighting electric units are the necessary element of modern houses, institutions, public and manufacturing enterprises and represent the difficult complexes consisting of distributing devices, the high-level and group power supply networks, different electroadjusting devices, lighting fixtures, light sources and also the fixing, supporting and protective designs.
Distinctive feature of lighting electric units is the variety of the applied schemes and ways of execution of electroconductings, designs of lamps and other light sources. In modern powerful electric units difficult devices of automatic equipment and telecontrol are used. Depending on assignment of the light source distinguish the general, the local, combined, working and emergency light.
The general is called illumination of everything or parts of the room. Illumination of jobs, objects or surfaces, for example, special lighting of the processed part or the tool on the lathe is local. Combined combines the general and local lighting. The worker call the lighting serving for ensuring normal activity of production and auxiliary divisions of the enterprise.
Lighting which at violation of the working light temporarily provides the possibility of further work or evacuation of people is called emergency. Emergency lighting is located in production rooms, corridors, on staircases.
Lamps of emergency lighting have to differ from other lamps in coloring and the design and to join the power supply network which is not connected with network of the working light.
Power supply of lamps of the general, local, working and emergency consecrations in normal rooms is carried out with tension of 127 and 220 V, and in rooms with the increased danger and in especially dangerous — with tension 12, 24, 36 Century.
Distinguish also lighting figurative, security, svetoograditelny. Figurative lighting is carried out by portable manual lamps from networks 127 or 220 V in normal rooms and from network of 12 V in rooms of the increased danger and on open sites of the territory of the enterprise. Security lighting is established along the fencing of the protected territory so that the external and internal zones adjoining directly the fencing were at the same time lit.
Svetoograditelny lighting is established on high buildings and other constructions for safety of flights of airplanes in night-time. The main requirement imposed to lighting is ensuring the normalized illumination parameters which are defined by working conditions, including: the sizes of surrounding objects, the opportunity to distinguish them, their contrast with the background and the reflectivity of the background; availability of objects, available, dangerous to touch, and also availability of the shining surfaces of big brightness (at electro-or gas welding, metal melting).
Level of illumination of certain sites of rooms or jobs increase by means of regular arrangement of lamps of the general lighting, the device of spot lighting, use of structurally more perfect lamps or increase in power of lamps.
Observance when mounting lighting electric units of the normalized parameters of illumination promotes improvement of conditions, increase in labor productivity and quality of the produced products, decrease in fatigue of workers, power saving. Rational, economical use of electrical energy and cutting of costs for lighting for which 10-12% of all developed electric power are spent is the big economic task.
Mounting of lighting electric units is made according to the standard in which lighting calculations and calculation of lighting network are given. Requirements to production of mounting of electric units, its norms and rules are established PUE and Construction Norms and Regulations and also mounting instructions of manufacturers of electric equipment, wiring devices and products. When mounting lighting electric units the nature of technology process, operating conditions and state of environment have to be considered.
Calculation of losses of tension is conducted on condition of the minimum expenses of conduction materials.
When calculating required sections of wires in the metallic circuit tension of the source of the electric power (generator), distance from it to loading, tension on loading clips, necessary for normal operation of receivers of the electric power, and the current intensity or power of loading are usually known.
In most cases the current intensity of loading is changeable, that is there are corresponding changes of loss of tension, for this reason it is necessary to calculate voltage deviation on energy receiver clips from rated value at the maximum and minimum loadings.
According to PUE in power networks (including alternating current mains) inconsequential losses of tension on the line from the power source to the most remote point of network at the standard duty should not exceed 5%, tension of the most remote lighting lamps of residential buildings should not decrease more than 5% (as at the same time the luminous flux of these lamps decreases by 18%), and lamps of the industrial enterprises and public buildings – more than 2,5% of their rated voltage.
The design load of the feeding lighting network is defined by the work of the rated capacity of lamps determined by lighting calculation and coefficient of demand equal 0,6 for distributing devices, substations, warehouse and auxiliary premises of the enterprises; 0,8 — for laboratories and medical institutions; 1 — for production rooms.
The power supply of lighting electric units is carried out from separate lighting transformers or from transformers to which also power consumers are at the same time attached (electric motors, electrowelding machines).
At the insufficient illumination of production workshops the sight worsens and the labor productivity falls, the quality of products decreases. Therefore for the industrial enterprises are developed and standards of the minimum illumination, the provided Construction Norms and Regulations and PUE are obligatory.
Illumination sizes on these norms depend on the nature of production and subjects they are higher, than big accuracy is required when performing technology processes and production operations. At design and lighting calculations illumination is accepted a little big, than it is required on norms.
This stock is caused the fact that during operation the level of initial (design) illumination inevitably decreases eventually. It occurs due to gradual reduction of the luminous flux of lamps, pollution of the armature and some other reasons.
However the stock of illumination accepted at design and calculations is sufficient at normal operation of electric lighting installations: to regular cleaning of lamps, light guides, timely change of lamps, etc. At unsatisfactory operation the accepted stock of illumination cannot compensate the going-down illumination level, and it becomes insufficient.
It must be kept in mind that on room illumination the great influence is exerted by color of coloring of walls and ceilings and their state. Coloring in light tone and regular cleaning of pollution promote ensuring required norms of illumination. Frequency of surveys of lighting electric units depends on character of rooms, state of environment and is established by the chief power engineer of the enterprise.
Approximately for dusty rooms with hostile environment it is possible to accept necessary frequency of surveys of the working light once in two months, and in rooms with the normal environment – once in four months. For installations of emergency lighting terms of surveys cut by half.
Surveys of lighting installations
At surveys of lighting electric units check the condition of the electrical wiring, guards, lighting instruments, automatic machines, switches, plug adapters and other elements of installation. Check also reliability of the contacts which are available in installation: the weakened contacts have to be tightened, and burned — are smoothed out or replaced by new.
Replacement of lamps in lamps
In production workshops of the industrial enterprises there are two ways of change of lamps: individual and group. At the individual way of the lamp replace in process of their failure; at the group way they are replaced with groups after they served the put number of hours. The second way economically more favorable as it can be combined with cleaning of lamps, but is connected with the big expense of lamps
When replacing it is not necessary to use lamps of bigger power, than it is allowed for lighting instrument. The overestimated power of lamps leads to inadmissible overheating of lamps and cartridges and worsens the condition of isolation of wires.
Lamps and fittings are cleaned from dust and the soot in workshops with small release of pollutants (mechanical and tool shops, machine halls, tanning for waters, etc.) by two times a month; at big release of pollutants (forge and foundry workshops, spinning mills, cement works, mills, etc.) – four times a month. Clean all elements of lamps — reflectors, diffusers, lamps and the outside surfaces of fittings. Cleaning of windows for natural lighting is carried out in process of their pollution.Top