Computation of industrial illumination

In most of cases a computation of industrial illumination is fulfilled for use method of light flux. For this method a light flux of one lamp F_л (in lumens) is determined by formula:

,

where Е_н is aillumination norm for departments, workshops, laboratories, that are designing (Tab. 4.4 [6]); S is a room area in m²; k is assurance factor of light flux: for luminescent lamps at small apportionment f the dust, smoke, soot - 1,5; at middle and big apportionment -1,8 and 2,0 accordingly;

for incandescent lamps at small apportionment of the dust, smoke, soot - 1,3; at middle and to big - 1,5 and 1,7 accordingly; Z is acoefficientdefinedas Е_СР/Е_Н, for most advantageous lamps disposition, when a light flux is used for illumination of work zone most rationally, equal to 1,1…1,2; n is a number of lamps in workplace; h - coefficient of light flux use from lamp, which shows what part of light lamp flux F reaches the surfaces, that is enlightened, in that number due to reflection of light flux from walls, ceiling and work surface.

Coefficient h depends on geometrical workplace dimensions j, coefficients of walls reflection L_ρc, ceilings L_ρп and workplaces L_ρp, and calculated for different lamps types - tab. 2.2 in [9].

Workplace index

j = ,

where A and B - length and width of the workplace, that is enlightened, m; h_p is a lamp height over work surface, m.

For calculated light lamp flux F_Л power of one lamp may be determined [9, tab. 2.3] and disposition of lamps n on workplace and lightings.

Problem: To calculate the general illumination of area for inspection on defects of aircraft engine units, where an illumination standard for application of luminescent lamps with degree I_Г puts together 400 luxes. Apartment dimensions are following: A = 35 m, B = 12 m, Н = 4,0 m.. It is supposed to use light fittings of type ШОД with lamps ЛД, height of fitting over working surface h_р = 3,25 m, supply coefficient k is equal to 1,5 (as for apartments with small apportionment of dust, smoke and soot) lace.

j = .

Making up reflection coefficients for ceiling r_п = 0,7, walls r_с = 0,1 and spotlighted surface r_р = 0,1 in special tables [9] one may find coefficient of light stream use of the light fitting h= 0,59. Correction coefficient Z is equal to 1,1.

Further computation can be followed with determination of necessary light stream of one lamp, if amount of light fittings and lamps in them is known, or with determination of amount of light fittings and lamps, if a type and lamps power is known.

If in example it is supposed to use light fittings of type with lamps of ШОД type ЛД 2x80, F_л= 3440 luxes (in tab. 2.3 [9]), so a number of lamps will be found from expression

.

A number of lamps N will put together

.

Lamps must be disposed uniformly in six rows, 8 in each row.