Study of artificial lighting

In public buildings, artificial lighting is recommended to be determined at the beginning of the autumn-winter season, in the evening. Its adequacy is assessed at the workplace using the photometric method (objective lightmetry method) or calculated – using the “watt” method.

The photometric method allows direct measurement of illumination levels using objective lux meters of various modifications (U-116, U-117, Argus-01, etc.).

The device of the light meter and the principle of operation. The U-116 objective light meter consists of a photocell, an arrow galvanometer connected to it, and 4 filter nozzles. The photocell is an iron oxide-free plate on which a layer of selenium is deposited, which in turn is coated with a thin layer of gold or platinum, and on top of it is a protective layer of transparent varnish. For convenience, all this is enclosed in an ebony holder-frame equipped with a frosted glass that protects the photocell from direct sunlight. The conclusions from the iron plate and from the cover gold or platinum film, playing the role of electrodes, are connected to the terminals mounted on an ebonite frame.

The principle of the action of the photocell is as follows: when light rays fall on the receiving part of the photocell in its photoactive layer, selenium (the spectral sensitivity of selenium is close to the spectral sensitivity of the eye), electron emission occurs at the interface with the gold or platinum film ( photoelectric effect), which creates a photocurrent in the external circuit, deflecting the arrow of a galvanometer graduated directly in lux.

The galvanometer of the Yu-116 selenium luxmeter has two scales: up to 30 lux and up to 100 lux. On each scale, the point marks the start of measurements: on scales 0-30, the point is located above mark 5, on scales 0-100, above mark 20. The white plastic nozzle with the letter “K” on the inside is used only with one of the other three nozzles (M, P, T). Without a light meter, illumination can be measured in the range of 5-30 and 17-100 lux. Using KM, КР, КТ nozzles at the same time, they get light filters with light attenuation coefficients equal to 10, 100, 1000, respectively. When you press the right button of the switch to read the readings, use scales 0-100, when you press the left button, scales 0-30 . The illumination level is determined taking into account the attenuation coefficient of the filter nozzle.

In order to protect the selenium photocell from excessive illumination, the measurement should be started by installing the CT (1000) nozzle, and then the KR (100) and KM (10) in series, first pressing the right and then left buttons.

The level of illumination is measured at workplaces, and to obtain an average value of the illumination of a room, measurements are made at 8-10 points with a room area of ​​15-20 m 2 and at 3-4 points in rooms of a smaller area, both under the luminaires and between them .

Note. The light meters are graduated to measure the illumination produced by incandescent lamps, so when measuring

the illumination from fluorescent lamps, it is necessary to introduce corrections: for fluorescent lamps (LD), the correction factor is 0.9, for white lamps (LB) 1.1, for arc mercury lamps (DRL) 1.2, for natural lighting – 0.8.

Recently, digital lux meters have become widespread, which make it possible to measure illumination in the range from 0 to 50,000 lux .

When evaluating artificial lighting, in addition to its quantitative characterization (sufficiency of illumination), qualitative indicators are also taken into account – blindness, direct and reflected luminosity, ripple coefficient, and also uniformity of illumination.

local_offerevent_note August 22, 2019

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