UL 60079-28-2017 pdf download

UL 60079-28-2017 pdf download.Explosive Atmospheres – Part 28: Protection of Equipment and Transmission Systems Using Optical Radiation.
3.8
optical radiation types of protection
3.8.1
Inherently sale optical radiation _op Is”
visible or infrared radiation that is incapable of producing sufficient energy under normal or specified fauh conditions to ignite a specific explosive atmosphere
Note I to entry: This clelinition is analogous to the term intivleically sat& applied to elecincal cfrcii*s.
3.8.2
protected optical radiation
“op pr’
visible or infrared radiation that is confined inside optical fibre or other transmission medium under normal constructions or constructions with additional mechanical protection based on the assumption that there is no escape of radiation from the confinement
3.8.3
optical system with Interlock
“op sW’
system to confine visible or infrared radiation inside optical fibre or other transmission medium with interlock cut-off provided to reliably reduce the unconfined beam strength to safe levels within a specified time in case the confinement fails and the radiation becomes unconfined
3.9
Irradlance
DEPRECATED: intensity
radiant power incident on an element of a surface divided by the area of that element
[SOURCE: IEC 60050-731:1991, 731 -1-251
3.10
light (or visible radiation)
optical radiation capable of causing a visual sensation directly on a human being
Note 1 to entry NOnWtaJtY coverwtg the wavebnglh m vaaasn range of 3O nm to 800 nm.
Note 210 entrt,: In the law aid optical corNnunicati tields, custom and ptaclloe th the EnØah language have extended usage of the tami bi4 to inide the much broader ponion of the eleclromagnebc spectrum that cat be handled by th. basic optical techniques used for the visible spectrum.
[SOURCE: IEC 60050-731:1991, 731-01-04]
3.11
optical fibre
filament shaped optical waveguide made of dielectric materials
[SOURCE: IEC 60050-731 :1991, 731-02-01])
5.2.2.2 Optical power
If compliance with Table 2, Table 3 or Table 4 is to be based on maximum optical power values, then maximum optical power shall be measured In accordance with one of the following test methods, using the same or equivalent thermal dissipation conditions as In the intended application:
1) The actual driver circuitry is used to power the optical device, with maximum optical power measured under fault conditions in accordance with the over-power / energy fault protection criteria according to 5.2.5 and the respective EPL at ambient temperature between 21 °C and 25 °C. If the optical power is higher at the foreseen ambient temperature range of the equipment, the measured value at room temperature shall be adjusted according to the temperature coefficient taken from the data sheet. If no information is given in the data sheet Then the measurement shall be done additionally in the lowest and highest values of the temperature range specified for the equipment. Separate samples shall be taken for each of the 3 tests If the optical device is subjected to input parameters which are higher than its maximum rating. The number of test samples depends upon the number of fault conditions to be applied.
2) The maximum input parameters to the optical device from the actual driver circuitry are calculated based on analysis of the driver circuitry schematic, This analysis shall include consideration of fault conditions in accordance with the over-power / energy fault protection criteria according to 5.2.5 and the respective EPL One test sample of the optical device without the driver circuitry Is then connected to a separate vanable source of supply and subjected to input parameters equal to the maximum calculated input parameter values. Maximum optical power is measured with the optical device at ambient temperature between 21 °C and 25 °C. lithe optical power is higher at the foreseen ambient temperature range of the equipment, the measured value at room temperature shall be adjusted due to the temperature coefficient taken from the data sheet. If no information is given in the data sheet then the measurement shall be done additionally in the lowest and highest values of the temperature range specified for the equipment. Separate samples shall be taken for each of the 3 tests if the optical device is subjected to input parameters which are higher than its maximum rating.
3) The actual driver circuitry Is replaced with a separate variable source of supply. This source of supply
is then used to provide vanable inputs to the optical device, with maximum optical power measured. No faults are considered. Ten samples of the optical device are to be tested at ambient temperature between 21 C and 25 °C. The maximum optical power Is then taken from the highest power that can be measured at the ten samples before the optical devce shuts down or folds back.