E2S complete product catalogue (v10a) - E2S - #3

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What types and modes of light are available? • Rotating An electric motor drives a parabolic reflector around the light source (halogen) on a vertical axis to create a powerful beam of light travelling through 360º. • Filament & halogen bulb Usually operated with an additional circuit, to give a steady output or more effective blinking output. Filament light bulbs are relatively low cost and give adequate performance, which can be enhanced with a prismatic lens. They have a short life, shortened further by vibration. • Xenon (strobe) tube brilliant flashes of light, which can be enhanced through a freznel lens. The tube life is typically 5 to 8 million flashes after which light output is reduced by approximately 70% • L.E.D. Unlike the filament bulb and the xenon tube, LEDs emit only one frequency of light (i.e. one colour) and cannot yet manage the brightness of a xenon tube. However, they only require a relatively low current and have a very long lifetime, giving an effective solution where an indication or status is required. • Flashing – the light source flashes at regular intervals typically one to three times a second. • Flip Flop – two beacons operating together flash alternatively to give the illusion of light switching from one beacon to the other for a more effective display • Synchronized – the flash of multiple beacons set at the same rate and duration. Controlled by internal circuitry in each beacon. Tube & Bulb life data / information Xenon tube manufacturers all supply tube life data. E2S reports effective life until light output is less than 70%. Halogen and Incandescent Bulb life is harder to predict as there are no industry standards for measurement. Ambient conditions (e.g. voltage & vibration), duty cycles and improper handling can also significantly affect bulb life. How bright is a light? To compare different types of beacon, it may help to understand the three most commonly used measures of intensity. PEAK CANDELA or PEAK CANDLEPOWER. • A unit of luminous intensity used to measure the maximum light intensity generated by a flashing light. Not a measurement the human eye can use to judge brightness. • Doesn’t directly compare two warning lights. CANDELA SECONDS or CANDLEPOWER SECONDS. • Measures the actual light energy contained in a pulse of light added over a period of time. • Used to specify the minimum requirements of light output from a flashing light. • Flash energy is relatively accurate and fair way of comparing radically different types of lights such as incandescent rotators and xenon strobe lights. EFFECTIVE CANDELA or EFFECTIVE CANDLEPOWER. • Based on candela seconds. • Equates the brightness of a flashing light source to the brightness of a steady source. So, if a flashing light has an effective candela rating of 100 then it will be visible at the same distance as a 100 candela steady source. • Predicts the visible range of flashing lights verses steady burn light sources. What’s the best site? All round light dispersion should be the first consideration when installing a beacon. As light travels in straight lines, the beacon will be far more effective if it’s positioned in the line of sight rather than relying on reflections. Other considerations include: • Free air movement needed around the beacon to prevent overheating. • Vibration should be avoided, particularly with filament bulb beacons. • Requirement for impact protection. e.g. lens guard. Some beacons (particularly larger types) emit the light from the side as opposed to the top of the enclosure. If these are wall mounted with the lens 90º to the wall, most of the effective light will be emitted up to the ceiling and down to the floor and not across the area to be covered. The illustration shows the benefits of correct mounting. Beacon effectiveness & range The diagram above illustrates the effective 360¢ªcoverage for beacons in an industrial environment. According to the inverse square law, the intensity of a beacon is reduced by 25% if the viewing distance is doubled How much does lens colour effect the intensity of a light source? Clear Yellow Amber Red Blue Green 100% 86% 51% 15% 12% 15% Please note all the above information is for guidance only and does NOT guarantee performance or coverage. IEC 73 colours These are the colours needed for lights and buttons to conform to the machine directive. • RED – Danger Act Now Danger of live or unguarded moving machinery or essential equipment in protected area. • AMBER – Warning, Proceed with Care Temperature or pressure different from normal level. • GREEN – Safety Precaution: Go Ahead Checks complete, machine about to start. • BLUE – Site Specified Pre-set ready or remote control. • CLEAR – No specific Meaning Could confirm an earlier message. Basics of light Beacons, flash-alarms or strobes are widely used, often to reinforce an audible warning signal. With a wide variety of luminous sources to choose from, selecting the correct one will depend on a number of factors such as the type, brightness, range, situation or operation of the beacon. Useful terms Luminous intensity: symbol, I; unit, candela (cd). Measure of the power of a light source. Sometimes referred to as brightness. Luminous flux: symbol, F; unit, lumen (lm). Measure of the flow or amount of light emitted from a source. Illuminance: symbol, E; unit, lux (lx) or lm/m2. Measure of the amount of light falling on a surface. It is also referred to as illumination. Luminous efficacy: symbol, K; unit, lumen per watt (lm/W). Ratio of luminous flux to electrical power input. It could be thought of as the ‘efficiency’ of the light source. Coefficient of utilization (CU): no unit. The amount of useful light will depend on the lamp output, the reflectors and/or diffusers, position, colour of walls and ceilings, etc. The lighting designer will combine all of these considerations to determine a figure for any lighting calculations. Maintenance factor (MF): Because dirt and ageing can both cause loss of light, it’s useful to take a maintenance factor into account. For example, a new 80W fluorescent lamp with a lumen output of 5700lm falls to 5200lm after 4 months, and remains at that level. The light output has decreased by: 5200 / 5700 = 0.9 This value, 0.9, is the maintenance factor. It should not be allowed to fall below 0.8 by regular cleaning. Optimum distance Gradient 2.5 Joules 5 Joules 10 Joules 15 Joules 35 metres2 20 10 5 2 1 0.5