No light, no safety, no automation

In industry light plays a central role in many domains, not just for lighting premises

By Morand Fachot

Lighting fulfils a growing range of tasks in the industrial environment, improving safety and enabling automation in many areas

storage lighting osram New lighting storage areas systems are now energy efficient (Photo: Osram)

Human safety first

Lighting in the industrial environment often evokes little more than a vision of a drab setting. This is no longer the case everywhere, in particular in modern factories.

The industrial environment is likely to be full of potential hazards for the humans working within it. Lighting has always been important in ensuring workers have a clear view of the equipment they operate and of their surroundings.

IEC Technical Committee (TC) 34: Lamps and related equipment, develops International Standards for these lighting installations, including new technologies such as LEDs or OLEDs (organic LEDs), as well as for lighting systems used in some safety systems.

Lighting use in industry has moved beyond a mere "passive" role to a more active one with lighting systems, often in combination with a variety of sensors, becoming ever more important in ensuring a safer working environment.

A major risk in highly-automated sectors using machines and robots, in particular, is to keep humans away from a machine's or robot's work envelope. For this, passive measures such as external physical barriers (a secure fence or enclosure) around the workstation are the first line of defence. However, if this line is breached, safety rests on a variety of sensors for the detection of a human presence in a restricted or dangerous location.

Among these sensors, some of the most important are light curtains which consist of photoelectric barriers of several aligned beams between emitting and receiving columns. Interrupting a single beam will trigger the emergency stop for any machine. Different resolutions permit intrusion of a finger, hand, limb or body. These photoelectric sensors can also detect the presence of an unauthorized individual in the restricted zone.

Other lighting/optical safety devices include optical zero-force touch switches, which provide low impact machine control, or single beam photoelectric safety sensors for protecting small openings or large areas.

IEC International Standards for electro-sensitive protective equipment apply to these devices. These are developed by IEC TC 44: Safety of machinery – Electrotechnical aspects. They include International Standards for electro-sensitive protective equipment using active opto-electronic protective devices, vision-based protective devices or passive infra-red protective devices.

Machine safety matters too

Making sure that machines are not damaged is essential in ensuring they operate smoothly and, more importantly, that operators are not hurt. Warning lighting systems connected to the machines or to sensors installed on these provide indications about equipment condition and operation.

Stack lights (also called light bars or tower lights) are used in similar applications as beacon lights/strobes, to display information regarding machine/process conditions. They have colour-coded indicator segments stacked on top of one another. A stack light will typically have up to five differently coloured segments, including, as a minimum: red, showing failure conditions, yellow, warning of conditions such as over-temperature or over-pressure and green, indicating normal machine or process conditions.

Better products, higher productivity

Lighting systems have undoubtedly made a major contribution to advances in automation at all stages.

The detection of defective components or unwanted and contaminated raw material (such as the presence of stones or damaged grains) in large quantities of rice, corn or wheat relies increasingly on optical machines that detect flaws with special lighting, often using LED-based lamps, in fully or partly automated processes.

Finding, precise positioning or identification of objects or rotating axes in factory-automated production processes relies on sensors, many of which depend on a variety of lighting sources that include LEDs or lasers.

International Standards for fibre optic sensor systems are prepared by IEC Subcommittee (SC) 86C: Fibre optic systems and active devices (see article on IEC SC 86C in this e-tech). IEC TC 76: Optical radiation safety and laser equipment, develops International Standards for equipment using laser as well as LED-based lights.

Laser sensors are particularly useful for making precise measurement of dimensions such as thickness, diameter, height and distance to carry out difficult distance-based applications such as filling containers or handling objects of the same colour – for example, black foam on black plastic, black rubber in front of metal or multicolour packaging and targets.

Proper and safe lighting conditions not only rely on IEC International Standards, but also on two IEC Conformity Assessment (CA) systems, IECEE and IECQ. IECEE (IEC System of Conformity Assessment Schemes for Electrotechnical Equipment and Components) provides a global platform for testing and certifying lighting products (see article on IECEE CA for lighting products in January/February 2015 e-tech). For its part, IECQ (IEC Quality Assessment System for Electronic Components) has introduced the IECQ LED initiative (see article on IECQ CA for LED lighting solutions in January/February 2015 e-tech).

No lighting in industry without IEC standardization and CA work

Nowadays, staff safety, plant reliability and proper operation, higher productivity and enhanced quality of products rely to a great extent on a multitude of components and systems based on lighting.

The importance of lighting in industry, and in automation in particular, is set to expand further in the future, owing in no small part to International Standards prepared by a number of IEC TCs and to IEC CA systems that provide assurance that they comply with international technical and regulatory requirements.

Patlite ex-stacklight Stacklights give indications on equipment condition/operation (Photo: PATLITE)
light curtain Safety light curtains switch off machinery if workers get too close
storage lighting osram New lighting storage areas systems are now energy efficient (Photo: Osram)