Specifying LED Lighting Solutions for Industrial Environments

By Jeff Shepard

Contributed By Digi-Key's North American Editors

Lighting is a critical element in designing safe, efficient, and cost-effective industrial environments across various activities, including logistics, machine operation, control cabinets, work stations, and manufacturing lines. In a growing number of instances, LEDs can provide superior lighting solutions. Compared with traditional fluorescent, metal halide, high-pressure sodium, and other lighting technologies, LED fixtures are more energy-efficient, reducing operating costs, and are longer-lasting, reducing maintenance costs. Industrial luminaires are often used in challenging environments and can be required to include ingress protection and specified levels of power quality, in addition to supporting occupational safety and sanitation. Balancing these diverse requirements complicates the luminaire selection process.

This article reviews performance metrics including lumens, wattage, efficacy, lux, zonal lumen distribution, correlated color temperature, color rendering index, rated lifetime, and costs associated with industrial luminaires, with a special focus on LEDs. It then details environmental considerations, including ingress protection requirements, total harmonic distortion, and power quality demands, and lighting for hazardous environments.  Finally, the article closes by presenting specific solutions from Banner Engineering for lighting in pick-to-light systems, forklift guidance, and general illumination in work stations, machine lighting, and control cabinets (Figure 1).

Image of LED luminaires are available in a range of formatsFigure 1: LED luminaires are available in a range of formats optimized for a wide variety of applications. (Image source: Banner Engineering)

Performance metrics

Specifying the illumination level is the basis for selecting the optimal luminaire for a given application. There are numerous metrics to consider ranging from the operating efficiency of the luminaire to how well it mimics standard white light. It begins with a single candle or candela (Cd). The Cd is a base SI unit that measures the luminous intensity of visible light emitted by a specific source (standard candle) in a specific direction. Building on the concept of a Cd, important metrics for comparing luminaires include:

  • Lumen (lm) – Luminous flux equal to the light emitted in a unit solid angle by a uniform point source of one Cd, taking into account light output in all directions.
  • Watts (W) – Consumption of electric power: for DC circuits, W = VDC x amps; for AC circuits, W = VRMS x amps.
  • Efficacy (lm/W) – How efficiently a light source produces visible light.
  • Lux (lm/m2) – Intensity of light that hits a surface as perceived by the human eye.
  • Zonal Lumen Distribution – Distribution of lumens emitted by a luminaire in zones in discrete vertical planes. Used to determine a luminaire’s spacing requirements.
  • Correlated Color Temperature (CCT) – Temperature, in degrees Kelvin (K), of a blackbody radiator with a chromaticity equal to the light source. The CCT of white light ranges from 2700K to 6500K.
  • Color Rendering Index (CRI) – Ability of a light source to reveal the colors of various objects faithfully in comparison with an ideal or natural light source. CRIs range from 0 to 100. Incandescent bulbs have a CRI of 100, LEDs have CRIs ranging from 80 to 90+.

As lighting technologies have evolved, the process of specifying the optimal solution has become more complicated. For example, the efficacy of LEDs is substantially higher than the efficacies of fluorescents and high-intensity discharge (HID) lamps. While fluorescents and HIDs emit light in all directions, LEDs are directional. The bottom line is that the metrics are most useful for comparing LEDs to LEDs, fluorescents to fluorescents, and so on. To compare differing lighting technologies, users often need to evaluate samples side-by-side to determine which is the best.

In addition to the quality of the light produced, users need to be aware of the total harmonic distortion (THD) and power factor (PF) of the ballast or driver powering the luminaire. THD is a measure of the distortion of the electrical current coming into an electronic power converter. Lower THD means lower peak currents and greater efficiencies in the electricity distribution network in a building and reduced demand on the local utility. IEEE 519-2014 is a helpful reference for understanding harmonics and applying harmonic limits in power systems. THDs of 20% or less are usually required. PF is an equally important metric. A load (ballast or driver) with a low PF draws more current than a load with a high PF for equal output power. PF is a dimensionless number between 0 and 1. Ballasts and drivers should have PFs of at least 0.9.

Lifetime and cost considerations

LEDs generally have lifetimes greater than 25,000 hours, but their efficacy and brightness decline as they age. The lifetime of LED luminaires is based on the number of hours it takes to drop to 70% of the initial light output and is called the L70 parameter. Non-LED lighting technologies suffer catastrophic failures at some point; their lifetimes are defined as the number of hours of operation at which 50% of the units are expected to have failed. Non-LED technologies also experience declines in lumen values as they age. Called lamp lumen depreciation (LLD), this effect varies between lighting technologies (Table 1).

Lighting Technology Rated Lifetime (hours) Lamp Lumen Depreciation (LLD) at end of rated life
Halogen Incandescent 3,000 to 5,000 5%
Linear Fluorescent 15,000 to 45,000 10%
High Pressure Sodium 15,000 to 40,000 30%
LED 20,000 to 50,000+ N/A

Table 1: Lamp lumen depreciation and rated lifetimes comparison. (Table source: Banner Engineering)

To compare the cost of lighting technologies, users need to consider the initial labor and equipment cost plus the energy, maintenance labor, and equipment costs over the lifetime of the luminaire (Figure 2). The initial labor and equipment costs can be overcome by increased energy efficiency and lower maintenance needs, and longer-lasting and more efficient LEDs can produce significant lifetime savings.

Graph of lighting cost comparison based on 15-year lifecycleFigure 2: Lighting cost comparison based on 15-year lifecycle. (Image source: Banner Engineering)

Environmental requirements

Luminaires used in industrial facilities need to be designed to withstand hazardous conditions. The National Electrical Code defines three types of hazardous locations:

  • Class I – flammable gasses or vapors
  • Class II – combustible dust
  • Class III – easily ignitable fibers or flyings

U.S. Federal regulations require: “equipment shall be marked to show the class, group and operating temperature or temperature range, based on operating in a 40°C ambient temperature for which it is approved.”

Ingress protection (IP) ratings are important and are indicated by two numerals. The first describes the resistance of the equipment to solid foreign objects, such as dust, the second describes the degree of protection against water. Luminaries rated IP67 are dust and water-resistant, making them suited for many industrial environments, and they can withstand short-term immersion in water. Luminaires rated IP68g provide additional protection and are more resistant to oil and water penetration.

Vibration and extreme temperatures are often found in industrial environments. The thin filaments, delicate components, and glass envelopes used with some lighting technologies can be especially vulnerable to damage from vibration. LEDs do not have delicate components and are much more resistant to vibration and impact. While they are mechanically rugged, high ambient temperatures tend to reduce the efficacy and lifetime of LEDs. On the other hand, compared with other lighting technologies, LEDs are better-suited to refrigerated warehouses and other facilities where temperatures down to -40°C are found.

Luminaires for pick-to-light

Pick-to-light systems can reduce the costs of warehouse picking operations through increased efficiency, productivity, and accuracy. For pick-to-light installations, Banner offers the EZ-LIGHT® K50L series, including the K50LGRASXPQ (Figure 3). K50L luminaires are offered with one LED (green), two LEDs (green and red), or three LEDs (green, red, and yellow), depending on the model, and they are vibration-resistant. The K50LGRASXPQ offers green and red LED lighting plus a multiple tone audible alarm. Features of the K50L series include:

  • Easy to install with bright LED indicators and audible alarm
  • Rugged and fully sealed. Rated at IP67 or IP69K per DIN 40050-9, depending on model
  • No external controller is needed for these self-contained luminaires
  • Immunity to radio frequency interference (RFI) and electromagnetic interference (EMI)
  • The audible alarm on IP67 models has an adjustable intensity that can be continuous or staccato
  • Flexible installation with inputs from 12 VDC to 30 VDC and protection against reverse polarities

Image of Banner Engineering K50 series pick-to-light luminairesFigure 3: Banner Engineering K50 series pick-to-light luminaires are DC-operated with steady or staccato sound indication and a choice of 1, 2, or 3 colored LED indicators, depending on the model. (Image source: Banner Engineering)

Forklift guidance luminaires and sensors

Forklift drivers can have obstructed views, requiring them to dismount multiple times when placing difficult loads. The efficiency of material handling operations can be increased through the use of forklift guidance luminaires and sensors. For example, the model WLS27PXRGBW285DSQ luminaire from Banner is part of the WLS27 Pro series and is 285 mm long, has IP66, IP67, and IP69K environmental ratings, and includes red, green, blue, and white LEDs (Figure 4).

Image of Banner luminaire includes red, green, blue, and white LEDsFigure 4: This 285 mm long luminaire includes red, green, blue, and white LEDs and can be used for forklift guidance. It has IP66, IP67, and IP69K environmental ratings. (Image source: Banner Engineering)

All luminaires in the WLS27 Pro series can display multicolor animations at varying speeds and patterns and be segmented, making them well suited to forklift guidance systems. With shatterproof copolyester housings in aluminum frames, WLS27 Pro units are resistant to breakage and impact. Their IP69K rating enables them to operate during harsh washdowns and in outdoor environments. Integrated timer and counter functions allow them to display time or quantity information, including distance and position, using pulsed signaling.

WLS27 Pro luminaires can be combined with the Q5X multi-function laser sensor to implement forklift guidance systems (Figure 5). The Q5X has a range from 50 mm to 5 m. Other features include:

  • Reliable detection of clear and reflective objects, multicolor targets, black targets against a shiny metallic background, black targets against a black background, and dark objects (<0.1% reflective black targets)
  • Dual teach mode measures both light intensity and distance
  • 270-degree rotatable to meet a variety of mounting constraints
  • Programmable via IO-link, remote teach, onboard user interface, or optional remote sensor display

Image of Q5X multi-function laser sensor from Banner EngineeringFigure 5: Multi-function laser sensors like the Q5X from Banner Engineering can be used to implement forklift guidance systems. (Image: Banner Engineering)

General illumination options

Banner’s WLB32ZC285PBQMB is a 285 mm long ultra-bright LED fixture that features an even light output of 750 lm with a no-glare ‘glow’ (Figure 6). It’s part of the WLB32 family, which includes fixtures from 285 to 1130 mm long with illumination ratings from 750 to 3000 lm. These luminaires are designed in workstations, machine lighting, control cabinets, and manufacturing lines.

Image of Banner’s model WLB32ZC285PBQMB ultra-bright LED bar lightFigure 6: Banner’s model WLB32ZC285PBQMB is a 285 mm long ultra-bright LED bar light for general illumination needs. (Image: Banner Engineering)

WLB32 light bars are available that can form a continuous length of lighting by "daisy-chaining” with a minimum of wiring while maintaining independent operation of each light bar. Other features include:

  • High/Low/Off switch
  • Shatterproof window and metal housing
  • Flexible installation with magnetic or angle brackets or snap clips
  • Eyeshield block side glare on some models
  • Motion detection on some models

Summary

There is a wide range of performance, cost, and environmental factors to consider when specifying industrial lighting solutions. In a growing number of cases, LED luminaires are an attractive option. Compared with traditional lighting technologies, LED fixtures offer greater lighting flexibility and reliability, and LEDs deliver higher energy efficiency, longer lifetimes, and lower maintenance needs. As a result, while the initial installation costs of LEDs can be greater than other lighting technologies, LEDs offer lower lifetime costs, in addition to superior lighting solutions.

Disclaimer: The opinions, beliefs, and viewpoints expressed by the various authors and/or forum participants on this website do not necessarily reflect the opinions, beliefs, and viewpoints of Digi-Key Electronics or official policies of Digi-Key Electronics.

About this author

Jeff Shepard

Jeff has been writing about power electronics, electronic components, and other technology topics for over 30 years. He started writing about power electronics as a Senior Editor at EETimes. He subsequently founded Powertechniques, a power electronics design magazine, and later founded Darnell Group, a global power electronics research and publishing firm. Among its activities, Darnell Group published PowerPulse.net, which provided daily news for the global power electronics engineering community. He is the author of a switch-mode power supply text book, titled “Power Supplies,” published by the Reston division of Prentice Hall.

Jeff also co-founded Jeta Power Systems, a maker of high-wattage switching power supplies, which was acquired by Computer Products. Jeff is also an inventor, having his name is on 17 U.S. patents in the fields of thermal energy harvesting and optical metamaterials and is an industry source and frequent speaker on global trends in power electronics. He has a Masters Degree in Quantitative Methods and Mathematics from the University of California.

About this publisher

Digi-Key's North American Editors