Advances In Low Level Lighting Design

- Jul 12, 2019-

Attempts to create dimmable LED systems have previously run into many problems, most of which are the result of a mismatch between older line voltage or phase cut dimmer switches and LED circuitry. Dimmer switches that are designed for traditional incandescent lighting may be wholly ineffective for LED dimming. Alternately, they might cause a “dropout” where the illumination dims to a particular level before they drop to no light output, or they might cause LED lamps to emit an audible hum or buzz. The key to avoiding these problems is to integrate LED-specific dimmer technology into an LED system when that system is installed, rather than attempting to use LED lighting with older phase cut dimmers.

Low level LED lighting design starts with consideration of the entire LED system and its circuitry. Unlike incandescent bulbs that will be dimmable with virtually any standard dimmer switch, LED bulbs need to be matched with drivers and transformers that form a coherent system. The LED industry is still developing standards for LED dimming, but until those standards are adopted across the entire industry, an LED bulb from one manufacturer might not dim properly with drivers and transformers from another source. Further, a single LED dimmer can control only a limited number of LED bulbs and fixtures. Designers will need to plan for multiple dimmers to control a lighting application that includes a larger number of bulbs and fixtures. Designers should also consider wireless technology as an alternative for LED dimming.

Currently, pulsed width modulation(PWM) is the most common technology that engineers utilize to dim LED bulbs. When powered on, LED’s almost instantaneously reach maximum lighting. LED dimming problems are resolved when power is rapidly switched on and off and by controlling the ratio of power-on to power-off. Because the human eye cannot detect light pulses above a certain cycling rate, the LED illumination from PWM pulsing appears to be dimmer when the ratio is lower.

When all of this technology comes together, lighting designers will have multiple low level lighting options for many different applications. In residential and commercial applications, for example, low level LED lighting is ideal for inset footpath and floor lighting. Sports and performance arenas can achieve unique high and low illuminated areas. Manufacturing facilities managers can mix and match lighting levels in industrial lighting applications for maximum productivity.