Monday, May 01, 2017

LED Lighting for Broadcast in 2017: Rethinking Power and Control in the Broadcast Setting

It has been nearly two decades since scientists and engineers first experimented with the light emitting diode (LED) as a high output light source. Back then, I was designing broadcast studios with an interesting twist that had recently come of age: the first round of fluorescent fixtures equipped with high CRI lamps.  What great color, and what a great addition to the designer's palette!  I thought I had seen broadcast lighting’s full evolution.
But there was more to come.  Now, in 2017, it's LED lighting sources that have fully come of age in the broadcast industry. LED’s are becoming the standard for television lighting just as they have already become standard in domestic lighting. I have watched manufacturers develop cost-effective LED fixtures to replace incandescent and even those fluorescent sources in every conceivable aspect of production lighting. I have seen firsthand how broadcast studios can reap the myriad benefits of this remarkable technology. But in doing so, broadcast professionals must be prepared to approach powering and controlling these fixtures in new ways and create a different infrastructure within their studios.
In this article, I'm going to cover the Why, the What, and the How you need to know if you plan to take advantage of the creative potential and operational economy of LEDs.
LED fixtures have overcome the color and energy deficiencies of incandescent light sources. Whereas incandescent fixtures shift color temperature as they are dimmed, LED fixtures can provide the constant color temperature vital to image quality. More importantly, LED’s typically use eighty percent less power and generate less heat than incandescent lamps. Since many broadcasters use production lighting for 80 hours, or more, per week, this efficiency significantly reduces costs from direct energy consumption as well as collateral consumption required for air-conditioning. In terms of lifespan, the LED’s life expectancy of up to 50,000 hours – compared to roughly 1,000 hours for an incandescent – also brings significant savings as the operational expense associated with lamp replacement is dramatically reduced.
Manufacturers of broadcast lighting instruments have seized upon this major shift in technology, and are producing a wide variety of equipment to deliver high-quality light for every aspect of television production. These innovations have brought a renewed excitement to the lighting industry as designers now have ever greater flexibility within their designs. Designers can take advantage of LED fresnels, ellipsoidals, strip lights, softlights, pars, moving heads, large sources or small sources to achieve a signature look for sets and talent. These fixtures also provide far more functionality than any incandescent ever could.  Want to change color?  Go ahead – no ladders needed.
But LED technology differs from Edison’s life-changing invention in many important ways. As the broadcast industry embraces this technology and its full functionality, lighting professionals must understand how LED’s are changing the nature of production studio infrastructure.
Start with dimming and power distribution. In a career spanning nearly four decades, I have designed more broadcast studios than I can count. Almost every one included dozens, if not hundreds of dimmers spread across multiple dimmer racks. Even the most efficient of these still demanded enormous power. Now, LED’s are making traditional dimmers obsolete. The vast majority of LED sources for broadcast have their light output intensity controlled via onboard digital dimming. The hardware and software to accomplish this are located within the instrument itself. But while dimmer racks are not needed to control light output intensity, there is still a need to control the power that is energizing the fixture. Considering that the instrument has a “brain” onboard, it is still important to have the ability to turn the 120v power off and on, so the hardware is not idling when not in operation drawing quiescent current like the clock on your old VCR.
Additionally, LED’s have unique power requirements. For instance, in the first few milliseconds of energization, LED hardware has a sudden, intense electrical draw that can sometimes be as high as thirty times its normal operating amperage. This "in-rush" current can have a profound effect on the main electrical feed that is supplying power to the panels and is often enough to trip a main breaker. For this reason, it is important to sequence the energization of the individual branch circuits. 
This is why relay panels are now integral in broadcast lighting. They allow the raw 120v power to the instrument to be turned on and off via DMX control sequencing individual circuit energization, thereby avoiding the momentary - but very real - stress of in-rush current.
Just as LED’s are changing the power infrastructure in broadcast studios, they are also revolutionizing the control infrastructure. Due to the onboard functionality of LED’s – including dimming, color control, and other features – the control console now must be directly connected (hardwired or wireless) to each fixture. This is the same direct connection that has been used since the inception of moving lights to control functions such as color, pattern, beam shape, focus, pan, and tilt. But this direct control is relatively new in a world that is used to fresnels, softlights, cyc lights and ellipsoidals. Thus it requires some rethinking of how control signals are distributed.
A low voltage control infrastructure using DMX (the standard lighting control protocol) is now the primary way a broadcast studio lighting scheme is controlled. One can simply plug in a control console on one end of a DMX cable and a lighting fixture on the other, set the DMX channel on the light and control that channel via the console. DMX allows control of the numerous attributes that now reside within most LED fixtures. Most, if not all, of these fixtures also have the ability to be cabled in a daisy chain fashion for both DMX control and 120v power. By stringing fixtures together, a number of instruments can be controlled and powered from a single DMX output and 120v receptacle. This lessens the numbers of outputs and receptacles needed on a lighting grid to properly control all fixtures.
Two methods have become prominent in properly distributing DMX around a broadcast studio. The first is a hardwired infrastructure that utilizes opto-splitters which act as repeaters of the control signal.  The opto-splitter has input ports which receive the DMX signal from the control console. It then repeats this signal through multiple outputs, which are connected to DMX output receptacles around the studio. Fixtures can plug into these outputs, and then conveniently pass the DMX signal onto other fixtures via daisy chain. 
The other prominent method for distributing the DMX control signal is through a network scheme. This is accomplished by running ethernet cables from a network switch (POE type) to locations similar to a pure DMX infrastructure. RJ-45 receptacles are located similarly to the 5-pin DMX receptacles mentioned above and connected back to the network switch. A DMX interpreter, or gateway, is connected to the RJ-45 receptacle and serves to convert RJ-45 based DMX signal back to a standard DMX arrangement used in both the console and the fixtures.
Like you, much of my career and that of my clients’ was spent on a ladder. There was always a lamp to change or color to swap out. Long-life lamps and fluorescent sources may have cut down on that ladder-time, but often at the expense of color or limited control. Broadcast lighting technology now offers a host of LED options for any design challenge. And as LED’s continue to improve, they will only become more indispensable. Fueled by generous incentives from utility companies (a topic I'll cover at another time), more and more facilities are taking advantage of the scalability of LEDs. From the most elaborate to the simplest of systems, LEDs invite expansion, inspire creativity, and control budgets. Broadcast lighting has come of age; all that's needed to take advantage of them is know-how.

Bill Capps is a senior systems integrator with Barbizon Light of New England and can be reached at