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Applications & Solutions : Does It Make Sense to Use a PLC for Lighting Control?

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Does It Make Sense to Use a PLC for Lighting Control?

Which is better for lighting control – a PLC or dedicated lighting control? Find out what makes the most economic sense in light industrial applications:

With today’s advances in technology, should a Programmable Logic Controller (PLC) assume the role of a building automation and lighting control system? 
From driverless cars to smart buildings, automation is revolutionizing every aspect of our lives. On the floor of manufacturing plants, a collaborative robot, or CoBot, works alongside a person on an assembly line. The CoBot takes on the heavy lifting, repetitive tasks, and errand running so the human can work faster and more efficiently. Underneath a nearby control panel, a Programmable Logic Controller (PLC) orchestrates the various directions and speeds of equipment while the building automation and lighting control systems monitor and manage ventilation, humidity, temperature, and lighting. 
Advances in industrial automation may make you wonder why PLCs don’t overtake the role of a building automation and lighting control system? To answer this, let’s start with a little history on PLCs and lighting control systems. 

Programmable Logic Controller (PLC) 

The PLC was invented in 1968 when General Motors sought an electronic replacement for hard-wired relays and timers that could accurately and reliably control the repetitive starts and stops of machinery. These hard-wired systems required the very time-consuming and expensive task of manually rewiring thousands of relays each year. The introduction of the PLC, and the evolution of relay logic, enabled automated control in the harshest environments while reducing the size and complexity of large relay panels. 
They are still relied on in automotive manufacturing, as well as in food processing, material handling, pharmaceuticals, and many other industries. PLCs have evolved to accommodate the very sophisticated control strategies manufacturing machines now require; hence very sophisticated software solutions are required within the PLC. A PLC can be programmed via multiple programming languages familiar to software engineers. This level of sophistication makes PLC systems inherently expensive; furthermore, one incorrectly programmed PLC can cause plant downtime or create a dangerous condition. 

Lighting Control Systems 

Lighting Control Systems evolved out of light controllers and have always been about turning on and turning off the lights. This singleness of purpose has led to controllers that are highly evolved. They are widely used on both indoor and outdoor lighting of commercial, industrial, and residential spaces to maximize energy efficiency, improve occupant comfort, satisfy building codes, or comply with green building goals. 
Having been born in the building control environment, lighting control systems have an easy time interfacing with other building systems and benefit from the familiarity that installers, designers, and users have with these and similar systems. They can be accessed remotely through a computer or smart device. This empowers building managers with a complete, holistic view into the building’s operational status, energy consumption, and utilization. 
They are capable of sophisticated control scenarios that adapt to environmental and human factors in real time, such as dimming and granular management by cubical, section, floors, or entire building. This level of sophisticated control has led to systems that can be easily commissioned on startup and easily modified over time. 

Which is better for lighting control – a PLC or dedicated lighting controls? 

Manufacturers need to control things that move in various directions, at various speeds, and under tightly controlled torque levels. Building control, specifically lighting control, require management of a load. The precision needed for placing an Oreo® cookie in a package versus dimming a light circuit is like comparing your home’s systems to the International Space Station. 

The go-to controller for heavy industrial applications can effortlessly handle the automated control requirements of a modern building, however, some might argue that the costs of a PLC – equipment, design, implementation – outweigh the benefits. 

Conversely, a lighting controller can be a low-cost PLC substitute in light industrial applications. In less sophisticated panels, the scheduling functionality and programming capabilities that some digital DIN rail lighting controllers offer are extremely powerful. 

PLC programming tools are complex and require significant specialized training in order to develop code for a PLC. In contrast, lighting controllers are only slightly more complicated than programming your alarm clock. They also offer the convenience of Bluetooth wireless connectivity and iOS and Android Apps for easy programming or to speed up multiple installations. 

Typically the amount of memory and processing power required for manufacturing exceeds that needed for lighting control. As a result, the circuitry inside a lighting controller is less expensive. 

Lighting control systems frequently have integrated relays that can support the lighting load. Typical PLC systems require external relays. Both systems may still require contactors for larger loads. Since relays are needed in both systems, the economic advantage is reduced. However, the component count and relay selection tasks are both reduced with lighting control systems, saving designers and installers valuable time. 

In the end, a PLC can be used as a lighting control system. However, it does not make economic sense when you consider the increased hardware, the programming complexity, and installation time of PLC systems over lighting control systems. Explore the features, benefits, and specifications of Grässlin by Intermatic digital DIN rail time switches for a cost-effective and time-saving solution.

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