Autonomous dimming of LED lights

Replacing outdated light sources with modern ones is the right step towards economical use of funds for lighting and obtaining high-quality lighting. Street lamps based on sodium lamp (arc, sodium, tubular), which until recently had no alternative, give way to a street lamp of a new type – LED (Light Emitting Diode). Replacing street lighting based on sodium lamp with LED you save energy up to 50%, not to mention the savings on the work of replacing broken lamps – LED lamps work 5 times longer than sodium lamps. But LED lamps provide another great opportunity to cut down your energy costs – dimming. Dimming is reducing the lighting level of the luminaire at a time when we do not need too bright light. Indeed, why make the lamp work at full power in the dead of night, when there is no one walking on the street? Having reduced the brightness, we not only decrease power consumption, we also increase the life of the lamp in 1.5 – 2 times! And this is also a significant savings, both on the cost of the lamp itself, and on the works on its replacement.

So it turns out that you need a device that will control the work of the lamps – to reduce and increase the brightness when necessary. In order to do that, smart lighting control systems based on dimmable street lights and street lighting controllers were invented.

They allow you to control the light, turning on and turning off the lamp, transfer it to night mode with reduced power consumption, transmit data on the status of each lamp, etc., using PLC (Power Line Communication) technology or wireless data transmission over the radio channel, collect statistics on the lamp and report in case of external situations. But here, as in any other technical system, there are modules that do the main, the so-called “useful work”, and there are modules that provide the system with certain additional functionality that usually requires significant expenses. But is it always necessary? For example, for an investor who performs modernization of street lighting in the city as part of an energy service contract does not make sense to “overpay” two or three prices for additional service functions – the project’s attractiveness is reduced considerably. And what about small enterprises, institutions or urban settlements, in which the number of lamps illuminating the surrounding area or street is 10-100? They will never buy a control system for their external illumination.

For such cases, there is a solution based on a stand-alone street lighting controller. This device does all the work that brings income – switches lights at night to the low-power mode according to the scheme of 100%-50%-100% or 100%-75%-50%-75%-100% of the rated power. The 380/220 V line of street lighting can be turned on and off by any automatic equipment, including the one already installed in lighting control cabinets, from a photo relay to advanced centralized control systems on GPRS modems.

The result is a street lighting control system with the so-called “distributed intelligence”, which is way more reliable than the centralized one.

A similar approach is used now, for example, in the hi-end class fire alarm systems, where the sensor, and not the fire alarm station, detects the presence of fire in place.

This electronic device (hereinafter referred to as a dimmer), housed in a compact, encapsulated housing with wired connectors. Dimmer has dimensions of 45mm x 30mm x 15mm. For setting on the front panel there is a dip switch. If you need to obtain an IP67 enclosure protection grade, after adjusting the dimmer, you must apply a transparent protective neutral silicone sealant over the dip switches.

The dimmer is based on a fairly powerful “self-learning” microcontroller that daily fixes the lights turn-on — turn off time and calculates the so-called “estimated midnight”, from which the start and end time of the dimming is set (see Fig. 1 and 2). So, to program a dimmer, you need to find out the time for switching on and off the lighting and determine the middle of this interval. This will be the “estimated midnight”. And this figure is true for any month of the year +/- 10 min! Now that we know the time of the “estimated midnight”, all we need to do is set up dimmers with the help of special DIP switches, the time for lowering the power to this “estimated midnight” and after it.This is called a dimming plan. You do not need a complex and not always reliable methods and systems for transmitting control commands over the power network or radio channel from the controller to the control cabinet and from the control cabinet to the lamps! Knowing the actual operating time of the lighting system for the last three days, the dimmer itself will ensure timely switching of the luminaire to the night power down mode and back. So the dimmer functions completely autonomously! At the same time, the dimmer ignores long and short switching intervals that may occur during repair of lighting lines or malfunction of the control cabinet.

In the simplest case, you can set a dimming plan in three steps: in the evening, the brightness is 100%, in the night – 50%, in the morning 100%. Or set a more flexible five-step schedule: 100% – 75% – 50% – 75% – 100%.

In the five-step mode, the dimmer can save up to 40% of electricity.

In addition to the function of time-based power reduction, dimmer has the ability to work with motion sensors. When a 220V signal is applied to this input, the dimmer switches the luminaire from low power mode to full power mode.

This option can be used, for example, when lighting pedestrian crossings, inner areas of industrial enterprises, warehouse complexes and in other areas where personnel or vehicles rarely appear at night.

Dimmers are installed in each outdoor lighting fixture. This can be done at the factory where lamps with dimmable drivers are produced or directly on the object during the reconstruction or replacement of the lighting system. No external connections of the luminaires between themselves and with the lighting control cabinet are required. The only condition: the luminaire power supply must be dimmable using the 0-10V protocol.

When you install a dimmer on a 100W power LED lamp, it will pay off by saving on electricity within 1.5-2 years. The strengths of this solution are low price, ease of installation and configuration, reliability.

The use of an autonomous dimmer gives the opportunity for a minimal price to flexibly control the light and thereby obtain savings by reducing electricity costs and extending life of LED luminaires. The result of energy savings is a reduction in CO₂ emissions into the environment. This question is very relevant for the modern world because of its influence on the state of the environment. Companies that do care about CO₂ emission and global warming problem will, without a doubt, acquire a positive image from both the public and the state.

A standalone dimmer is an excellent and inexpensive solution for creating intelligent lighting systems for small objects such as parking near shopping centers and hypermarkets, secondary streets or objects where installing an expensive full-fledged control system with remote control is impractical.