Silicon-controlled dimmer is just as bad as incandescent light and leaded gasoline

Lighting consumes nearly 20% of the global electricity every year. Compared to developed countries, lighting energy consumption of developing countries accounts for a higher proportion. Incandescent lights are cheap, but their efficiency is very low. If they are fully replaced by energy saving bulbs or solid state lighting, hundreds of power plants are unnecessary, and each year more than ten million tons of carbon dioxide emissions can be reduced. Now EU has already planned to gradually phase out incandescent lights from 2009 to 2016; United States is also expected to gradually prohibit the use of most incandescent lamps from 2010 to 2014. Although Japan has not passed a similar legislative measures, a leading lighting brand, Toshiba, already fully shut down their incandescent production line in March 2010, ending its 120-year history of manufacturing light bulbs. On the other hand, China is actively building its large-scale LED lighting industry. China, India and Japan banning incandescent lamps will also happen within a few years.

Competition between the two horses: energy saving light bulbs and LED lighting

Once incandescent lamps are phased out, the average home and commercial lighting will present a situation of two heroes competition between energy saving CFL bulbs and LED lighting. LED lighting has surpassed energy saving light bulbs in many functions, therefore, it is considered as the preferred lighting option for 21st century. The advantages of LED lighting include:

1. LED does not contain toxic materials, but the energy saving bulbs have a certain content of mercury.
2. Different from the energy saving bulbs, LED does not emit ultraviolet rays.
3. LED lighting efficiency is equal to energy saving bulbs, but its efficiency has continued to increase, while the prices become cheaper and cheaper.
4. The lifetime of LED light bulbs is as several times as energy saving bulbs. Japan’s Panasonic announced that their LED light bulbs have a lifetime of 19 years.
5. Under the environment of -40 degree Celsius, LED bulbs can still be functioning, but for most energy saving bulbs, it is difficult to start or operate when the temperature is below 10 degree Celsius.

Many industry analysts predict that LED bulbs will fully replace the energy saving light bulbs in 2015. This view is based on the conclusions of competetion between LED and CCFL products at other markets in recent years. They noted that LED backlight has pushed CCFL backlight to the edge of being phased out in applications of cell phones, tablet PCs, notebook computers, so the market experts are confident to predict that LED backlight will replace CCFL backlight in the application of LCD TV and LCD screen. According to this, LED lighting surpassing CFL lighting in five years is a reasonable prediction.

Potential destroyer

Many engineers and companies’ breakthrough achievements in LED lighting technology bring us this lighting revolution, we shall applaud to thank them. However, we are worried that the potential destroyer, silicon-controlled dimmer, will erode, even overthrow the most benefits that LED lighting revolution brought to us.

We know that dimmable lighting can further improve energy saving effects. But among the main three types of dimming LED lighting, the silicon-controlled dimmer seems like a hideous monster, devouring the results we obtained from developing dimmable lighting with our hard working.

Dark side of Silicon-Controlled Dimmer

Dimming mode of silicon-controlled dimmers is cut off part of the Sinusoidal AC current waveform which is provided to bulbs. Thus, silicon-controlled dimming light bulbs have a low power factor which is always lower than 0.5. But please be noted that the power factor is an important indicator about power efficiency and power quality. Perfect power factor is 1.0. Only in phase sine current with harmonic distortion of zero can achieve the power factor of 1.0. In recent years, on the harmonic distortion of current waveforms of many electrical and electronic equipments, EN / IEC 61000-3-2 standards have very strict specifications. In the past, most computer power supplies have a power factor of 0.5 to 0.7. Now EN 61000-3-2 and other government regulations, such as Energy Star of the United States Department of Energy, required that the electrical equipments such as televisions, computers and so on shall reach at least a power factor of 0.9.

Moreover, silicon-controlled dimming LED bulbs shall add some capacitor snubber circuits to avoid light bulb flickering when dimming. But doing so will make the low power factor become even lower, which is often less than 0.10. Meanwhile, the current waveform of power supply line will become a series of surge current. Harmonic distortion of current waveform will be far more than specified limits. According to the author’s over thirty-year experience on electronics industry, no other products can cause such a serious damage to power factor and current waveform like silicon-controlled dimmer.

Figure 1 shows current waveforms of silicon-controlled dimmer when dimming at different dimming positions. We can clearly see the low power factors and severe current surges at different dimming positions.

Figure 1 current waveforms of silicon-controlled dimmer at different dimming positions

Bleeder Resistor

In addition, silicon-controlled dimmer seems to be an energy saving device, actually it is not. Although the silicon-controlled dimmers can reduce power consumption of incandescent lights, it does not mean that these dimmers can also save power when used for silicon-controlled dimming LED bulbs. This is because when dimming, LED light bulb is a small load to the traditional silicon-controlled dimmer. But the load is too small, which will make the silicon-controlled switch devices unstable, leading to serious LED bulb flickering. We all know to fix this flickering problem, we need to add dummy load or bleeder resistor into silicon-controlled LED light bulb. But usually in dimming state, the bleeder resistor must consume 1W to 2W to effectively overcome the flickering problem.

This approach of adopting bleeder resistor revealed the dark side of silicon-controlled dimming LED bulbs, that is, low efficiency and excessive standby power. Please be noted that the Energy Star program in the near future will improve the efficacy of solid-state lighting to 56lm/w. Obviously, the silicon-controlled dimming LED bulbs can not meet the requirements of continuing to improve lighting efficacy. In addition, Energy Star has specified the standby power consumption of most electronic equipments, including telephone, television, computer and so on. Nowadays, standby power consumption of personal computer and television is already less than 1W. The Energy Star’s next goal is to decrease standby power consumption of many small electrical appliances  to 0.3W or less. The total electricity consumption of lighting is much more than other small electrical appliances, specifications to its standby power consumption would be more important.

In addition, the Energy Star program has zero power consumption requirements for solid-state lighting when it is turned off. When dimming deeply, the state of silicon-controlled dimming light shall be  the same as turned-off or standby mode. But in fact, the bleeder resistor wastes more than 1W of power.

Silicon-controlled dimming LED bulbs can not meet Energy Star specifications, whether power factor, lamp efficiency, or turned-off mode power consumption.

As mentioned above, silicon-controlled dimmer has several fundamental flaws which can not be effectively solved. Silicon-controlled dimmer is a monsterall who most seriously violates energy saving and power quality among all electronic equipment. Therefore, the use of silicon-controlled dimming LED bulbs will only help spread its evil consequences to the electricity grid throughout the country.

The nightmare could be like this: a major city installed silicon controlled dimmers to all its commercial and residential lighting. Around midnight, the majority of office buildings, factories, and the families will set the dimmable lighting to deep dark mode. No one notice that these lamps at 120Hz frequency will form surge current simutaneously. Serious current harmonic distortion caused noise, interfering communications network, television, radio, computer and household appliances. Some systems fail, and can not be used. Meanwhile, the current surge has also spread to turbogenerators in the power plants. Generators start to vibrate. Power plants must switch off the turbogenerators before the vibration can not be controlled.

The damage that silicon-controlled dimmer causes to power factor, and the extent that it damages the quality of power supply and wastes standby power is unparalleled.

Silicon-controlled dimmer is a product that is invented in last century. Even if it has already existed for half a century, its natural flaw of destroying power factor can still not be solved. Just like contemporary leaded gasoline, or add a little mercury to the fluorescent lamps, silicon-controlled dimmer gives people an illusion of quickly overcoming the problem. But decades have passed, we must pay a heavy price to our ignorance. Unfortunately, some companies may not understand, there are some other companies ignoring the defects of silicon-controlled dimmers, continuing developing LED lighting products which match with silicon-controlled dimmers.

We call upon the power companies, government regulators, environmental groups and technology organizations can deeply understand the dark side of silicon-controlled dimming lights. We suggest that silicon-controlled dimmers and lamps should be regulated by Energy Star specifications, when in dimming mode, the power factor, efficiency and standby mode power consumption and other aspects shall meet the requirements of various specifications. If it can not meet specification requirements? We hope that competent authorities shall declare early that silicon-controlled dimmer are not applicable for energy-saving lighting applications.

Note: In fact, any electrical or electronic experts can tell you the silicon-controlled dimmer’s inborn defects that they destroy power factor and current wave is unsolvable.

Options to replace silicon-controlled dimmer

So what can replace the silicon-controlled dimmer? Now there are two main alternatives, one is remote control dimmer, the other is the EZ dimming.

Remote control dimmer use infrared or radio waves to transmit control signals, similar to television or air conditioner’s remote control. Their main drawback is high cost. Installing infrared or radio receivers on the ceiling or inside the lamps costs much more than the general non-dimmable lamps. Another drawback that must be overcome is that different brands of remote controls must be compatible. Unfortunately, once involving the development of a common industry standards, the manufacturers all consider their own interests as priority, and it is difficult to achieve consensus.

EZ dimming is a new generation of dimming technology invented by New Green Technology. EZ dimming is the solution with the lowest costs. It integrates all dimming control functions in a dimmable LED driver. And EZ dimming lights can use the original wall switch, no need re-wiring, and no additional hardware facilities are required.

In fact, the normal operation of EZ dimming LED lamp is the same as non-dimmable lights. Switching on the wall switch will brighten all lights, and switching off the wall switch will dim all lights, turn off the switch on the full dark.

If you want to dim the lights in corridors, toilets, office rooms, parking lot at night, or late at night dim the lights in public buildings such as hospitals, schools, train stations and so on, switch the wall switch once (the action from fast turning off to fast turning on), you can dim the light to 60% brightness. The second switch can dim the light to 40% brightness, the third switch can dim the light to 20% brightness, the again switch will dim the light to full brightness.

To directly jump from any dimming position to full brightness, you just let the wall switch stay at turned-off mode for more than 1.5 seconds, then switch on the wall switch, all lights will be dimmed to full brightness. To directly jump from any dimming position to full darkness, just switch the wall switch into off mode.

Figure 2 shows current waveforms of EZ dimming light bulbs at different dimming positions. AC current waveforms are all smooth curves without surge. whichever dimming position it is at, the power factor maintains higher than 0.9.

Figure 2 current waveforms of EZ dimming light bulbs at different dimming positions

Figure 3 operation method of EZ dimming light bulbs

Zero-cost dimming program

In fact for most occasions, we only need to add a simple dimming function to general lighting. That is say the public buildings such as offices, shops, schools, hospitals and so on, usually only fully turn on or turn off; only at night, work, or out of business, you can dim the light of some areas. Four-grade dimming of EZ dimming already can meet this basic demand of dimming. Situational lighting and other areas which need stepless dimming, manufacturers can develop their own remote control dimming or other dimming programs, but must meet the specifications of power factor, efficiency, and standby power consumption.