LED fluorescent lamp built-in flaws and security risks

CREE LED lamp is used with AOD super bright white LED as light source, the shell is acrylic / aluminum alloy (customer-defined). Housing available PC pipe production, high temperature of 135 degrees. LED panel light with the traditional fluorescent lamp in the dimensions are the same caliber, length 60cm and 120cm, 150cm three, the power was 10W, 16W and 20W, and 20W traditional fluorescent lamp (ballast) the actual power consumption of about 53W , 40W traditional fluorescent lamp (ballast) the actual power consumption of about 68W.
     Currently, almost all led fluorescent lamp on the market are based on built-in power supply. Refers to the so-called built-in power supply can be placed inside the tube. The biggest advantage of this built-in is that you can make a direct replacement for existing fluorescent tubes without having to make any changes to the original circuit. Therefore, the shape of the built-in power strip usually do grow in order to go into the semi-circular tubes. There are two built-in power, a non-isolated (Figure 1), one is isolated (Figure 2).

Non-Isolated refers led 220V input terminal and the load has a direct connection, so there is risk of electric shock load touch. 220V only between the aluminum plate and aluminum thin insulating layer of isolation is usually not easy to pass CE and UL certification.



      Isolated refers to the input and output isolation transformer isolation transformer may be the frequency that may be high frequency. However, both the input and output isolated. Avoid the risk of electric shock. It is easy to pass CE or UL certification.



First, the built-in power LED lamp power consumption

With built-in power The biggest advantage is that you can directly replace existing fluorescent lamps without the need to make any changes to the existing wiring. So this kind of built-in advantage is not also pay a certain price it? Indeed, and this consideration is not small. This should be talking about ordinary fluorescent lamp ballast structure:


We know that the most common is the use of a fluorescent lamp starter of a series inductor and a shunt core of the starter (Figure 3a). For this circuit with a direct replacement LED panel light.  just unplug the starter on it. However, due to iron-core inductor in series with the circuit still, so it still brings nearly 6.4W (Philip) to 10W (domestic) loss, the results of this part of the additional losses due to greatly reduce the LED power-saving effect. For example, originally a 20W LED lamp can replace a 36W fluorescent lamp, with built-in non-isolated 20W LED fluorescent lamp, for example, the measured results are as follows.



In other words, the result is a direct replacement for efficiency is greatly reduced, for domestic magnetic ballast efficiency of only 56.2%. Only saving than normal fluorescent lamp 6.8W.
This makes the power-saving LED lamp performance greatly reduced, resulting in energy management contract (EMC) is difficult to enforce.

    Two, heat and life

Another built-in power biggest drawback is the low life. Because the power supply must be placed in the tubes, so that the fin can not be made in the form of tubes, but only an ordinary semi-cylindrical, at most, on the surface of the strip with some very shallow grooves (Figure 4) .




This semi-cylindrical surface area: 2πR * h / 2 = πR * h. For the T8 lamp, it has a diameter of 26mm, so the radius of 13mm. T8 lamp 1.2 m, a surface area of: π * 1.3 +120 = 490cm2, we know that the surface area of ​​heat sink LED generally requires 60cm2 / W. Therefore, only the semi-tubes of the heat dispersion 8W. The T8 LED fluorescent lamp type is usually the input power is 20W, LED luminous efficiency is assumed that only 20%, then there are 16W of input power into heat. And now only disperse heat 8W, 8W calories while still trapped, the result is to make the LED junction temperature rise, shortened life expectancy.

Moreover, the power supply built, the power of the heat also added to the tube, assuming 88% efficiency power supply, so there should be dispersed 2.4W calories, equivalent to 30 percent while increasing the heat, that is a total of There 10.4W power can not be distributed out. Makes the LED heat added to a difficult, or that makes the LED's life is also more shortened. Moreover, the power supply for the lamp length of about one-fifth of the length, the power supply is issued in this period of heat is concentrated there, so close to the power of these baking hotter by the LED, and thus the life of the LED is more than elsewhere short, the lamp if damaged, close to the power of a first black out. Can be considered, built-in power LED lamp life of not more than 10,000 hours.

And put the tube inside the power, the power generated by the LED itself, but also to withstand the high ambient temperature, which greatly reduces the power in the life of electrolytic capacitors, it reduces the lamp life.


Third, the cost

Because built-in power LED panel light life of only 10,000 hours and 50,000 hours compared to the external power supply, the use of cost apparently five times higher. Moreover, in the course, whether it is damage to the LED, or power supply is damaged, usually two to be discarded. The external power LED lamp, which can be a bad throw which.

In addition, the built-in power supply has also increased recycling of electronic waste disposal costs. Because the power section must be ripped out and then treated separately.

Fourth, other functions

External power supply, not only high efficiency, long life, but also can increase the manual or automatic dimming dimming and other special features, which are built-in unmatched!

From the above we can conclude that the introduction of built-in disadvantages and problems are very serious, unfortunately, some people just covet it may be cheaper to buy 10%, regardless of its use of high cost five times more. Turns out to be big for the small loss, more harm than good!

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