At present, almost all the power of the led fluorescent lamp is on the market with built-in. A built-in is refers to the power supply can be placed in tubes. This built-in the biggest advantage is that you can make it directly replace the existing fluorescent tube, without having to make any changes to the original circuit. So the shape of the built-in power is usually elongated, in order to plug into a semicircular tubes. There are two kinds of built-in power supply, isolation type (figure 1), a kind of dispute is a kind of isolation type (figure 2).
Unfenced refers to the led load and 220 v input have direct connection, so touching load there is a risk of electric shock. Only between 220 v and aluminum shell aluminum substrate thin insulating layer of isolation, usually not easy through CE and UL certification.
Isolation type refers to the input and output isolation transformer isolation, this transformer may be also may be the high frequency of power frequency. But can be a barrier between the input and output. Can avoid the risk of electric shock. But easily by CE or UL certification.
A, built-in power LED fluorescent lamp of electricity
Using built-in power supply is one of the biggest advantages can directly replace the existing fluorescent lamp without the need to make any changes to the original wiring. This kind of advantage of the built-in is also a cost? Indeed, and the cost is not small. This should speak of from the common fluorescent lamp ballast structure:
We know, the most common fluorescent lamp brightness is to adopt a series of iron core inductor and a parallel electric fluorescent starter (FIG. 3 a). For this kind of circuit when replace directly with the LED fluorescent lamp, just unplug electric fluorescent starter. But because the iron core inductors in series in the circuit, so it is still nearly 6.4 W (Philip) to 10 W (domestic) loss, the results due to this part of the additional loss greatly reduces the LED energy-saving effect. Had a 20 w LED fluorescent lamp, for instance, can replace a 36 w fluorescent lamp, with a built-in unfenced type of 20 w LED fluorescent lamp, for example, the measured results are as follows.
That is, direct replacement as a result of the efficiency is greatly reduced, for domestic inductance ballasts, efficiency is only 56.2%. Only than ordinary fluorescent lamp power saving 6.8 W. This makes the LED fluorescent lamp, energy-saving effectiveness to sell at a discount greatly, so that the contract energy management (EMC) difficult to enforce.
Second, the heat dissipation and lifespan
Another biggest drawback is the life of the built-in power supply is low. Because the power must be put in aluminum tube, aluminum tube can't be made in the form of fins, and can only be ordinary half cylindrical, best plus some shallow bar groove on the surface (figure 4).
This half cylindrical surface area for: 2 h / 2 = PI PI R * R * h. For T8 tubes, its diameter is 26 mm, so the radius of the 13 mm. 1.2 meters of T8 tubes, its surface area is: PI * 1.3 + 120 = 120 cm2, we know that the led radiator surface area usually require 60 W/cm2. , so this kind of aluminum tube heat only scattered around 8 w. Type T8 LED fluorescent lamp input power of 20 w, usually assume that LED the luminous efficiency of only 20%, so there are 16 w input electric power into heat. 8 w heat now only went away, and there are 8 w heat disperse, the result is that the LED junction temperature rising, shorten service life.
Not only that, due to the power supply, built-in power supply heat is added to the tube, assuming the power efficiency of 88%, so there will be 2.4 W heat will disperse, equivalent to a 30% increase in the quantity of heat, that is to say, a total of 10.4 W power can't send out. LED heat dissipation and increase a difficulty, or rather, makes the service life of the LED is more shorter. And the length of the power supply is about one 5 of the length of the tubes, power supply, by the hot focus in this section, also made close to the power of the leds are more hot baking, so life is better than the rest of the LED is shorter, tubes, when damaged, close to the power of a black out first. Can be thought of, built-in power LED fluorescent lamp life will not higher than 10000 hours.
And put the power in the pipe, and the power supply itself must bear very high environmental temperature, produced by the LED street lighting this greatly reduce the service life of the electrolytic capacitors in the power supply, also reduce the service life of the lamps and lanterns.
Three, use cost
Because of the built-in power LED fluorescent lamp life 10000 hours, compared with 50000 hours of external power supply, its use cost apparently high for five times. Not only that, in use process, whether the LED damaged, or power supply was damaged, usually both together to discard. Extra power LED fluorescent lamp, which can then be broken lost which.
In addition, a built-in power source type also adds to the cost of e-waste recycling. Because the electricity supply must be part of the spin-off and processing respectively.
Four, and other functions
External power supply, not only high efficiency, long life, but also can increase the manual dimming or special functions such as automatic adjusting, these are built-in incomparable!
By the introduction of above we can come to the conclusion that built-in shortcomings and problems are serious, it is a pity that some people are only covet it may be 10% cheaper when buy, regardless of its high use cost more than 5 times. Really is a little loss, not worth!
More info you can visit:http://www.lead-lighting.com/products/bid31-1.htm
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