A1:LED has many advantages, such as no toxic substances, environmental protection, long service life, high photoelectric efficiency, etc. The design, production and manufacturing process of LED chips has been quite mature, and the damage of the whole LED lighting system is mainly the damage of LED drivers; Low-quality LED driving power supply directly causes LED chip damage due to imperfect protection, low constant current accuracy and large current fluctuation. Therefore, LED driving power supply is the key of LED lamps and lanterns, which is just like a person's heart. To manufacture high-quality LED lamps and lanterns for lighting, high-quality LED power driver must be selected to meet the requirements of poor working environment and high maintenance cost of LED lighting system.

A2:

1) Design and manufacture of non-professional power supply companies (the requirements are too scattered and the quantity is too small);
2) Not designed according to the harsh working environment of LED lamps:
  A)-40 to 70 degrees ambient temperature
  B) Inadequate waterproofing design
  C) Lightning protection design is not in place

A3:1) Standardized professional design process control Technical pre-research, feasibility assessment, preliminary design, detailed design, engineering prototype, small batch trial production. 2) Reasonable design margin of components 3) Selection of high quality components Electrolytic capacitors, IC, power semiconductors, magnetic components, etc. 4) Strict quality verification and testing procedures Stress analysis, EVT, SVT, DVT tests, MTBF calculation and experimental verification.

A4:High efficiency is the energy-saving requirement of LED lighting system as a whole, and it is the foundation and guarantee of low temperature rise, long life and high reliability. 1) High efficiency, low loss and low temperature rise For example, an output 100W LED driving power supply, when the efficiency reaches 95%, its loss is 5.2 W, when the efficiency is only 85%, its loss is 17.6 W, the latter is 3.4 times of the former. Experiments show that the temperature of the former is 10 ~ 15 ℃ lower than that of the latter under the same conditions. 2) Reduce the working temperature of LED lamp and delay light decay The increase of LED chip temperature will lead to the change of LED performance and the attenuation of electro-optic conversion efficiency, and even fail in severe cases. Experimental tests show that the luminous flux will decrease by 3% every 5 degrees Celsius when LED temperature rises. 3) High efficiency, low temperature rise, long life If you choose 105 degrees, High temperature electrolytic capacitor with a life of 10,000 hours, According to the prevailing electrolytic capacitor life estimation company, "every 10 degrees reduction doubles the life", Then its working life is 20,000 hours in 95-degree environment and 40,000 hours in 85-degree environment. For example, when the working temperature of Infineon drive power supply is generally 70 degrees, the temperature of electrolytic capacitor is roughly controlled at about 85 degrees, and the working life can reach 40,000 hours. If it works for 12 hours every day, the working life is nearly ten years. 4) High efficiency, low temperature rise and high reliability With the decrease of power supply temperature and the improvement of working environment of IC and power semiconductor, MTBF (Mean Time Between Failures) will increase significantly.

A5:PF is the abbreviation of Power Factor, which refers to the power factor and the ratio of active power to apparent power; PFC is the abbreviation of Power Factor Corrector, which refers to power factor correction; High power factor can: 1) Reducing current harmonics; 2) Increasing power system capacity; 3) Reduce line loss and save electric energy. Low power factor means low power efficiency, and the lower the power factor, the higher the proportion of power consumed in the distribution network. If the low power factor is not corrected, the power company will provide more reactive power besides active power, which leads to the need for larger generators, transformers, transmission lines, etc. to compensate for the loss. Power supply with PFC function can improve its own energy utilization rate, reduce losses, and also reduce harmonic pollution to the power grid.

A6:MTBF (Mean Time Between Failures) is an important index to measure the reliability of products. The value of MTBF can only be counted correctly after a certain number of products have been used for a certain time. It refers to the average time from the product leaving the factory (life start) to the failure (life end), which is two different concepts from the actual life value of a single product. In fact, it is impossible to count the MTBF value of a product after it is put into use, so the reliability prediction of the product should be carried out in the design stage, and it can also be verified by subsequent experiments. At present, the most common authoritative standards for MTBF calculation are Bellcore and MIL-HDBK-217, which are used for civilian products and military products respectively. Among them, Bellcore is proposed by AT&T Bell Laboratory and becomes the industry standard for MTBF calculation of commercial electronic products, while MIL-HDBK-217 is proposed by Reliability Analysis Center of US Department of Defense and Rome Laboratory and becomes the industry standard, which is specially used for MTBF calculation of military products. Lifetime refers to the life of the power supply. For most power supplies, including LED drivers, the component with the shortest life will be electrolytic capacitors. The life calculation is the reference value calculated according to the temperature rise of the electrolytic capacitor under a certain load condition and the life formula given by the capacitor manufacturer.

A7:Glue filling of LED driving power supply is beneficial to heat conduction and waterproof: 1) Through glue filling, the heat of the element can be led out and released through the shell, so that the internal temperature is uniform and the overall temperature is reduced. 2) The interior of the power supply is filled with glue, and through the cooperation with the shell and other structural parts, the infiltration of water molecules is reduced, and the waterproof performance is improved, thus improving the outdoor adaptability of the LED driving power supply.

A8:

Surge (lightning protection) test standard is IEC6100-4-5, and the grades are as follows:

Level (级别)	Open-circuit test voltage ±10 % kV
1	0,5
2	1,0
3	2,0
4	4,0
X	Special（特殊）
NOTE： X can be any level,  above, below or in between the other levels. This level can be specified in  the product standard.

There are four criteria for judging test results:
1) There is no electrical influence;
2) Occasionally, the electricity works intermittently, but it can automatically reply;
3) Stop work, and restart after power failure can recover;
4) Damage.

A9:

Constant power supply mainly means that the output current of the power supply can be adjusted, and the output voltage of the power supply can automatically adjust the adaptable output range according to the set output current, so as to ensure that the output power of the power supply is constant.
Taking our EBD-150S105DVA as an example, for example, through software setting, the power supply can be used as a 150W power supply with output current of 700mA and output voltage range of 97-214V, or as a power supply with output current of 1000mA and output voltage range of 97-150V.
Constant power supply can effectively reduce the types of customers' power products, reduce procurement costs, facilitate batch stocking and shorten the delivery time of power supply.

A10:You can't. When connected in parallel or in series, the power supply may not work properly.

A11:

When LED lamp manufacturers choose LED power supply, they find that the power of the whole LED lamp is less than the rated value in the initial state of lighting, and the power output of the whole LED lamp gradually reaches the rated value after the LED lamp heats up. The reason is that the series voltage of LED lamp beads is greater than the rated output voltage of the power supply, and the power supply is in the limited power protection mode.
The positive Vf value of each LED bulb is typically 3V in normal heat engine and 3.2 V in cold engine, which may be higher at low temperature. Therefore, when matching LED power supply, the appropriate power supply model should be selected according to the highest Vf value of the actual LED cold state.

A12:The safety shell temperature of a product refers to the maximum working shell temperature at the designated position allowed by the safety regulations when the product is certified by the safety regulations, regardless of the long-term life of the product. Warranty shell temperature refers to the maximum working shell temperature of power supply limited to ensure that products can work stably and reliably during the warranty period.

A13:In order to prolong the life of POWER SUPPLY, it is recommended to choose more than 30% rated output power. For example, if the system needs a 100W power supply, it is recommended to select a model with an output power rating greater than 130W, and so on, which can effectively improve the life of POWER SUPPLY.
In addition, it is necessary to consider the working environment temperature of POWER SUPPLY and whether there is additional auxiliary heat dissipation equipment. In the excessively high ambient temperature, POWER SUPPLY needs to reduce its output. Please refer to the product specification for the derating curve of annular temperature versus output power.
Select each function according to the application requirements:
Protection functions: over-voltage protection (OVP), over-temperature protection (OTP), over-load protection (OLP) and so on
Special functions: work factor correction (PFC), uninterrupted power supply (UPS).

A14:Generally, there are two reasons for the power supply to crash in use. First, it may be overload protection caused by instantaneous overload of load. It is recommended to improve the output power of power supply or modify the overload design; The second is that the temperature rise is too high, and the phenomenon of temperature protection occurs. All the above situations will cause the power supply to crash due to entering the protection state, and the power supply can return to normal after the state is lifted.

A15:The switching power supply will have a short (1/2 ~ 1 power supply cycle) at the moment when the input power supply is sent, EX: 60Hz power supply 1/120 ~ 1/60 seconds) of large current (about 20 ~ 100A according to product design, please refer to product specifications), the normal current input will resume after the product is started, and it will only appear at the moment of power transmission at the power input terminal every time, which is a normal phenomenon and will not cause damage to the power supply. However, it is not recommended to continuously turn on/off the power supply. In addition, it should be noted that if multiple power supplies are used to start up at the same time, it may cause the protection switch of system distribution to trip off. It is recommended that multiple power supplies should be turned on one by one at intervals for product on/off.

A16:

PFC (Power Factor Correction) power factor correction is mainly to improve the ratio of effective power to apparent power at AC input of power supply. Generally, the input power factor of models without PFC circuit is only 0.4 ~ 0.6, while that with active PFC circuit can reach more than 0.9. The correlation formula is as follows: apparent power = input voltage x input current (VA) effective power = input voltage x input current x power factor (W)
From the viewpoint of environmental protection, the power plant of the power company must generate more than the apparent power, so that its generator set can stably supply the market demand for power, and the actual use of power is the effective power. If the power factor is 0.5, it means that the generator set can safely supply 1W of electric energy only when it generates more than 2VA of electric power, and its energy operation benefit is poor. On the contrary, if the power factor is improved to 0.95, as long as the generator set of the power company generates more than 1.06 VA, the demand for supplying 1W of electric energy will be no problem, and the operation benefit of energy will be better.
Active PFC can be divided into single-stage PFC and two-stage PFC according to line architecture. Please refer to the following table for comparison.

A17:

When the output current of the power supply exceeds the rated current, the protection circuit acts to reduce or cut off the output power.
Overcurrent characteristics are divided into the following types:
Protection mode:
(1) FOLDBACK CURRENT LIMITING
The output current capacity will decrease under overload, generally to below 20% of rated current, as shown in curve a in the figure.
(2) CONSTANT CURRENT LIMITING
When overloaded, the current remains within the defined range, while the output voltage will drop, as shown in curve b in the figure.
(3) OVER POWER LIMITING
The higher the current under overload, the lower the voltage proportionally, as shown in curve c in the figure.
(4) HICCUP CURRENT LIMITING
When overloaded, the voltage and current drop rapidly and cut off the output, but it will automatically return.
(5) SHUT OFF
When overloaded, the output will be cut off, and the output voltage and output current will approach zero.
Reply method:
(1) After the overcurrent (overload) state is lifted, Auto Recovery.
(2) After the overcurrent (overload) state is released, restart (Re-Power-On).
Precautions: Avoid prolonged overload or short circuit, which may shorten or damage the power supply. The overload or short circuit protection of some models is designed in a compound mode, and its protection mode is as follows: first set current limit (or Foldback Current Limiting or Over Power Limiting) and then turn off (or Hiccup Current Limiting) after a certain period of time.

A18:Please confirm whether it is IP67 product with ADJ adjustment function and IP67 product with ADJ adjustment function. Because the product adds issues related to adjustment hole and waterproof plug structure, the weather resistance of the product is worse than that of general IP67 product (without adjustment hole). It is recommended to choose products above IP67 grade without adjustment hole for direct outdoor application.

A19:

North America: UL8750, UL875  Display screen products: Europe, Middle East and Africa
Molded case waterproof power supply/U-shaped light box power supply/ordinary waterproof power supply/adapter: CE EN 55032, EN 62368, EN 61000-3-2 required
Europe: EN 62368, EN 55032 CB: BS EN55032-1, BS EN62368-1
North America: UL EN 62368-1
India: BIS