An:You should consider the following aspects:

1. To increase the reliability of the Switching Power Supply, we suggest you should choose a unit that has a rating of 30% more power than actual need. For example, if the system needs a 100W, we suggest that you should choose a Switching Power Supply with 130W of output power or more. By doing this, you can effectively boost the reliability of the Switching Power Supply in your system.
2. We also need to consider about work ambient temperature of the Switching Power Supply and whether there is additional device for dissipating the heat. If the Switching Power Supply is working in a high temperature environment, we need to make some derating to the output power. The derating curve of “ambient temperature” versus “output power” can be found on our spec sheets.
3. Choosing functions based on your application:
1. Protection function: Over Voltage Protection (OVP), Over Temperature Protection (OVP), Over Load Protection (OLP), and etc.
2. Application function: Signaling Function (Power Good, Power Fail), Remote Control, Remote Sensing, Parallel function, other Special function and etc.
3. Making sure that the model qualifies for the safety standards and EMC regulations you need.

2.When the load is motor, lamp or capacitive load, why the power supply can not start successfully?
An: when the load is motor, lamp or capacitive load, the starting current is so high that it can cause OCP(over-current-protection) of power supply, then the power supply can not start successfully. It is suggested that sampling the current to realize over-current-protection function when design a power supply.

3.Why power supply shut down in use, and work again after re-start the power supply?
An:Generally speaking, there about 2 reason cause the shut down of power supply, first is over load in short time and cause OLP(over load protection), so it is suggested improving the output power of power supply or modify the design of OLP circuit. Second is the high rise of temperature, and cause OTP(OVER-TEMPERATURE-PROTECTION). The both reason explaining above can cause power supply shut down for protection, after the removal of abnormal condition, re-start the power supply will make it return to normal .

4.what is inrush current? When need to notice this phenomenon?
An: when the SMPS are switched on, they load the supply network momentarily(1/2~1 period, EX:60Hz line 1/120~1/60sec.) with high current pulses(according to practice product about 20~60A , refered to the SMPS spec.), this is called inrush current. inrush current must be limited, SMPS come from different company has different of the inrush current limited method base on the use of different concepts., so after the SMPS switched on, the input current become normal, the inrush current diminished. this is a normal phenomenon, but we suggest that do not switched SMPS on and off repeatly, in addition, when many SMPS are switched on at one time, the MCBs and breaker have to be designed to prevent nuisance trips or contact welding, so we suggest that the SMPS switched on one by one with some period, or To employ the product with remote control function such as remote on/off.

5. How to choose the electronic ballast?
AN: You should consider the following aspects:
1) High reliability. Although the product reliability does not have any standard to stipulate, but is really the product most important performance. The product reliability comes from the product design, the product manufacturing entire process, and the consummation quality control method. The product reliability reflects in failure rate of using initial period.
2) Must have the good starting ability, the good preheating start will lengthen the lamp life.
3) Low harmonic. The standard has " L " and " H " two limit ranks. " L " is the low harmonic,   " H " is the high harmonic. " L " may use in every situation, but " H " can not use in the big area or use in the high-quality place.
4) Has the abnormal state protection function. When the lamp has each abnormal state, the electronic ballast ought to be able to withstand or start the automatic protection, avoids damaging
5) Small electromagnetic interference. Electronic ballast’s interference is mainly the conduction way. The conducted interference will affect other electric equipment’s normal work.
6) High efficiency. In the electronic ballast supplies lamp essential power guaranteed that achieves the stipulation brightness under the condition, the electronic ballast's power is smaller, the efficiency is higher.