How to choose and use a switching power supply?

How to choose a switching power supply?
When choosing a switching power supply, the fators should be considered as belows.

1. Select the appropriate output voltage.
2. Select appropriate power. To extend life span of a switching power supply, it is suggested to select one with 30% more than the rated output power.
3. Take load characteristics into cosideration. In case of motors, bulbs or capacitive load, users should select an appropriate switching power supply to prevent overload caused by large current at startup. In case of motors, users should consider backward flow of voltage when the device is halted.
4. Users should consider the working temperature of SMPS power supply and whether the additional auxiliary cooler is needed. Output of the SMPS power supply shall be reduced in higher temperature conditions.
5. Choose the features of SMPS power supply according to demands
   Protective features: overvoltage protection, over temperature protection, and over load protection etc.
   Application features: signal functions (indication of normal and failure status), remote control, remote measuring, and parallel connection etc.
6. Comply with the applicable safety certification and EMC certification.

How to use a switching power supply properly?
Here are some tips for using a switching power supply properly for your reference.

1. Confirm whether specifications of input or output voltage comply with nominal value of the power supply before use.
2. Check whether input and output leads are correctly connected before powering on for prevention of equipment damages.
3. Check whether various components are tightened up. Check whether there are contacts between screws and electrical parts of power panel. Measure insulation resistance between shell and input or output leads for prevention of electric shock.
4. Make sure the ground terminal is properly connected to the ground to grantee safety and reduce noise waves.
5. Multiplexed output refers to a power supply with primary and secondary output. The primary output performs better than secondary output. In general conditions, the one with larger current is the primary output. To ensure adjustment rate and dynamic indicators of output load, it is required to at least carry 10% of its load. If using secondary output instead of the primary one, users should exert dummy load on the primary output. Please refer to the specifications of different models for more details.
6. Please note that the frequent switching of power supply will have negative influence on its life span.
7. Operating environment and on-load level will influence life span of switching power supply.