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Why smps will be shut down and can restartafter shutting down?
Ans:
1.To expand service life of the power supply, we suggest you choose the one with 30% more output power. For example, if you need a power supply with 100w, you should choose the one with more than 130w output power. And in this way the service life of power supply can be effectively improved.
2.Working environment and extra assistant radiating facility have effect on the power supply. If the power supply working in a situation with high temperature, it will decrease the output power.
3.Choosing function as you required. 1. Defensive function: OVP, OTP, OLP.   2. Application function: semiotic function (Power Good, Power fail), remote function, telemetering function, Parallel function and etc.  3. Special function: PEC and UPS
4.Choose the correct UL and EMC.

Why smps will be shut down and can restartafter shutting down?

Ans:
There are two reasons for the power supply down. First overload causes overload protection, increasing the output power or modifying the overload design is the solution. Second, temperature is too high and OTP function works. If power supply down with these two reasons, solve the problem and start up. 



What’s inrush current and what should pay attentionto?


Ans:
1. Switching power supply at the instant of the input power transmission will be a brief heavy current (1/2 ~ 1 power cycle, EX: 60 hz power supply 1/120 ~ 1/60 of a second) which is about 20 ~ 60 A according to the product design. Please refer to the product specification. Product boot will be back to normal after the current input, each appears at the instant of sending power, which is a normal phenomenon and will not damage the power supply. But switching on/off more than one power supply continuously is not recommended. Also, it should be paid attention to, if you use more than one power supply at the same time, please turn on the power supply one by one or use the remote function to turn on, for it may cause power distribution systems to protect.

4. What is PFC?

Ans:
1. The main function of the PFC (Power Factor Correction) factors is to improve the Power supply input ratio between effective Power and apparent Power. Generally the PFC circuit model is not included for its input power factor is 0.4 ~ 0.6, while active PFC circuit can reach more than 0.95. Here are the relevant formulas: Apparent power =Effective power = input voltage *input current *power factors By the view of environmental protection, electric power company must produce power which is greater than the apparent power of electricity, so the generator can meet the electricity supply market demand. And the actual use of electrical energy is the effective power. If the power factor is 0.5, which means the power generating set must produce more than 2 VA power to meet the demand of the electric power 1 W. In a word, the energy efficiency is poor. But on the other hand, if the improving power factor is 0.95, the power company generating set should provide as long as 1.06 VA power to supply power 1, which means energy efficiency is better.


What’s thedifferences between information class(EN60950-1)and medical class(EN60601-1)?

Ans:
According to safety standard, EN60950-1 Class I,the max leakage current less than 3.5mA, while EN60601-1 less than 0.3mA.Meanwhile, safety distance and the quantity of fuse have differences, fordetails as following form listed:


What’s MTBF? What’s the difference between MTBF and life cycle?

Ans:
MTBF and Life Cycle are important to the product reliability. MTBF (Mean Time Between Failure) refers to the time that the products cost when their reliability getting to 36.8% after continuous work for a period of time. Ming weft MTBF adopts the MIL - HDBK - 217 F standards currently which adopts parts counting method to estimate the product reliability expectations (excluding fan), refers to that the product can still work normally and the probability is 36.8% after continuously using and reaching the counting time, (e - 1 = 0.368). If the products use almost twice as long as the counting MTBF, it can still work normally and the probability reaches 13.5% (e - 2 = 0.135). The Life Cycle of the product refers to the electrolytic capacitor Life reference value calculated on the condition that the electrolytic capacitor is in full load and temperature is rising. Such as product SP - 750-12 MTBF = 769,300 hours, capacitance C108 Life Cycle = 202,200 hours (Ta = 45 ° C).