20 what is the surge current (Inrush Current)? What are the places that need attention?
Answer: switching power supply power transmission in the input power of the moment will appear a short (1/2~1 power cycle, EX:60Hz power 1/120~1/60 seconds) of high current (according to the product design is about 20~60A, please refer to the product specifications, product) boot after the return to normal current input, each time in the power supply input end transmission moment to appear, this is a normal phenomenon, and will not cause damage to the power supply. But do not suggest continued to power supply startup / shutdown. The other should pay attention to, if the use of a plurality of power supply at the same time when starting, may protect switch will cause the system distribution tripping action, suggest multiple power supply should be spaced one by one to open, or the use of power product function of remote control products on / off.
21 what is the PFC?
Answer: PFC (Power Factor Correction) power factor correction, mainly to improve the power supply input end of the effective power and the ratio of apparent power. Generally do not contain the PFC line model, the input power factor is only 0.4~0.6, and with the active PFC circuit can reach above 0.95, the correlations are as follows:
Apparent power = input voltage x input current (VA)
Effective power = input voltage x input current x power factor (W)
With the environmental protection point of view: the power company power plant must produce more than apparent power, the generator can stable market supply electricity demand, the actual use and power is the effective power. If the power factor is 0.5, said power unit sent to more than 2VA power, can be safe supply of electric power demand of 1W, the energy operation benefit difference. On the contrary, if the power factor is improved to 0.95, generating unit is power company as long as the issue of more than 1.06VA power supply of electric power, 1W needs no problem, the operation efficiency of energy is better.
22 power supply output negative labeled -V or COM difference and why?
Answer: COM (COMMON) refers to the common ground, product labeling according to the attribute of its output is explained as follows:
Single output: positive (+V), negative (-V)
Multi output (total): positive (+V1, +V2...) Negative (COM),
23 Power Supply Catalog in the input end AC input or DC input, difference and why?
Answer: because the power supply product design architectural differences, in the catalog or specification for the input power supply with AC or DC input have the following three categories:
A.85~264VAC; 120~370VDC
B.176~264VAC; 250~370VDC
C.85~132VAC / 176~264VAC by Switch; 250~370VDC
Product specification marked above a, B input power range, whether to send the AC or DC power supply are the normal operation. But the other part model design should pay attention to direct power supply input positive (+) is connected to the AC/L, the negative (-) is connected to the AC/N power supply to boot; part model is connected with a positive electrode AC/N, electrode with AC/L to boot, if the wiring error is no boot, the reverse connection can work normally, and the power supply device there will be other problems.
Product specification marked item C above, the 115/230V must be switch to "230V" position to enter the 250~370VDC, if the switch position in the "115V" into the 250~370VDC will cause the power supply damage, must pay attention to.
24 why product specification marked Input Voltage 88-264Vac, and the machine specification stickers are labeled 100-240V?
Answer: the user sees on the machine labeled input voltage range, in fact, certification, will be the so-called strict + 10% test (IEC60950 +6% -10% and strict), so the voltage range of power supply specifications defined in use is not a problem; and marked on the machine is to meet the safety standard, and to ensure that users can input power correctly.
25 with CE labeled products, whether installed in the other system, can meet the requirements of EMC?
Answer: not necessarily, general power supply device is arranged in the position of the system, group arrangement and grounding system design and so on... Will be affected to a certain extent. Power supply is the same, in different environment or application will often have different results.
26 what is the MTBF? And Life Cycle?
Answer: MTBF and Life Cycle are important pointer product reliability. The so-called MTBF (Mean Time Between Failure) mean time to failure for reliability predictions and expectations, refers to products in the continuous work after a period of time, the average time of the reliability to 36.8%. MTBF is commonly used in MIL-HDBK-217F standard, the parts count method to estimate the expected product reliability value (excluding fan), refers to the product to reach the count at the time of continuous use, can still work normally probability was 36.8% (e-1=0.368). If the product of continuous use counted two times of MTBF time, it can still work normally probability is 13.5% (E-2 =0.135). Life Cycle is a single of the electrolytic capacitor at full load conditions of temperature rise, calculation of the electrolytic capacitor life reference value. For example, the product SP-750-12 MTBF=769.3K hours, Cycle=202.2K hours Life capacitor C108 (Ta=45 C). |
