UPS serves as power supply system, inevitable existence comes from the circuitry of many respects to join, include town report to communicate output of input, UPS communication, communication interface to wait. Strictly speaking, these 3 port should install overvoltage to defend.

The overvoltage of UPS defends include double import: On one hand, come from external all sorts of surge or voltage aiguille make certain impact to UPS, need undertakes defending; On the other hand, these surge or voltage aiguille affect load through UPS likely, also need to undertake defending when necessary.

Configure the data center of large UPS or control center, its are in a building or the computer room has more perfect whole to defend thunder system commonly, the overvoltage damage cost that reachs UPS end is not high; And the use environment of small UPS is poorer, besides prevent thunder, the surge impact that considers the operation overvoltage that goes up to circumjacent electrified wire netting even defends.

The choice of the effect of overvoltage preventive measure and cost and its parts of an apparatus and plan is having main concern.

Choose inferior movement voltage and bigger SPD parts of an apparatus that shed a capacity to be able to lower its residual voltage, but behavioral voltage is too low the meeting because of power source not stable cause SPD parts of an apparatus frequent movement and ahead of schedule invalidation, shed the size is larger to cause defend cost is exorbitant.

Normally the circumstance falls, small size UPS still basically is not to consider to prevent thunder, defend to what power source operates overvoltage however.

In inchoate design, stem from cost consideration, small UPS and product of source of other general electrify are similar, it is the zinc oxide that uses 14D471 on 200Vac input EMI is pressed commonly quick resistor (MOV) undertake overvoltage defends.
Origin: Pole of uncut jade of Mian Lai white?
General 14D471 is pressed quick resistor product, its are connected shed a capacity to be in about 6kA (8 ／ 20μs, ) the following, the area that this stabilizes in electrified wire netting does not have a problem, but the area that does not stabilize in electrified wire netting, use 14D471 pressure quick resistor is easier attaint, because operation overvoltage surge and thunder surge photograph are compared,this is, although extent is inferior, but duration is longer, and show periodic, this sheds a capacity to be pressed lesserly to connecting quick for resistor, the quantity of heat that absorbs surge is accumulated continuously and have not enough time to send out, be very easy attaint.

A kind of plan is increase MOV shed a capacity, choose 20D471, 25D471 for example even the MOV parts of an apparatus of 32D471, make connect shed a capacity to raise 10kA to 25kA (8 ／ 20μs, ) the left and right sides. Such, can bear already longer or periodic overvoltage energy have diarrhoea is put, also can make on-line residual voltage maintains in inferior level. Nevertheless, this meeting makes defend cost raises greatly (number increases decuply) .
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