DC Voltage Fuse Burnt

Either exceeding load limit, or short in the primary switching circuit. Hope it helped Have a nice day

sir, that time load is very less.. 10 to 15 % only.. and after replacing of fuse ups working normally.. so there is no short in the primary switching circuit.. any other resons..

Maybe an intermittent short circuit someplace?

You should exam your loads. More than likely items with large starting currents are overloading your UPS, especially if they are presented simultaneously.

Check the surge current of Your load, specialy if you have a reactive load. Under idel the load current could be fine, the starting reactive load current is usually very high.

When you look at the current, it may help if you use a recorder/data analyser of some sort. Also, look at RMS current, as you may have harmonics due to the type of load being run. Depending on the type of UPS (such as one that usually works in bypass mode and then switch over to battery supply in certain conditions), you could also have some glitch in the transition from normal supply to UPS supply when the primary supply fails.

The only reason a fuse blows is that the current passing through it was more than it could sustain; that is its only job!

Semi-conductor fuse is fast acting to minimise the let-through energy as the semi conductor devices by their size / design cannot absorb much energy.

If you have ruled-out the possibility of any fault in the semi-conductor device or the device, then check whether the enclosure where the fuse is located is hot (not adequately cooled). Higher temperatures can cause premature failure of fuses, if not suitably derated while sizing.

Another possible cause is poor electrical/mechanical connection at one or both ends of the fuse, causing heating of the fuse sufficient to melt the element(s). If this is not the case, the fuse is undersized for the load or an overload occurred; fuses very seldom open spontaneously. Semiconductor fuses are very fast-acting -- in the millisecond range -- and an overload which causes the fuse to "blow" may be of such short duration that the problem is not obvious or, even, apparent.

Semiconductor fuses are usually sized in units of integral I squared dt. Check the ratings of your devices to determine whether your application falls within the operating window. The fuse manufacturer may perform a failure analysis to determine whether the fuse opened under overload, or short circuit conditions. This should get you to the root cause.

If surge /transient current, shorted /leaky component, dirt or over temp were ruled out as had caused the protective device to be activated, then the problem may have been triggered by the premature failure of the semiconductor fuse in itself.... It may have been an aged component probably?

Maybe you need to change out your system for one like the power supplies we have on some of our equipment.

They safely blow the main switching devices to bits before ever ruining a good fuse.

By saying "failure", I think that you mean that the fuse should not be opened because the operational conditions were normal, i.e. the operating UPS current was not exceeding the nominal operating current of the fuse. (Is that right?) If it is so, then maybe it is the inrush current that causes the problem. The inrush current can be really high, especially in the case of capacitive loads. However, if the fuse is located on the input of the UPS circuit there is nothing you can do, except from replacing the fuse and hope that this was just a random incident and it wont happen again. (E.g. maybe the specific fuse part was faulty and, by replacing it, everything will be OK.) But if this problem happens all the time (even after replacing the fuse) then, maybe, there is a design problem and another type of semoconductor fuse should be placed (by the designer of the UPS, not by you) in order to withstand the probable inrush current that may exist.

Semiconductor fuses display aging characteristics. This means that the fault current rating can go down over time. If your fuse was old and operating close to its limit, just replacing it my provide another time constant of protection.

good morning, this semiconductor FUSE installed last 5 years back.. is there any specific life time ?. so that we might avoid this type of failures as a preventive actions we replace the fuse that specifi period.

Hi. I would recomend you do a self test and switch Your system to UPS while montering the rise of current in the process of the UPS taking over the load, that information should give you a solid answer to the problem. Fuses are there to do their job and stop further costly damage. Have a pleasant. Day.

The life of the fuse (for a given operating current) is dependent on the diffusion of metals as they warm up during normal operation. The fuse manufacturer normally supplies this type of information in the form of diffusion/temperature charts. I suggest you contact them. Another tip is that the fuse link temperature is related to the ambient temperature, so I recommend that you determine this prior to contacting the manufacturer.