Voltage Rating on High Voltage Fuses

[richanton]

Is there a problem with using a higher voltage power fuse in a power distribution system. For instance, if I have a choice between a 5.5kv fuse and a 14.4kv fuse for a 4800 volt system, does it matter if one or the other is installed.

 

[kevin1shah]

Is there a problem with using a higher voltage power fuse in a power distribution system. For instance, if I have a choice between a 5.5kv fuse and a 14.4kv fuse for a 4800 volt system, does it matter if one or the other is installed

No dear friend ther is no problem with using a higher voltage power fuse in a power distribution system. the only disadvantage is cost is high. we can not use lower voltage rating fuse in apower distribution system.

 

[cuky2000]

Fuses works base on the melting principle of the heat generated by the Joule effect I^2R.

Fuse could perform OK for lower voltage within a range typically determine by type test. (see enclose sample for range voltage of 17 to 38 kV )

http://www.bussmann.com/library/docs/BoricAcidCat.pdf

Fuse rated for higher voltage are more expensive including the rest of the associated instalation.

SUGGESTION: Consult the fuse manufacturer technical data before specify fuse for a particular application.

 

[dpc]

If you are using current-limiting fuses (CLF), you cannot necessarily use any higher voltage fuse. CLFs produce high transient voltages during interruption.

Generally, the voltage rating of your CLF should not exceed 1.41 times your nominal system voltage. Of course, it has to be at least as high as your voltage. So you have to stay within that range.

The over-voltage concern does not apply to expulsion fuses or low voltage fuses, as far as I know.

 

[jbartos]

Suggestion: Generally, the higher voltage levels have smaller short circuit fault levels, therefore, the smaller current interrupting ratings/capability are specified. The lower voltage levels have larger current fault levels, therefore, the higher rated current interrupting rating/capability of protective device is required. Therefore, it is necessary to verify if your higher voltage level fuse has the sufficient current interrupting rating/capability. The voltage requirements are covered by the above postings.

 

[Bung]

dpc is right about the CLFs (aka HRC fuses). They use the build up of voltage in the arc to help blow out the fault, and the rate of voltage buildup is determined by the internal geometry of the fuse and the voltage rating. Too high a voltage rating means too a dv/dt, and some resulting transient overvoltages.

Bung

 

[cuky2000]

All low voltage fuses will function on any lower voltage, but use on higher voltage than rated is hazardous.

Medium voltage and high voltage fuses made of solid material boric acid power fuses are not voltage critical in that they can be applied at voltages less than their rated voltage with not detrimental effect.

Current limiting fuse are modernly designed with peak-voltage generation control are mainly a function of system voltage and are not voltage critical (See S&C Cat 212-30 pag 5).

However, other current limiting fuses designed base in the pulling action of the electromotive force, are mainly function of the rated voltage are more voltage critical. It is recommended to consult the manufacturer specification and application guide.

Current limiting fuses are use well bellow their rated voltage in several applications, but normal practice is to avoid using them at less than about 70% and up to 100% of rated voltage.

For fuse operated at lower voltage than the rated voltage the arc-voltage generated should be compare with the connected upstream including the surge arrester and BIL of the equipment.

Fortunately, this phenomenon is not an issue for system voltage bellows 8 kV and many installations above this voltage most installation have sufficient dielectric capacity to withstand the arc voltage.

REFERENCES:
1- IEEE Std 242
2- S & C Descriptive Bulleting 212-30 for (34.5 to 138 kV Fuses)
3- GE Application Manual GET-3039G
4- Elect Dist System Prot- Cooper Pwr. Systems[/color blue]

_{PS: Please relay my best regards to all amigos in B&R including Al.}

 

[stevenal]

http://www.sandc.com/pdfs/200/212_30.pdf

Expulsion fuses like the SMD referenced above are not voltage critical. Might want to choose a different reference for current limiting fuses.

 

[redtrumpet]

Good point, stevenal. S & C is quite critical of current-limiting fuses in their literature as I recall.

 

[cuky2000]

Dear Stevenal,

I should clarify that there are CLF more voltage critical than others depending of the type of fuse design such as ribbon vs. straight cartridge/spring link.

The fuse manufacturer state:
"SMD fuses are not voltage critical and therefore may be applied at any system voltage equal or less than the rated voltage of the fuse. Moreover, these fuses operate without producing overvoltages that can cause spurious operation of surge arrester or contribute to failure of transformer insulation"

There are other fuses such as S&C CLF cutout (Fault Tammer 450-30,32) rated for 25 kV are not recommended to be used in 15 kV system because there is concern that the 15 kV surge arrester protecting the transformer could operate.

The suggestion that I would like to present is that the engineer responsible of this selection should have an independent opinion verifying in all cases that the arc-voltage is within the limit of the dielectric capability of the upstream equipment.

 

[jbartos]

Suggestion. There are also physical dimension aspects to be noticed. Visit

http://www.yangyangindustry.com/fuse-2.htm

for fuses that fit certain voltage ranges only.

 

[richanton]

Well, my question really sparked some interest. Thanks for the replies.

To summarize, it appears you should just buy a fuse with the exact voltage rating if that rating is available. Otherwise, buy the next higher standard rating. This will not get you into trouble whether you are using current limiting or expulsion fuses.