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New industry Technology regarding to Bussmann fuse, ABB breakers, Amphenol connectors, HPS transformers, etc. 

From a medium voltage fuse accident

Time:2021-09-09   Author:ABPower   Browse:

Recently, in an industrial part of Chepo district, Guangzhou City, China. It happened 1-hour power off. This caused the China Southern Power Grid paid great compensation to the electricity user due to very huge economic loss in this area.

When the accident found, service engineer goes to the scene immediately to change the ABB  transformer.

Then start to find the rootcause.

ABB transformer 1.png        ABB transformer.png

Engineer find that there is 1 pole had been damaged seriously.

So called fuse supplier- Cooper Xian fusegear  to check together.


Cooper Xian fusegear chief engineer Mr. Wu comes in 8 hours. After check the damage status, the transformer capacity, the fuse ratings, the damage time, the transformer download datasheet etc. information, comes out the analyses report:

1, The medium voltage fuse customer using (PN: SFLDJ-12KV/100A) is not genuine Cooper Xian fusegear. How to tell?

1), From the company name




False Medium Voltage fuse 

Genuine Medium Voltage fuse

False medium voltage fuse logo.pngGenuine medium voltage fuse logo.png


2), From the medium voltage fuse touching cover


Cooper Xian fusegear genuine medium voltage fuse use 99.99% silver for the touching covers, Base on the physical characteristics of silver, it’s very easily oxidized in air. So, the surface is kind of matte.

Tips: Cooper Xian fusegear is an acquired fuse manufacturer of Eaton Bussmann in Year 2012.Silver is the best choice for electrical connecting in fuse industry.

Cooper Xian all medium voltage fuse use 99.99% in fuse conductor including touching cover to keep the perfect performance.


But This medium voltage fuse surface looks very shiny. Normally this is bright tin platted over the raw material, since the silver is very expensive, the supplier wants to reduce the cost, so they can use the alloy then plate tin. It looks good, but the connecting performance is not stable.


 False medium voltage fuse cover.png      Genuine medium voltage fuse cover.png

2, From technology

Customer does not select the right medium voltage fuse for this transformer.


Checking Cooper Xian medium voltage fuse application guide,

If the fuse rating is over 100amp, engineer should reduce at least 15% rated capacity(current) for fuse in closed transformer inside.

Base on IEC standard, medium voltage fuse is working stable in tempeture of -25C to 40C. when working tempeture is higher than 40C, each 1C raised, engineer should consider to reduce 1% on the fuse current.

For example: when it’s 45C working environment, if previously use fuse rating is 100amp, then it’s 100/ (1-15%-5%) =125amp fuse current should be used.


The installation environment is significant factor for medium voltage fuse selection.


Back to this ABB transformer, the transformer capacity is 100KVA, so in normal situation, the 15% loss should be considered, and due to the closed transformer environment, at least 5~10% tempeture higher should be used.

 medium voltage fuse application guide to transformer.png

So, the fuse they should use is: SKLDJ-12KV/125A or higher.

But customer choose SDLDJ-12KV/100A. which is not suitable.


This fuse is no more than $100 per piece, but the electricity grid compensates more than $300,000 to user. It should be a unforgettable experience.



1, Pls choose Cooper xian fuse distributor to buy the genuine fuse;

2, Pls contact us or Bussmann if you do not know how to select a proper fuse.




SKLDJ-12KV/125A, Bussmann medium voltage fuse cross reference Part No.: 12TKLEJ125

SDLDJ-12KV/100A, Bussmann medium voltage fuse cross reference Part No.: 12THLEJ100

New industry Technology regarding to Bussmann fuse, ABB breakers, Amphenol connectors, HPS transformers, etc. 

TAG:  cooper xian fusegear