Milli-ohm evaluation of HRC Fuses with HIOKI RM3542A resistance meter

[Kiriakos GR]

HRC fuses made for Multimeter they do considered as special due their speed and amount of current that they can interrupt.

Inspection method of HRC fuse when this is loaded over a multimeter, this is beautifully described at most User Guide of most multimeter in the market.
FLUKE corporation this is famous at supplying this information in their documentation.

Especially FLUKE corporation they do mention specific resistance test limits for its product model, when measured resistance difference this is major, the fuse should be replaced even if it not burned.
HRC fuse production issue or absorption of humidity, both are good reasons so one fuse to be replaced.   

It is expected Internal resistance of HRC fuses to not be identical but simply inside tolerance limits.
Manufacturers of HRC Fuses does not offer documentation of resistance tolerance.

I own HRC Fuses of most manufactures, some HRC fuses was sends to me by FLUKE corporation,  I have SIBA Fuses from my Agilent multimeter, and also fresh batch from Ebay 440mA which this is what I am burning accidentally when testing DC power supply.
I do not sacrifice quality standards and I am an Bussmann customer. 

HIOKI RM3542A this is treasure especially for milliohm measurements, and I thought to record internal resistance differences among HRC fuses mostly of Bussmann between old and new production fuses and even an comparison with SIBA fuses.

My stock this is:
11A  qty of three HRC (Bussmann distributed by FLUKE)
11A SIBA qty 1

440mA qty of four HRC,  new Bussmann for eBay ( shipped from ASIA).
440mA qty one HRC (Bussmann distributed by FLUKE)
440mA qty one HRC SIBA Fuse

Test results :
HIOKI RM3542A measuring range 100 milliohm

11A  qty of three HRC (Bussmann distributed by FLUKE)
a) 7.649 milliohm 
b) 7.552
c) 7.839

11A SIBA ( 9.873 milliohm  )

HIOKI RM3542A measuring range 1000 milliohm

440mA qty of four HRC,  new Bussmann for eBay ( shipped from ASIA).
a) 739.650 milliohm 
b) 756.360
c) 729.700
d) 735.100

440mA qty one HRC (Bussmann distributed by FLUKE)
667.700 milliohm 

440mA qty one HRC SIBA Fuse
1075.923  milliohm 

While I have perform over 500 high precision measurements this year, by using HIOKI Kelvin clip harness  and also with Kelvin clip harness which I made for increased compatibility between meters using BNC or Banana inputs,  HRC fuses are quit larger in diameter and I did use four cables and large alligators. 

One conclusion can be formed by 100% certainty after my own measurements, and this is that characterization limits of bad or good HRC fuses these are not a difference of few milliohm or of few tenths of milliohm.

Handheld multimeter in general they have 600 ohm lowest measuring range, and few exceptions go down to 30 Ohm, these meters will never measure milliohm. 
But these meters they are fully capable to measure resistance value of their fuses.


Last day ITTSB Blog home page this is updated with interesting projects for lovers of ultra high precision resistors.
Have a look     www.ittsb.eu