[volt-nuts] Best way to measure micro Ohms

george g_einst at hotmail.com
Mon Sep 18 18:28:24 EDT 2017

The reason that DC is used commercially to measure resistance is simple, if you use AC you may well get the reactive component as well as the resistance coming into play.

Such low resistance measurements commercially are normally only made on high current power distribution networks as part of a periodic test regime where you need to determine the quality/resistance of such things as bus bar joints/connections and loop resistance.

It is not a good idea to use copperslip around aluminium, there is an aluminium based version that should be used, but, be warned, just like copperslip it is an insulator, try putting your meter probes, set for resistance, into a tub of both, I have.  I do not know just why but the aluminium version is just like sand, it gets everywhere when you use it.

To check your joint I would use a four wire Kelvin set up using say 10 Amps from my constant current bench supply and then use my Keithly 616 digital  electrometer to measure the voltage/s present across the joint, a simple application of Ohms law will then give the resistance.

73 George G6HIG

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