Ze Tns system

[Duane B]

Well it looks like it was maybe the cable joints, lots of holes in street, complete power down, new joints pots going in in a few places with the look of it, can't do much more till that lots put back in. Lol what a problem I've caused, 

 

[Duane B]

Why would it only be for dead testing? Do you not understand why leads are nulled (zeroed)?

nulling of leads is a useful facility whereby you can measure and store the resistance of the test leads in the meter so that the result displayed is actually the measured resistance minus the resistance of the leads. In years gone by you would have measured the resistance of the test leads, and then measured the resistance under test (including the tests leads) and then calculated the actual resistance under test by deducting the resistance of the test leads from the test measurement. 

Obviously the modern electrician is incapable of such simple mathematics so the meter does it for us.

So any measurement of resistance where the resistance of the test leads could alter the results requires some sort of nulling of the leads.

Was educated years ago to deduct leads from final readings, I do understand why we do it,  just getting my head around the fluke, does the leads hold the zero in memory for duration of the testing or is it a re zero every test, new test with these flukes, as some say once done it's done ??????

 

[Phil Pallent]

When live testing the meter uses up to  a maximum of 200mA, and acquires the Ze reading from the voltage present between Line and CPC. No need, let alone a way of nulling.

 

[kerching]

When live testing the meter uses up to  a maximum of 200mA, and acquires the Ze reading from the voltage present between Line and CPC. No need, let alone a way of nulling.

Best have a word with Fluke then...unless their manual,is wrong....

just reading the instructions

 

[Sharpend]

Oops that'll be the way to do it then!

 

[kerching]

Dont know if it applies to other makes.....but i dont actually give a **** as i do not use other makes

just reading the Courgetting manual

 

[Phil Pallent]

Fluke always remember test probe leads resistance even when the machine is switched off. It means you only null out once, unless you either change the leads or your batteries go flat; then the result is stored in the machines EPROM.

 

[Sharpend]

Well I'm fairly sure that's not quite correct, I find that if I null at the beginning of the day then the null will be ok for the day, although this is only whilst machine remains on, if it is turned off then for how it takes I null everytime. 

 

[Rob_the_rich]

its fine if Fluke remembers what the last zero was, but do you remember what leads you last used? I have the plug lead which zeros at about 0.26 and the separate leads which zero at about 0.14

So I often zero before testing

 

[Blue Duck]

Always zero prior to testing too, temperature also changes things a wee bit.

Just forming habits.

 

[Davethsparky]

When live testing the meter uses up to  a maximum of 200mA, and acquires the Ze reading from the voltage present between Line and CPC. No need, let alone a way of nulling.

I hope it's applying more than a piddling 200mA to attain a live test result 

 

[SLIPSHOD & SLAPDASH]

Have Fluke improved this since the earlier model where you had to zero the leads when switching between loop and continuity  ?

 

[apprentice87]

When live testing the meter uses up to  a maximum of 200mA, and acquires the Ze reading from the voltage present between Line and CPC. No need, let alone a way of nulling.

I hope it's applying more than a piddling 200mA to attain a live test result 

Err, depends..

If i choose a "high" current loop test, my Megger 1730 will draw 4 amps. If i choose the low current "no trip" option, it is obviously going to draw somewhat less then 30mA.

john..