Confusion with prospective fault current test

[DNS1]

Hi guys,

Been getting a bit of practice with my new Metrel MI3000.

Most functions are fine, but I'm a little confused by the Z Loop impedance test.

In the book, it shows the Line, Neutral and PE probes being connected to their respective terminals on the board.

When I do this and press test, the machine reboots and gets confused.

However, when I connected the Neutral and PE probes together on the earthing terminal all was fine and I got a realistic reading.

Anyone know what I'm doing wrong/right?!

 

[DNS1]

Oh, it's TN-C-S

 

[Deleted member 26818]

I would guess, that there is a high resistance joint on the Neutral, or you are not making good contact with your probes/clips.

 

[DNS1]

To add more confusion, I've looked up a symbol that was being displayed briefly before the machine seemed to restart and it's says it's a warning that phase voltage has been detected on the PE terminal.

Totally bewildered by this one! All the other tests were pretty self-explanatory!

 

[trev]

Are you confusing PFC and PSCC? Don't know about your Metrel but on mine it's two different functions

 

[DNS1]

Mine has 2 different functions too, but the leads are supposed to be connected the same way according to the diagrams.

Brown to incoming line, blue to incoming neutral and green to earthing terminal.

 

[trev]

On mine, brown blue and green is the same as yours for PFC, but for PSCC you combine the blue and green leads

 

[DNS1]

I've just done the test again and found that the test works properly, as long as I don't touch the "Test" button for too long! (if I press it the button but keep my finger touching it, it complains). If I press and remove my finger straight away, it works fine.

The manual mentions how the Test button is also a PE touching electrode. Anyone know why?! This would appear to be why I'm having trouble!

Is it there to detect if I'm getting shocked and discontinue the test?

Excuse the stupid questions!

 

[Richard Burns]

If you are slightly charged with static and the test button is used as a PE reference you have a potential and the meter thinks there is voltage on the Earth and stops the test. If you press the button with an insulated screwdriver it will read correctly.
I keep meaning to stick a bit of sellotape over half the test button so if I have problems I can pres the covered half, but never got around to it.

 

[DNS1]

Ah, that explains why the manual mentions about standing on a non-insulating surface.

I was on a plastic chair, on carpet and wearing trainers, so I guess I'd probably be statically charged.

Was trying to find out what the specs were for charge detected on the button, but the manual doesn't say.

 

[CrazyScozzese]

I use my sleeve on mine.