UK High PSCC and strange readings - help much appreciated

[CalB4676]

So went back to the house today for the remedials, borrowed a megger LT300 loop tester from a friend of mine who works at the hydro who happened to be in the area. his tester was giving a value of 0.13/0.12 so calculating it out you have a pfc of about 2kA. Tried his leads in my mft and was getting readings about 0.18ohms/1.29kA L-E, 0.11ohms/2.54kA L-N. So looks like it’s either tester or leads. Got a new pack coming tomorrow I’ll give it a go on my own supply and see. If not perfect excuse to get the megger x1

 

[CalB4676]

The trnasformer for the house was also about 80mtr up the road from the house. So value read was about the ball park he expected.

 

[nicebutdim]

Leads are basically consumable items and don't tend to be made to a particularly high standard.

 

[Teddy Lop]

Good shout on the test leads.

I'd assumed the OP is (hopefully) doing a "2 - Hi" high current test. There isn't a "3 - Hi" and I don't think he should confuse matters with low current tests that are inherently flawed anyway.

(One of my dislikes about the Meggers 17 series is that the significant differences between lo and hi tests is under-emphasised by the user interface. Earlier models has a No Trip setting on the mode dial, suggesting (correctly) it's a completely different test method.)

Another thing well worth having. I've long held the view that any self respecting sparks collector of junk should keep an old tester or two for muddy farmyards, fault finding, and exactly this scenario to give a 2nd opinion. It needn't be expensive or professionally calibrated if you have your own check box.

Yes the megger 17xx defaulting to low current every time is annoying. Low current is good for nowt more than making observations IMO.

Also while on test leads, my Megger was acting up on continuity tests on multiple lead sets, a gentle tap with the pliers on the inserted test lead plug stops it - the "end" of the socket on the machine seems to need a connection and not so much the side? Time to pop it open I guess.

 

[Marvo]

Glad you got to the bottom of it. You'll probably find a nice new set of silicone test leads sorts it out, if not maybe send it in for calibration and see if they can fix it. Sometimes the female socket that the leads plug into breaks the solder joint that connects it to the circuit board its mounted on. I've managed to repair testers where this has happened in the past just by resoldering the socket sleeve onto the PCB. Obviously you've got to open up the tester to do this and it will need to go for a new calibration test afterwards.

 

[timhoward]

Yes the megger 17xx defaulting to low current every time is annoying. Low current is good for nowt more than making observations IMO.

100% agree.

Also while on test leads, my Megger was acting up on continuity tests on multiple lead sets, a gentle tap with the pliers on the inserted test lead plug stops it - the "end" of the socket on the machine seems to need a connection and not so much the side? Time to pop it open I guess.

This may help

Issues with megger mft1720 - in - Electrical Tools and Products

, Issues with megger mft1720, Electrical Tools and Products, ElectriciansForums.net Est.2006 | Free Electrical Advice Forum and page_number.

www.electriciansforums.net

 

[Teddy Lop]

100% agree.

This may help

Issues with megger mft1720 - in - Electrical Tools and Products

, Issues with megger mft1720, Electrical Tools and Products, ElectriciansForums.net Est.2006 | Free Electrical Advice Forum and page_number.

www.electriciansforums.net

FFS - popped it apart, found the same issue and thought I'd update...

You guys were already there!