Am2 exam live testing part need some help please!

[RyanF]

Hi everyone,

My resit on my AM2 live testing is monday coming and I need some help/ gudiance on anyone who has sat theres to help me.

Confim polarity by measuring the voltage between each phase to N and each phase to earth, then phase to phase to ensure I am getting 230/400V etc.

So then, Ze test disconnect main earth and test each phase ( 3phases) to earth . Highest value record on test sheet as Ze. Then reinstate the main earth. Make sure test equipment is set to 2 test lead LOW or NO TRIP.

Zs test at db, same as ze but, the main earth is connected. Again test each phase to earth. Record highest value on the test sheet. Again, test meter on 2 test lead Low or No trip.

Then, PFC testing, set the test equipment to 2 test lead high I think it is... then measure PEFC so each phase to earth so L1- E, L2- E and L3-E. Mental note of this value.

Then same test again but PSCC so measuring each phase to neutral. So, L1-N , L2- N, L3-N. Mental note of this value.

The test equipment I am using cant measure phase to phase so. Simply take highest value and double it normally PSCC value.

Record this on test sheet as IpF.

Then cover back on db. Then the board can be fully energised/ lock off taken off. Then carry out RCD tripping times on the ring at the FURTHEST point. Record tripping times on test sheet and functional testing of the test button. Then, functional testing of all other circuits to confirm that they are working as they should be etc.

Then phase rotation ensure I am getting correct phases at the commando outlet point and the motor circuit.

Does that all sound right? If not let me know please as my resit is Monday morning!

Cheers!

 

[polo1]

Ryan, I’ve shown the correct setting on the Megger in my earlier post ( photo). The two lead low test will not trip the rcd on any of the tests you are concerned about. Honest!

 

[RyanF]

But howcome, wont there be no current down the neutral, this causing a imbalance and tripping? Just dont want to do my live tests resit and mess it up.

How would you measure pfc on that tester then?

 

[Jakegood]

I have my am2 next week. Do you know if the sy from DOL to motor is 3 core and earth.
1 Brown, 2 black, 3 grey, then earth not neutral?

 

[sevuk]

Newer Meggers do have a low current, two lead test facility -
View attachment 40813

Yes you are correct, I seem to have completely missed this.

Anyway select the right function using the arrows on the left, with the selection on the right on "Z" and it will also display the PFC. So don't worry.

 

[RyanF]

I have my am2 next week. Do you know if the sy from DOL to motor is 3 core and earth.
1 Brown, 2 black, 3 grey, then earth not neutral?

It was a 1.5mm 4 core SYcable I believe , 3 phases and earth no neutral conductor

 

[RyanF]

Yes you are correct, I seem to have completely missed this.

Anyway select the right function using the arrows on the left, with the selection on the right on "Z" and it will also display the PFC. So don't worry.

So since there is a RCD in the workshop board. But, on the am2 board its a main isolator so I would have to carry out the test on 3 test lead LOW so I dont trip the RCD? When doing Ze, Zs and Pfc tests etc...

 

[sevuk]

There's no guarantee you won't trip the RCD, so far my megger 1741 hasn't tripped any rcds, admittedly I haven't used the 2 Lo function and didn't even know it was there! I've only used the 3 wire test and 2 Hi. I think I haven't seen it because it won't come up as an option if you have all three leads connected, for instance when using the socket adaptor.

It will still display the pfc above the Zs result, as long as you select Z not Z max, no matter what version of the loop test you use. If you can you need the measurement between Line and Neutral for your x2 PFC.

I still haven't finished sorting the electrics in this house so there's no RCDs to test here (talk about the cobblers children having no shoes), I won't be able to give it a go until Monday unfortunately.

Anyone else in a position to give further advice?

 

[Jakegood]

Silly question but when doing a PSCC test you obviously put the dial on the right hand side to L/N not L/LPE.

 

[sevuk]

no option for lo tests on L/N - L/L

you would have to do the two wire test using the green probe and the red probe. Maybe it would trip the rcd if you did L/N as it's supposed to be for L - E...

I want to try it now...

 

[RyanF]

no option for lo tests on L/N - L/L

you would have to do the two wire test using the green probe and the red probe. Maybe it would trip the rcd if you did L/N as it's supposed to be for L - E...

I want to try it now...

Try it and let me know.

 

[RyanF]

no option for lo tests on L/N - L/L

you would have to do the two wire test using the green probe and the red probe. Maybe it would trip the rcd if you did L/N as it's supposed to be for L - E...

I want to try it now...

See he is measure L-PE and L-L/L-N on 3 lead Low test

 

[sevuk]

Mine doesn't do any low tests on LN LL, it's a 1741. There's a lot my tester does that I don't know about, like the inbuilt memory.

If you register for an account with megger and read the manual that might help. Also you can probably find these manuals through dealer websites.

 

[Baker1988]

Hi everyone,

My resit on my AM2 live testing is monday coming and I need some help/ gudiance on anyone who has sat theres to help me.

Confim polarity by measuring the voltage between each phase to N and each phase to earth, then phase to phase to ensure I am getting 230/400V etc.

So then, Ze test disconnect main earth and test each phase ( 3phases) to earth . Highest value record on test sheet as Ze. Then reinstate the main earth. Make sure test equipment is set to 2 test lead LOW or NO TRIP.

Zs test at db, same as ze but, the main earth is connected. Again test each phase to earth. Record highest value on the test sheet. Again, test meter on 2 test lead Low or No trip.

Then, PFC testing, set the test equipment to 2 test lead high I think it is... then measure PEFC so each phase to earth so L1- E, L2- E and L3-E. Mental note of this value.

Then same test again but PSCC so measuring each phase to neutral. So, L1-N , L2- N, L3-N. Mental note of this value.

The test equipment I am using cant measure phase to phase so. Simply take highest value and double it normally PSCC value.

Record this on test sheet as IpF.

Then cover back on db. Then the board can be fully energised/ lock off taken off. Then carry out RCD tripping times on the ring at the FURTHEST point. Record tripping times on test sheet and functional testing of the test button. Then, functional testing of all other circuits to confirm that they are working as they should be etc.

Then phase rotation ensure I am getting correct phases at the commando outlet point and the motor circuit.

Does that all sound right? If not let me know please as my resit is Monday morning!

Cheers!

Highlighted in the red above you say from the Zs/Zdb to get the ipf you go straight to the rcd testing this is not correct as you need to do the circuit Zs on thecircuits you dont have to takeapart to do this (all ones you have to expose live parts on canbe calculated) like the socketcircuit you have to do a Zs ateach socket and then do the rcd test but in the regs it is statedto do it with no load at theclosest socket to the rcd not the furthest.

And as for the 2 lead vs 3 leadon the testers it is totallypersonal preference as the tester can do low current 2 lead and 3 lead testing so its up to you which you choose justmake sure you have set it tolow current and not high current.

 

[Baker1988]

But surely if your testing line to earth of the Ze test wont this still trip the rcd due to the imbalance? So surely you would do a 3 lead test?

As in for pfc what setting would you go on and you can do a 2 lead low test on that as well? But, again wont this trip the rcd?

Some people say do it as a 3 lead test to not trip the rcd and some say do it as a two lead test which wont trip the rcd.

I just need someone to clarify the tests and the setting on the megger tester please!

The whole point in the low current setting is that it will use less current than the 30mA that is required to make the rcd operate so no matter what test you are doing if you set it to low setting it will use about 15mA so wont make any rcd operate. If you test between the PSCC that is between L&N so the rcd won't operate any way as the rcd will only operate on a earth fault not a short circuit.

As for the pfc you test the pefc with either 2 lead on low setting line and earth or 3 lead on low setting standard line, neutral and earth then when you test the pscc you keep it on the exact same setting and if you are useing the 2 lead method you basically move the lead from the earth to the neutral or if useing the 3 lead method you move the earth lead onto the same spot as the neutral either by putting the lead on the neutral lead (as you can normally connect them) or turn the main isolator on and put the earth lead on the neutral bar but you would not be allowed to do this way on the AM2 as you cant turn it of wothout the board cover on so just usr the 2 lead method. Obviously as its 3 phase you would do these tests between all 3 phases.

 

[Jakegood]

Obviously you would take the lead out of earth and put it in nuetral when doing PSCC on 2 lead test. And change the dial on left to L/N?