transformer

[09387078]

Transformers since the phases and neutral all connect together in the windings ,then when you set a meter on ring/ohm it should ring out when you go phase to phase or phase to ground/neutral right? Transformer is a 480 primary:208/120 secondary.

 

[augie47]

I can't recall if the resistance was low enough to "ring" and that may depend on the tester, but on the secondary and primary side you would definitely show a low resistance between all leads, but no resistance between any primary and secondary lead.

 

[zog]

No idea what "ring out" means. Are you asking how to test a LV transformer?

To accurately measure winding resistance you need a winding resistance test set to charge the windings, otherwise your ohm readings with a ohmeter are pretty much worthless. Phase to phase values should be the same.

Phase to gound with the nuetral disconnected(if wye) and other side (Pirmary or seconday depending on which side you are testing) needs to be grounded and a megometer used to measure insulation resistance. IR reading taken at 30 sec, 60 sec, and 10 minutes and DAR/PI ratios calculated.

TTR ratios should also be measured and compared to nameplate values.

 

[cadpoint]

Come on Salty

No idea what "ring out" means.

Can I say that maybe you've forgot where you came from as to where You've been ?

I think more than a few in the crowd would understand, Ringing it out, I'll give you the accounting on the method!

OK, I'm recalling Dad saying, did you ring it out...

 

[SG-1]

Ring-out is a method of continuity testing that requires a battery, bell, & some leads. My bell with 2 D cells will ring up to one ohm. If placed across a transformer secondary winding it vibrates & you do not want to come into contact with the primary windings, they will eat you up ! Voice of experience speaking...

Soares makes a reference to "ring-out" in the last paragraph on page 27 of the 10th edition.

This method is alive and well where I work. It came to us from the East Pittsburgh Works of Westinghouse Electric.

 

[zog]

I meant in reference to testing a transformer, never heard of someone ringing out a transfrormer.

 

[wiigelec]

Transformers since the phases and neutral all connect together in the windings ,then when you set a meter on ring/ohm it should ring out when you go phase to phase or phase to ground/neutral right?

It depends on how many leads and the winding configuration of the transformer. More information would help answer your question.

Do you suspect an open winding in either the primary or secondary of this transformer?

 

[kwired]

I meant in reference to testing a transformer, never heard of someone ringing out a transfrormer.

Depends on what you are testing for. I test doorbell transformers for open circuit all the time with simple continuity testers. If open circuit test fails on a transformer like this there is no point in doing any other testing it needs replaced.

 

[09387078]

soory wrong word used

soory wrong word used

Depends on what you are testing for. I test doorbell transformers for open circuit all the time with simple continuity testers. If open circuit test fails on a transformer like this there is no point in doing any other testing it needs replaced.

Sorry what I meant to say was continuity on a fluke meter. When you get continuity on a fluke while set on ohms it will ring and that was what I meant .let me explain my problem. we are installing the service and everything else that go after in a 250k sq ft building .we had to set 3 208/120 transformers for general purpose like offices after the 480 service , my boss comes in and puts the fluke on the secondary side of the trans and it shows continuity between phase to phase /phase to ground. I tell him it?s because the winding are connected and that?s why he is getting continuity( there?s no service voltage yet if wondering)then he puts the meter to the panel the secondary is connected to , and says there?s a short so I open the ocd and show him the panel phases are not grounded and that he was getting back feed through the winding .well I was not going to argue with him and he even started making me second guess myself .so here I am asking you guys question that I already know .so if you understand where I?m coming from set it in stone for me.

 

[kwired]

Sorry what I meant to say was continuity on a fluke meter. When you get continuity on a fluke while set on ohms it will ring and that was what I meant .let me explain my problem. we are installing the service and everything else that go after in a 250k sq ft building .we had to set 3 208/120 transformers for general purpose like offices after the 480 service , my boss comes in and puts the fluke on the secondary side of the trans and it shows continuity between phase to phase /phase to ground. I tell him it?s because the winding are connected and that?s why he is getting continuity( there?s no service voltage yet if wondering)then he puts the meter to the panel the secondary is connected to , and says there?s a short so I open the ocd and show him the panel phases are not grounded and that he was getting back feed through the winding .well I was not going to argue with him and he even started making me second guess myself .so here I am asking you guys question that I already know .so if you understand where I?m coming from set it in stone for me.

You are right. Transformer secondary will have continuity between all terminals as they are all connected together through the transformer windings. If you do not have continuity you have an open circuit in the transformer somewhere. Your boss is wrong on this one. There should not be any continuity between the primary and secondary of the transformer - with no external connections made up anyway.

 

[wiigelec]

If you want to check for a ground in your feeder conductors you can disconnect your main bonding jumper and isolate the "neutral" connection on your transformer from ground, in which case you shouldn't get continuity to ground...