HELP IDENTIFYING TA 1/3000 TRANSFORMERS - Page 1
Forum section: electronics / repair

author: alitronix
author_rank: Contributor
timestamp: June 12, 2023, 10:02:59 pm
content: Hello ,first of all ... I don't know if here is the right place to put this questions ... maybe is more OK in the beginners section.... I'm not very familiar whit this forum... BUT ....I'm wondering if someone here can help me, of course there are many people here who I'm sure is recognized this "component" immediately.I'm experienced in low voltage and in digital section not in power... so I'm not very familiar whit "power components" ... even if I can recognize them.So... I came across with this TA things in attempting to help a friend of mine , to repair a sort of industrial motor controller for him.So on the board I found two of this transformers ... from the circuit I deduce they are read the current from a motor and is read the current flow by a MCU, because thru a OPTO they go thereand thru the "1 wire coil" pass high voltage.Please don't judge me, all of us have gaps in knowledge , I always say to me ... I always think in every morning that I don't get out of bed if I don't learn something that day.So be patient.How they are called? What they exactly are?Where can I find to buy one of this ? ... because during my tests/plays/measurements/voltage injection... I fried out one of those, well is happening...how can I search for him? even a wiki link is good for methe "primary coil" is measuring around 780 Ohm and 8H inductancethanks for an eventually response/help .excuse me but English is not my native languages.here some pics :

author: srb1954
author_rank: Super Contributor
timestamp: June 13, 2023, 06:44:14 am
content: Quote from: alitronix on June 12, 2023, 10:02:59 pmThese are current transformers for sensing large AC currents and transforming to a lower current for measurement by control circuitry.I would guess that the 1/3000 designation is the transformer ratio - the primary is the one turn through the thick wire and secondary would have 3000 turns. So for 1A in the primary you should get 1/3000A in the secondary when short-circuited or run into a low resistance.You can verify the turns ratio by measuring the inductance ratio between primary and secondary which should be approximately the square of the turns ratio i.e. 1:9,000,000. So for the secondary of 8H you should get about 889nH primary inductance. This figure is far too small to measure easily so you would get a more sensible value by threading, say, 10 turns through the primary side. This should give a primary inductance reading of about 89uH if there is 3000 turns on the secondary.Warning- do not feed any significant current through the primary of a current transformer without a short or low resistance load on the secondary. It can produce high voltages that are damaging to the external circuitry or the transformer itself if not operated with a suitable load.

author: alitronix
author_rank: Contributor
timestamp: June 13, 2023, 06:28:58 pm
content: Thank your response, so they are current transformers what I supposed to be... without called correctly, is more clear now for me after your explanation.do you thing they are custom made? I searched in a lot of online e-shops but not find with this ratio nether with this form factory for PCB mount .they are common in industrial stuff?"Warning - do not feed any significant current through the primary of a current transformer without a short or low resistance load on the secondary. It can produce high voltages that are damaging to the external circuitry or the transformer itself if not operated with a suitable load."yes, I discovered on my skin... this is how I fried one of this ... stupid me ... was too late when i realized what I did , my brain was confused ...

author: srb1954
author_rank: Super Contributor
timestamp: June 13, 2023, 08:27:30 pm
content: Quote from: alitronix on June 13, 2023, 06:28:58 pmI haven't seen current transformers in this form factor before so they could be custom made. However, I don't have wide experience in industrial control systems so my opinion may not be worth that much.You could possibly take the damaged transformer to a transformer winding shop and see if they could rewind it. They may also need the remaining good transformer to measure its parameters to check the repaired transformer against.

author: alitronix
author_rank: Contributor
timestamp: June 18, 2023, 10:57:20 am
content: I checked I my area were I live and nobody do this job anymore, to rewinding transformers, and to send it we need to evaluate much better the alternatives.I made a little search and It seems to be custom TA transformer made back in early 2000 from a local company what is close the doors a few years ago.in a last few years I came across with more and more "small" companies what shutdown the activity, this is a little bit sad .We already replaced the controller but we want to repair this one and keep it like backup. since this type of controller is around 2000 EU/$ , he want to have a second one in case of he need it again.anyway a learned a lot from this experience what is make me more enthusiastic to keep working, because this days is a little bit of confusion in world.thanks for support.