Tan Delta testing of Current Tranformer (CT) - Theory & Practical Procedure

Tan delta test is an AC low voltage dielectric test that is carried out on insulation to determine its health. Tan Delta test is also called as loss angle test or dissipation factor test.
Tan Delta test is carried out on various electrical equipments such as :
1) Current Transformer
2) Potential Transformer
3) Transformer Bushing
4) Transformer Windings
5) Capacitive Voltage Transformer
6) Coupling Capacitor
Purpose:
Detecting incipient weakness in HV insulation
Predicting remaining life of the equipment under test
To get “benchmark reference reading” of the equipment when it is new, clean, dry and free from impurities
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[@truptimali6856]

Thanks Sir for this Informative Video 🙂

[@substationtestingandcommis3452]

So nice of you 🙂

[@sisir22]

very nice elaboration abt tan delta testing, its easy & digestive, pronunciation is very clear. thank you a lot.

[@substationtestingandcommis3452]

Thanks for your appreciation. 🙂

[@angrycap999]

Maa Shaa ALLAH zaberdast

[@kananbiharibehera5749]

Thank you sir,i gain more tips from this video, plz sir upload more video

[@garvalnaran9972]

Good

[@KRISHNAKUMAR-pu9tq]

How tan delta = Ir/Ic
Calculated using this data?

[@fazleazim8125]

great

[@subratamohapatra6478]

Very good lecture.

[@substationtestingandcommis3452]

Glad it was helpful!

[@bibhubisoyi525]

Nice explanation

[@indrajitchatterjee4752]

Helpful.Thank you

[@karanparmar4754]

What is tan delta point and where is it connected ,i am having a hard time understanding it.

[@that90sguy77]

You have to open the CT terminal box under or on the side of the CT

[@surendrakverma555]

Very good 🙏🙏🙏🙏🙏🙏. Thanks

[@user-oi3rk1gm2b]

شكرا

[@sjamesking6605]

Thanku

[@Assistant_User]

Thank you. In which standard appears values of permissible limits shown for Tan Delta?

[@birbahadurpal5080]

❤

[@aviralsingh2776]

Nice man

[@asywadsaferi5565]

Using gst mode do we need to connect to earth?

[@ravikumarkoyyana12]

If tan delta point is not available in CT,then where to connect the Tan delta terminal of the kit

[@substationtestingandcommis3452]

Connect to earthing and take tan delta in GST Mode

[@deesingh3330]

Thank u so much sir for sharing your knowledge 🙏🏻 ..& purely explanation

[@substationtestingandcommis3452]

Thanks and welcome

[@juakoedge]

Thank you for the information, i have a question: The HV terminal must be connected to the primary terminal of the CT, we all know CT's have 2 terminals, usally P1 and P2, do i have to short them, or just connect the HV to P1 terminal?
In terms of secondary windings, theyre shorted and grounded, am i right? i whould be so grateful if you could clear my doubt

[@substationtestingandcommis3452]

P1 and P2 are internally connected, you should not short them.

[@substationtestingandcommis3452]

Secondary windings are connected to meters or relays.

[@therisencomrade3452]

Secondary alrdy connected to meter and relay so, secondary is not open circuit even during tan delta test. The P1 is first remove from the main line only and then the connected to tan delta HV side. P2 is usually left like that since isolator is alrdy open during test(or maybe earthswitch need to be closed?) . I have performed this test once,I think we usually test with 2kV and 10kV at 50Hz and 100Hz frequency. The current being injected inside CT is around 100A.(For 132kV)

[@ashishvitekar3474]

Sir,
When tan delta Test required?
As per your best explanation I realized as same as IR Test done by HT megger.
Can we this test by HT megger?
Thank you very much

[@substationtestingandcommis3452]

IR is not a accurate test for determining the insulation deterioration.

[@substationtestingandcommis3452]

Monitoring trend of tan delta is accurate method.

[@tb.casenjo2680]

in which standard appears this procedure?

[@rushirajsinhsolanki2990]

CT secondary terminal short and measured??

[@substationtestingandcommis3452]

Yes, secondary terminal should be kept short.

[@SaikatJana-b8n]

@@substationtestingandcommis3452 must be shorted & grounded

[@anilshemade6048]

Good info...If ct has no tan delta point,then where the lv lead of the kit be connected?

[@substationtestingandcommis3452]

Connect to earthing and take tan delta in GST Mode.

[@anilshemade6048]

@@substationtestingandcommis3452 ok thank you.

[@CutieSamriddhi357]

@@substationtestingandcommis3452 then earthing

[@therisencomrade3452]

​@@CutieSamriddhi357both connect to earth.

[@vinodmusicprogamer9503]

What if cvt and CT tan delta points are not earthed plz reply

[@substationtestingandcommis3452]

If tan delta point is not earthed, there is high possibility that CT/CVT may blast.

[@CutieSamriddhi357]

If we left the tan delta point in grounded then what happens

[@CutieSamriddhi357]

Ungrounded

[@substationtestingandcommis3452]

Voltage will get developed across tan delta point. CT will burst or get damaged.

[@RAMBABU-gk8kx]

What's UST and gst mode

[@substationtestingandcommis3452]

Ungrounded Specimen Test and Grounded Specimen Test

[@mathewsksamuel6508]

hello bro

[@substationtestingandcommis3452]

Hello..

[@substationtestingandcommis3452]

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[@ashok2m]

Great

[@AnilKumar-bz4rj]

❤