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Electrical Chakra
India
Приєднався 24 лют 2014
A basic guide to Electrical Engineering, electrical testing & protection philosophy.
Insulation resistance test with examples of surface leakage current flow causing wrong/low I.R value
Please get the theory part as discussed in my previous class-
ua-cam.com/video/ED0EfAwoHjk/v-deo.html
I.R = V(Applied)/I(measured)
The guard terminal of an I.R testing kit is used to track the the surface leakage current of the insulator if applied with a high voltage source (DC).
The higher the surface leakage lower is the I.R value if the guard terminal is not connected.
This procedure is also followed in testing of cables.
We in this video have tried to describe the effect of this surface leakage current.
To reduce the value of surface leakage currents we need to clean up the surface of the insulator (As applicable).
Insulation resistance (IR) testing conditions are generally dictated by the system under test and any time constraints the user may have. IR testing is based on a fairly simple concept - apply a voltage between the cable conductor and earth, measure the leakage current and subsequently calculate the IR.
Heating appliances should have a current that should be less than 0.75 milliamps per Kilowatt up to a max of 5 milliamps. Portable/handheld appliances have to have earth leakage current of less than 0.75mA to be considered safe.
In routine testing DC voltage is applied against an insulator to measure "Insulation resistance".
The testing discussed
herein predominantly concerns DC voltage testing.
When a voltage E (Volts, V) is applied, current flows
through the cable insulation. This is known as
leakage current Ileak which in turn, according to
Ohm’s law, provides the IR such that,
IR =
𝐸/
𝐼leak
However, the current measured by an IR tester is
the total current Itotal which includes capacitive and
absorption currents Icap and Iabs, respectively, in
addition to Ileak where,
𝐼total = 𝐼leak + 𝐼cap + 𝐼abs
and,
IR =
𝐸/
𝐼total
I.R = V(Applied)/I(measured)
ua-cam.com/video/ED0EfAwoHjk/v-deo.html
I.R = V(Applied)/I(measured)
The guard terminal of an I.R testing kit is used to track the the surface leakage current of the insulator if applied with a high voltage source (DC).
The higher the surface leakage lower is the I.R value if the guard terminal is not connected.
This procedure is also followed in testing of cables.
We in this video have tried to describe the effect of this surface leakage current.
To reduce the value of surface leakage currents we need to clean up the surface of the insulator (As applicable).
Insulation resistance (IR) testing conditions are generally dictated by the system under test and any time constraints the user may have. IR testing is based on a fairly simple concept - apply a voltage between the cable conductor and earth, measure the leakage current and subsequently calculate the IR.
Heating appliances should have a current that should be less than 0.75 milliamps per Kilowatt up to a max of 5 milliamps. Portable/handheld appliances have to have earth leakage current of less than 0.75mA to be considered safe.
In routine testing DC voltage is applied against an insulator to measure "Insulation resistance".
The testing discussed
herein predominantly concerns DC voltage testing.
When a voltage E (Volts, V) is applied, current flows
through the cable insulation. This is known as
leakage current Ileak which in turn, according to
Ohm’s law, provides the IR such that,
IR =
𝐸/
𝐼leak
However, the current measured by an IR tester is
the total current Itotal which includes capacitive and
absorption currents Icap and Iabs, respectively, in
addition to Ileak where,
𝐼total = 𝐼leak + 𝐼cap + 𝐼abs
and,
IR =
𝐸/
𝐼total
I.R = V(Applied)/I(measured)
Переглядів: 414
Відео
Stability test of transformer
Переглядів 9 тис.Рік тому
Transformer Stability Test Procedure OBJECTIVE: The Purpose of Differential Stability test is to determine the Healthiness of the Differential CT circuits which is protecting the in Zone equipment from actual fault conditions and through fault conditions. This scheme monitors the fault condition (i.e; In-zone or out-zone) and trips the power circuit accordingly. If the internal fault (In-zone f...
Generator Differential Protection 87G
Переглядів 1,4 тис.2 роки тому
This video is about the generator differential protection. One of the fundamental laws of electric circuits is Kirchhoff’s Current Law, which states the algebraic sum of all currents at a circuit node (junction) must be zero. In a differential protection circuit the CTs are used at both the terminal and neutral point are supposed to be of same CT ratio. Although they are of same ratio and other...
Tan delta testing and it's basics including safety instructions
Переглядів 16 тис.3 роки тому
It's the basic guidance for tan delta test. Tan delta = Ir/Ic That is the basic equation. Everyone knows this equation. What I wanted to focus on is the basic concept of insulators to which acts as a capacitor. Basic equations- - tan δ or D.F = IR/IC - P.F = IR/(IR IC) Acceptable value of tan δ ≤ 0.007 or 0.7% AT 20̊ C tan δ test can be carried out on following equipments- - Cable - Transformer...
How to calculate the setting of a transformer differential protection 87T
Переглядів 16 тис.3 роки тому
#How to calculate the settings of a transformer differential protection. - This video is dedicated for the setting calculation part for the differential protection of a transformer (87T) keeping in mind that the engineers are having some of the basic knowledge about the same (Basic knowledge from college lectures/books). This video will be continued with some more parts/session which will be co...
Insulation resistance and polarization index of insulation (IR & PI)
Переглядів 2,3 тис.3 роки тому
Insulation resistance & polarization index is the diagnostic tool for the basic health checkup of any insulation medium. The basic information about insulation and 4 categories of flowing current through it during the IR test has been described thoroughly. Megger gives required direct (DC) voltage across the insulator, and it also shows the resistive value of insulation directly in M - Ω and G ...
Percentage impedance of transformer
Переглядів 2,6 тис.4 роки тому
This video is basically to define the % Impedance of a transformer along with all the basic calculations to find it out and the usage of the same. This video also contains the relation between Fault current & % Impedance of a transformer. The upcoming video will be on Differential protection. You can contact me on : souravc66@gmail.com
Over current and earth fault protection part-3
Переглядів 8334 роки тому
Over current and earth fault protection part-3
Over current and earth fault protection part-2
Переглядів 9444 роки тому
Over current and earth fault protection part-2
Over current and earth fault part-1
Переглядів 1,4 тис.4 роки тому
Over current and earth fault part-1
Superb explanation sir....
Weldone boyes
very nice practical example, Dada ! plz make video on hipot withstand & other high voltage test
Your next videos?
Great explanation
Please sir it's a humble request ref stability calculation video upload karo sir
0.7
teacher
Sourabh da ❤👍👍👍
Khub bhalo Dada… tada tadi 😊
Well explain, Thnx sir.
Very nice explanation. one of best I found on this platform. I really respect your effort 👌
Hello Chakra Khan, sample IFLA Generator 100 Amp, When setting i diff is 25 % In in Generator 87G, it is 0.25x100 Amp, What is In mean in 87T? In is low side or HV side transformer FLA?
I can't understand the language spoken but very well explained and illustrated. Hope you can make a video explaining line-line fault current distribution of an unloaded wye-delta and delta-wye transformer. Thank you.
Khub bhalo
Khub bhalo Sourabh Sir
Nice Video, how about the Slope 2 and 3?
what is handbook use it sir?
I’m honestly feeling privileged to know this man personally and being mentored by him. Great video, sir 👍🏻
Expecting more videos, from this series topic
Sir your way of teaching is very nice but some time your voice Not clear during lecture
all over okay but sound problem
Keep more information about electrical motors Pump related Videos
❤❤❤❤❤ wooow great experience
Sir next part kab aayega
Dada tan delta Ka 3 mode Kiu use karta h
Best ever explained on you tube ....sir....I want more videos regarding Transformers all testing with details....like magnetic balance, winding resistance, seperate source, induce over voltage, no load, load loss, Impulse, PD etc (all test regarding Transformers).....plz plz....
Sourabh sir ... remember me? I'm Koushik forom nova air....great sir 👍
Chalei jao boss...
Very nice video sir
Sir very nice 👍👍
Teaching should be like this. Very detailed and simple explanations to be understood. Even I, being 1000 miles away from engineering , could understand. Great work sir.
Bahut badhiya sir ji
Audio back drop so no good
Sir please make a video about ht motor thermal calculations .
Bhot behtreen sir
Very nice illustration and important to find out percentage z, thanks a lot 👍👍👌
Why tan delta point is earthed?
Excellent illustration about insulator, thanks a lot 👍👍
बहुत ही अच्छा
Very Nice explanation
Sir I have husge question on Differential protection . Can u help me ? I Want your mail id .
souravc66@gmail.com
Very good. Thanks 🙏🙏🙏🙏🙏
Good sir 👍
What is the working principle of digital insulation resistance tester sir
Digital insulation tester is having a battery set inbuilt in it and voltage trippler or quadruppler circuit to increase the voltage and then it's as per the wheatstone bridge principle.
Hotath tor channel ta dekhte pelam, good job, keep it up.
Thanks
Very nice explain and very informative video's keep it up. Thank you very much
Your video is so much helpful for a working engineer which I am unable to express in words in this comment box please make video on regular basis.
But why transformer setting is more than 20% to 25% ,while Generator setting is 10% only. ????
It's described in the following link ua-cam.com/video/QvaJBgcNVQ8/v-deo.html
Superb sir