It is the ratio of reading taking after 15 or 30 seconds to reading taking after 60 seconds with same coonection as your video. Both readings are taken in one step. The purpose of this test is to ensure integrity of the winding insulation.
Nice work - thank you for posting this video. In the calculations you compensate based on room temperature. Should you instead be compensating for transformer oil temperature.
You are right. In this video, for simplification ambient temperature is used. However for accurate calculation, the transformer oil temperature must be used, Thanks for your valuable comment.
For a High voltage i.e. 220kV or 500kV transformer, the megger testing set rating must be 5 kV. For medium voltage i.e. 11kV, megger set of 1kV rating is OK.
It's OK to say that any transformer is safe to operate at 20 Celsius, but what if the manufacturing company knows that the transformer is going to be subjected to ambient temperatures much hotter than 20 Celsius? Isn't it better to apply the IR test for the maximum operating temperature. For example, if the transformer is being used in hot summer climates where the temperature regularly reaches 35 Celsius, shouldn't we apply the test for 35 Celsius to make sure there will be no arcing at all times of the year?
Thanks. As someone practically associated with sub-stations and T/Lines, I would suggest to study updated articles from the internet as the testing sets are evolving with time.
It's used practically in most cases. Not shown here to avoid any confusion for new learners. Guard terminal is a way to minimize the interference from unwanted circuits. So e.g. if we are measuring insulation resistance between primary and ground, we will have to guard the secondary terminal of transformer.
Input source is the megger testing set which has built-in battery (in case of electronic set). While in case of old hand operated manual megger testing set, voltage is produced by rotation of crank.
if DAR less the 1 it is dangerous need for maintenance if ration greater then 1 and less then 1.3 the check oil BDV mositure contents and C & DF test of winding if the ratio greater then 1.3 it is good
As per insulation resistance minimum requirements for a transformer, for each kV atleast we must have 2 Mega Ohm resistance. so based on this, you can calculate minimum insulation resistance requirements for any rating transformer. that will turn out to be in Mega ohms in most cases
Superb detailed videos,that every videos should have.
It is the ratio of reading taking after 15 or 30 seconds to reading taking after 60 seconds with same coonection as your video. Both readings are taken in one step. The purpose of this test is to ensure integrity of the winding insulation.
It is really a very helpful video. It has cleared all my doubts. Thank u sir.
You are welcome and thanks for ur valuable feedback.
Nice Explanation point to point...Will wait for next video.. Quality video..
thanks for appreciation. More videos coming soon. Keep in touch.
Nice work - thank you for posting this video. In the calculations you compensate based on room temperature. Should you instead be compensating for transformer oil temperature.
You are right. In this video, for simplification ambient temperature is used. However for accurate calculation, the transformer oil temperature must be used, Thanks for your valuable comment.
What voltage are you setting the megger to for each test H-XG X-HG and HX-G ?
For a High voltage i.e. 220kV or 500kV transformer, the megger testing set rating must be 5 kV. For medium voltage i.e. 11kV, megger set of 1kV rating is OK.
Please give the reference informations in detail that where did you get it.
Very informative indeed 👍
Thanks for appreciation.
It's OK to say that any transformer is safe to operate at 20 Celsius, but what if the manufacturing company knows that the transformer is going to be subjected to ambient temperatures much hotter than 20 Celsius? Isn't it better to apply the IR test for the maximum operating temperature. For example, if the transformer is being used in hot summer climates where the temperature regularly reaches 35 Celsius, shouldn't we apply the test for 35 Celsius to make sure there will be no arcing at all times of the year?
I love the explanation
thank you so much for your helpful videos
Thank you sir🙂 ,this is very helpful .
Thank you sir for your educational video.
You are welcome. Keep in touch for more educational videos related to practical Electrical Engineering.
What is the resistance value at a temperature of 40 degree celcius
What is the need of shorting the hv yet it is delta ?
How do we adjust the temperature of the oil of the transformer
is the 20 ' c the temperature of winding of the ambient temperature ,
another thing would this work with dry transformers ?
thanks
How dovi test for the temperature of the transformer oil
Informative, Thnx sir.
Nice work. What books do you suggest about this topic?
Thanks. As someone practically associated with sub-stations and T/Lines, I would suggest to study updated articles from the internet as the testing sets are evolving with time.
Can you please make videos on testing of power cables
Sure. I will upload soon IA.
nice work.
3:04 isn't it 500kOhm ?
You are right 👍
why did not you use guard terminal.
It's used practically in most cases. Not shown here to avoid any confusion for new learners. Guard terminal is a way to minimize the interference from unwanted circuits. So e.g. if we are measuring insulation resistance between primary and ground, we will have to guard the secondary terminal of transformer.
@@theengineeringpower4213Could you please explain in more detail? What do you mean by 'to minimise interference from unwanted circuits'?
How the input supply is injected for testing of transformer?. Input source
Input source is the megger testing set which has built-in battery (in case of electronic set). While in case of old hand operated manual megger testing set, voltage is produced by rotation of crank.
Helpful
if DAR less the 1 it is dangerous need for maintenance if ration greater then 1 and less then 1.3 the check oil BDV mositure contents and C & DF test of winding if the ratio greater then 1.3 it is good
Thanks!
Dielectric Absorption Ratio (DAR) Test insulation test ruther then IR test
Tnx
DAR b/w HV to LV, LV to G , HV to G
Major Farts 🤣
Subtitles :)
Insulation Reating of Einding must be not lower Than 10Giga ohms not in mega
As per insulation resistance minimum requirements for a transformer, for each kV atleast we must have 2 Mega Ohm resistance. so based on this, you can calculate minimum insulation resistance requirements for any rating transformer. that will turn out to be in Mega ohms in most cases
@@theengineeringpower4213for each KVA or KV?