HOW TO SIZE A TRANSFORMER !
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- Опубліковано 9 жов 2024
- Electrical transformers are used in everyday life.
A transformer is a passive electrical device that is used to increase the voltage level at the power generating station (Step up) or to decrease the voltage level (Step down) for Electrical power distribution purpose.
Transformer sizing is a very important step and we must make informed decisions regarding proper transformer sizing and its impact on the electrical system under different operating and loading conditions
This video explains in detail the steps to be followed for the kVA calculation of a Transformer.
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Link for video on "Understanding Electrical Load Schedule" • UNDERSTANDING ELECTRIC...
Why is it important to size a Transformer Correctly!!
1. Higher costs due to oversized transformer, conductors, and Circuit breakers in case an oversized transformer rating is selected.
2. Larger transformer KVA Rating will result in higher fault level (assuming the same transformer impedance), which will require increased CB rating as well as increase in the maximum interrupting current.
3. In case of an undersized transformer KVA rating, it may create issues within electrical distribution systems, including loss of loads and voltage drop during starting of large motors may exceed the acceptable limits.
The starting point of the Transformer Sizing is the load that will be supplied by Switchboard/Panel that will be fed by the Transformer.
Peak Load (PL) should be used for this purpose. PL is obtained from the Electrical Load Schedule.
We should not use Connected Load for transformer kVA calculation as it will be result in an oversized transformer.
Once the Peak Load is known, the Transformer kVA rating is calculated by adding this Peak Load and the expected Future Growth
Future Growth is normally considered between 10% - 30% depending on what additional loads are expected in the future.
One of the best video found on youtube on this topic...the way u explain ...hats off to u sir.... Thanks
Thanks. Glad that you found the video useful. Please let me know your comments on my other videos. Please do subscribe to my channel and share with your friends.
Great video
This is a good example of sizing of machines with calculation.Very helpful for all interested,whether a student,practicing engineer or non engineers but managing the show of the business.
Thanks a lot !!
Please post a video for how size a breaker/switchgear
Superb Explanation ❤ any one can understand if he give some time to watch carefully ❤
Thank you so much 😀
This is a very practical guide for calculating the KVA rating of a transformer at any electrical installation.
At any electrical installation,transformer has a unique importance.An underrated one can wreak havoc;whereas an excessively over-sized one will involve an escalation in first cost as well as in maintenance cost.
The factors involved,assumptions and the examples are very clearly depicted here with numerical figures and the calculations in an involving and lucid way.Highly helpful for present and future engineers and managers of enterprises.
Thanks for your comments.
You are video is simple supper..but in continuation to this if you would have done sn example. With many loads ..it is simple super
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Very detailed and informative video of transformer sizing. It is going straight to my favorites. Please keep making more such informative videos.
Good day, many times I played this video and make research on standards, i did it bec. It's quite interesting and with clear steps of calculation just to say we can depend on!!!.so far I have doubt about the 15% voltage drop at high motor terminal. Applicable fire pump..can you please help to clarify...thank you
Please make a video on generator sizing with motor starting.
Thanks. Glad that you found the video useful. Please let me know your comments on my other videos. Please do subscribe to my channel and share with your friends. Videos on the above topics are under preparation and will be uploaded shortly.
Your all videos are good.. kindly make a video on generator sizing
One of the best.....
Thanks. Glad you liked it.
This is a great way of explaining important topics in the most lucid way! It will help a great deal in understanding. Much appreciated efforts!
Great to hear!
@@theelectricalsolutionschan1095 please explain the value of j in peak load calculation.?
thank you for this awesom video. well explained
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Thanks for your valuable efforts and quality content for educating us..
We expect more such content from you in future..
Thanks. Glad that you found the video useful. Please let me know your comments on my other videos. Please do subscribe to my channel and share with your friends.
Very clear and simple explanation. Thank you very much.
Glad it was helpful!
Nice video. Would you please make a video of generator sizing. Keep up the good work.
Thanks. Glad that you found the video useful. Please let me know your comments on my other videos. Please do subscribe to my channel and share with your friends. Video on Generator Sizing will be uploaded shortly.
This video is excellent and easy way to understand all, we are expecting more from you in electrical design 👍👍
Thank you, I will
Excellent 👍
This is one of the best explanation for trafo sizing. Thank you for the nice video. Expecting more to come.
Glad you liked it! more to come
Thank you !
Thanks. Glad that you found the video useful. Please let me know your comments on my other videos.
Awesome Video Mr. Anil Sahay👌
Thanks !!
Nice, but i get lost in per unit application formula, can you share per unit fomulas, thanks
Still we will apply 6 tines starting if large motor under vfd controls?
Could you clarify with the information about the which are the actual values used to calculate the PU impedance. i am not able to follow from where/which data is used to derive the ZT, ZM and ZL.
Thanks for your comments.
As explained in the video,
ZT = p.u impedance x (Base MVA/Trafo MVA)x (Trafo kV /Base kV)^2
replacing these values indicated in the video, ZT is calculated as 0.03pu.
Similarly, for other impedance values.
Hope this is clear now.
Thanks for the valuable information.
Can you please make a video on Transmission Line modeling especially Long Transmission Lines. Thanks alot
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I have doubt on how you calculated the final impedance, since both the impedances are parallel, the formulae must be Z1*Z2 by Z1+Z2 na..
Remaining everything is crystal clear for me..
Thanks for your efforts..
Thanks for comments.
I have checked the sum of parallel impedance Z2 = ZM II ZL, and it has been correctly calculated as Z1*Z2 by Z1+Z2
Z2 = 1.57833*0.54367/ (1.57833+ 0.54367)
= 0.40438 p.u
very clear explanation.expecting good videos of such a nature in future.lot of thanks.
Glad you liked it..keep watching
If ZL = Base Load Imp / Base Impedance = 0.0886/0.16 = 0.55375 p.u.. why did you obtain 0.54367 p.u ???
Can I use these steps in sizing of a transformer of a building in case I need it
Thanks for your comment. Yes, the same steps can be used.
Thanks a lot for a very short but informative video. This was very helpful. Please make such videos
Thank you. Glad that it was hopeful. Please keep visiting the channel for more such videos on Electrical topics.
This video is very easy to understand and very helpful.
Does anyone know the standard that states 150% overload and 15% voltage drop when the motor starts?
Thanks for your email.
IEEE std 57.91 /IEEE-242/ IEC-354 & IEC-90 should be used for guidance regarding loading of transformers. In case of overload during motor starting, it will be for a very short duration (during the period of motor starting only). Till what percentage we can overload the transformer will depend on the ambient temperature and the duration of overload.
Regarding voltage at motor terminals, it may be noted that NEMA requires that motors shall be able to start successfully at 85% of nominal voltage. Please note that Torque is proportional to square of voltage. Any further decrease in voltage will have huge reduction in starting torque.
Nice video. Keep it up!
Thanks. Glad that you found the video useful. Please let me know your comments on my other videos.
Brilliant
Sir, how to size transformer for 3 incomer 2 bus coupler
Sizing of a transformer is dependent on the load being fed by the transformer and not on Incomer /Buscoupler combination. In your case, for example, if the 2 Incomers are normally sharing the total load and the 3rd Incomer is just a standby incomer and switched ON in case of failure of any of the 2 Incomers, then the transformers should be sized to carry half of the total load.
Im just confused in addc regulation with regards to bus coupler. Some design is 2 incomer 1 bus coupler however the transformer is sized on the individual bus and if incase 1 tx fail you need load shedding.
Nice discussion & explanation..thanks
Brother, I have total load of 70 kw (01 motor = 60kw and other 10 motors =1 kw each) and all the motors will have to start at same time. What will be correct kva rating of transformer? Distance of transformer to motors is 350 meters.
The starting KVA requirement of the 60kW Motor will impact the Transformer rating. Please calculate accordingly.
Hi, could you please give me an instrument used in measuring the transformer gap length
Please consult a testing equipment supplier for this...
11:58 @ Base MVA how to calculate 1 MVA
@ please make a video on kva formula in terms of kw + j kvar. What is the value of j here. How to convert kva value in terms of kw+ j kvar. Please explain
Thanks. Will try to produce a video as requested.
What values you have taken to calculate ZT?
Thank u sir..good explanation...please do DC system detail explanation...
Thanks for your comments. Glad you found it useful. Do let me know what you would like to be explained in DC system.
@@theelectricalsolutionschan1095 Regarding battery and charger sizing calculation for any plant
Noted...will try to do a video on the topic in future
Great effort 👏
Thanks a lot 😊
Welcome 🤗
Understand. But how to you calculate kw +j kvar?
kVA = kw +j kvar
kVA = Sqrt [ (kW)^2 + (kVAR)^2]
Can you explain the details of calculating ZT(impedance of transformer)?
Transformer Percent Impedance (Z%) is provided on the transformer nameplate.
Impedance is the current limiting characteristic of a transformer and is expressed in percentage.
Percentage impedance of a transformer is the percentage of the rated voltage applied at one side (primary winding) to circulate rated current on transformer keeping its other side (secondary winding) under short circuit conditions.
Why didn't you consider efficiency and safety margin
The presentation is just to demonstrate how we arrive at the transformer KVA rating.
When considering a transformer selection, it is important to understand exactly how transformers work and what contributes to their efficiency.
A sign of inefficiency is the presence of excess heat. Any heat generated by a transformer is a direct result of inefficiency and losses within the transformer. Some of the key contributing factors to transformer inefficiency are copper and iron losses. Hence, a more efficient transformer would mean lesser losses.
With respect to Safety margin, the actual project considerations, future growth, etc need to be taken into account to decide the margin.
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