Waross, please read a paper I wrote 30 years ago, wich I have attached in this thread. I think this phenomenon is a "magnetic" not a "electric" phenomenon, and it is not easy to understand.
I know that there is a lot of experts over here that think "out the box" and I hope to get a good explanation.
In my view this inrush current "zero offset" happens due to the assymetry of the iron hysteresis loop which do not returm to zero after core saturation during transformer energization.
What do you think about that?
Waross, the graph plots I posted are correct and there is no external DC bias.
Some researchers think this "zero offset" is due to saturation of the current transformer (CT) used in the measurements. Sometimes it happens.
However, this "phenomenon" can also be seen in transformer energization...
In this new format of Eng-Tips I could not find the figures I had posted.
Please, see attached the figures I had posted before in order to clarify my question.
Hi sushilksk,
"Magnetic flux outside the core" is the flux that leaks from the core when it saturates.
The attached figure shows the magnetic flux leaving the upper part of the core and returning through the lower part.
In general, the path of this magnetic flux includes the transformer tank...
Thanks guys for your thoughts so far!
I think the attached waveform will clarify exactly what I'm asking about the "zero offset" of the inrush current.
Could this phenomenon be caused by the magnetic flux outside the iron core during transformer energization?
Cheers,
Herivelto S. Bronzeado...
Sorry guys, I didn't make myself understood.
Perhaps is due to my "native" Brazilian English.
I'm not referring to the peak inrush current but its "zero".
I know that the zero of the inrush current is not ZERO due to the asymmetry of the hysteresis cycle during energization. My question is...
Hi Guys!
I have observed a "zero offset" in transformer inrush current waveforms.
Some researchers think this "offset" is due to saturation of the current transformer used in the measurements.
However, this "offset" has also appeared in transformer energization simulations.
Does anyone may...
Just to think.
https://res.cloudinary.com/engineering-com/image/upload/v1725071394/tips/Neutral_Current_xhzo4a.pdf
Cheers,
Herivelto S. Bronzeado
Brasília, Brazil
https://www.linkedin.com/in/heriveltobronzeado/
https://www.researchgate.net/profile/Herivelto_Bronzeado
Thank you guys for your imputs so far!
Cheers,
Herivelto S. Bronzeado
Brasília, Brazil
https://www.linkedin.com/in/heriveltobronzeado/
https://www.researchgate.net/profile/Herivelto_Bronzeado
Hi folks!
We are preparing a bid to a big water pump project that includes 6 synchronous motors from 5 MW to 13 MW.
I wonder if somebody could give me some informations about the advantage/disadvantage in choosing the voltages to feed the motors: 6.9 kV or 13.8 kV?
Thanks in advance.
Cheers...
Hi Folks,
See annexed what I have got in the J&P Transformer Book.
Cheers,
Herivelto S. Bronzeado
Brasília, Brazil
https://www.linkedin.com/in/heriveltobronzeado/...
Hi folks,
In a simulation of energizing two similar transformers at the same time, the inrush current is not twice the value of the inrush current of just one transformer (in the same conditions).
I wonder if the experts could give a explanation on that "phenomenon". Thank you!
Cheers...
Hi davidbeach,
In the company I worked for, there is a electrical system on 69 kV that are supplied by a transformer wye-delta 230/69 kV. A zig-zag transformer is used to give a ground reference to the delta system (69 kV).
When the zig-zag transformer is out of service, the delta system...
Hi folks,
If the electrical system is floating, how can the voltage (to "ground") will normally be measured?
Cheers,
Herivelto S. Bronzeado
Brasília, Brazil
https://www.linkedin.com/in/heriveltobronzeado/
https://www.researchgate.net/profile/Herivelto_Bronzeado
Tony2802
Please, have a look in
Cigre Technical Brochure 568 - "Transformer Energization in Power System: A Study Guide",
February 2014, Report number: TB 568 ISBN : 978-2-85873-263-0
Cheers,
Herivelto S. Bronzeado
Brasília, Brazil
https://www.linkedin.com/in/heriveltobronzeado/...
Hi RRaghunath,
Thank you for your imputs.
Sorry! I have no experience on synchronous motors running as I was out of the Project when it started to operate. I have just returned to it.
The motors that are running just now are 6,9 kV synchronuos motors from 2.2 to 13 MW. I will see how they...
Thanks Keith, for correct me!
Do you think we will be happy on that?
Cheers,
Herivelto S. Bronzeado
Brasília, Brazil
https://www.linkedin.com/in/heriveltobronzeado/
https://www.researchgate.net/profile/Herivelto_Bronzeado
Thank you Gr8blu!
So far, I think we are heading to 6,9 kV synchronous motors.
Cheers,
Herivelto S. Bronzeado
Brasília, Brazil
https://www.linkedin.com/in/heriveltobronzeado/
https://www.researchgate.net/profile/Herivelto_Bronzeado
Hi Keith,
I'm afraid but I think you are (politically) right!
Cheers,
Herivelto S. Bronzeado
Brasília, Brazil
https://www.linkedin.com/in/heriveltobronzeado/
https://www.researchgate.net/profile/Herivelto_Bronzeado
