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...
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,
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 Folks,
In the first stage of a big water project, it was specified 6,9 kV synchronuos motors (2 to 13 MW) to run the water pumps. These pumps are supplied by 230/6,9 kV transformers fed by a dedicated 230 kV radial power system (150 km) with several susbtations.
Now, there is a doubt about...
Hi folks,
I wonder if someone has experience in using series capacitors (BCS in the diagram below) to start big induction motors (around 13 MW) in a pumping station.
What kind of caution I should to take into account?
Cheers,
Herivelto S. Bronzeado
Brasília, Brazil...
Hi folks,
Please, find attached a double busbar configuration where the circuit-breaker that connects the busbars does not exist and the busbars connection is make by a normal disconnector, which is wearing out quickly.
The questions are:
1. Why this happens (disconnector wearing out so...
Hi folks,
Returning after long time away from the electric sector.
The question is: "Are the electric vehicles really sustainable?"
Sorry if this was discussed before.
Best Regards,
Herivelto S. Bronzeado
Brasília, Brazil
https://www.linkedin.com/in/heriveltobronzeado/
Hi folk,
Is there a diference between the secondary voltage signals from an inductive a capacitive instrument transformer during a de-energizing of a system to which they are connected?
Best Regards,
Herivelto S. Bronzeado
Brasília, Brazil
https://www.linkedin.com/in/heriveltobronzeado/
Dear Colleagues,
I wonder if somebody could tell me if there is any galvanic corrosion between two metals (say Al and Cu)in vacuum.
As far as I know, there would have to be an electrolyte to form a complete electric circuit in order to permit the electrons flow.
Merry Christmmas!
Herivelto...
Hi folks,
A 5.5 MW, 6.9 kV synchronous motor did not start when it is energized. Then we moved the rotor position and the motor starts. We have observed that the motor only runs if the rotor is in a particular position.
I wonder if anybody has faced a problem like that.
Best Regards...
Hi folks,
Considering a two winding, 13.8/230kV step-aup transformer feed by a generator under a conditions of a 180o out-of-phase synchronization:
1. What about the directions of the windings currents? Are there oposite to each other as during a short-circuit?
2. Is this condition worse...
Hi folks,
Anyone has faced problems with transformer out of phase switching?
Is this condition worst than a three-phase short circuit?
Considering a two windings transformer, what about the sense of the winding currents during this condition? Opposite, like in the short circuit condition...
Hi folks,
What about the idea of getting power and simultaneously reducing evaporation by using solar panels over very long water canals?
Advantages and disadvantages.
Best Regards,
Herivelto S. Bronzeado
Brasília, Brazil
http://www.linkedin.com/profile/view?id=46319837&trk=tab_pro
Hi folks,
What about the idea of getting power from solar panels under HV transmission lines?
Advantages and disadvantages.
Best Regards,
Herivelto S. Bronzeado
Brasília, Brazil
http://www.linkedin.com/profile/view?id=46319837&trk=tab_pro
Hi folks,
In our water supply project (PISF) each 230/6.9 kV substation feeds a pump station that is 200 m away. The substation and pump station have separated earth systems. The 230/6.9 kV transformer is delta/wye-grounded connected.
Is it necessary to connect these two earth systems? If...
Hi folks,
We need to specify a system to start large synchonous motors driving water pumps. The motors are between 5 to 13 MW at 6.9kV. They are feed by a transformer 230/6.9kV, two motors per transformer.
Is the SCR soft-starter the best system for this application?
Thank you in advance for...
Dear colleagues,
In the past, DC filters were required in HVDC systems to avoid telephone interference, which may be caused by the DC line harmonics.
Nowadays, with all new telephone tecnologies, are these DC filters necessary?
Best regards,
Herivelto S. Bronzeado
Ministério de Minas e...
Hi folks,
In the past the maintenance people of my company used to disconnect CTs, PTs and SAs (Surge Arrester) with the system energized. Today this is not allowed.
I wonder if somebody in this forum has experience in this kind of work or can guide me to get information obout it.
What kind...
thread238-237001
Dear desertfox an prc,
Regarding the thread above, please, find attached a photo of the connection that has failed during a short-circuit.
As you can see, some wires of the cable has been melted due to the connection temperature. My question is: if the previous thermography...
