This sounds a bit like a FIDVR situation where the source will not support the load with inrush. In other places, it is largely from starting highly inductive loads like air conditioners or motors where the start current is many time the load current. this sounds like much more than just...
This in general is a normal operation for reclosing in utility systems after a fault and clearing it. The harmonics and long inrush conditions that others are talking about is one where there is no load on the system. The condition you describe seems to be rather normal and inrush is high...
Multiple transformers in series are more complex to analyze as they may have multiple residual flux conditions in the various cores. the resonance conditions can last for quite some time as the paper referred to indicates.
While point on wave closing is a theoretical way of mitigation of these...
As you have already figured out, the possibilities are numerous. An EMPT study should help but most likely looking at fault recorder events and wave forms will give a hint as to where to start. Many relay types record these fault events in their memory.
It is new to me that there is a limit to the number of time or the time required between energizations. If done correctly when using a soft switching technique, there is no limitation and inrush currents are controlled hence does not cause transformer damage. Conventional vacuum breakers will...
The inrush is generally caused by energizing the interconnection transformer to the grid. When this is energized, the inverters come on line rather seamlessly.
Yes, this inrush of the transformer can cause significant voltage dips. This is true for battery storage installations as well as...
Yes indeed estimating inrush can be very complex but there are some simple rules of thumb that will assist. One such technique is in the link below.
https://www.southernstatesllc.com/applications/connecting-solar-to-the-grid
The amount of time for the resonance of the inrush depends on the...
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I have been hearing about this issue and in particular on solar farms and renewable connections. Is this still an issue in the industry?
It is starting to sound like it is more than just transformer inrush causing the problem. If motors are stalled, they do indeed have high starting currents and they can be there for several seconds, hence causing FIDVR as was discussed earlier in this thread.
Is it just transformer inrush or...
Is you issue blowing fuses or reducing voltage dips? I would suggest looking and trying out the link in my earlier post. It is focused on evaluating voltage dips.
One customer had the issue of blowing fuses and this was resolved with the Transwitcher of Southern States. This link will show...
Yes these peaks indeed can be very high indeed. They can last several seconds depending on circuit conditions although these inrush currents are single polarity rather than a true RMS waveshape. The longest times they exist are where there are multiple transformers of similar size on the same...
There are cases where the inrush current exceeds that calculated by transformer impedance. This is when there is residual magnetism in the core. This residual magnetism is a common occurrence but if frequently ignored because it usually is complicated to simulate accurately. It is real...
