I believe we are saying the same thing. The cable size depends on the transformer's primary current — my point is that it is indirectly dependent. It is directly dependant on the protection size. The cable size changes if the protection size is selected at 125%, 150%, 175%, 200%, etc...
ben...
The cable is sized for the protection, not the transformer full load rating. For example, if your fuse is 30A, you need to size the cables for this value.
In other words, calculate the protection first, then the cable size.
ben
bengibb.ca
powerdesignerpro.com
I've been down the rabbit hole on this sizing. It was good for my understanding but I'd recommend not doing that. Just stick to the recommendations of the relay manual. It's not so much saturation that is the concern but rather mismatched CTs (saturating at different times, etc.).
ben...
I assume you mean flex bus?
If so, follow the manufacturer's specifications for ampacity. I've used Nvent Eri Flex Bus before and it's been good. Expensive, but easy to install and a good product.
https://www.nvent.com/en-ar/eriflex/products/nvent-eriflex-flexbus-conductor-0
ben
bengibb.ca...
I wouldn't recommend oil-filled inside. The fire suppression due diligence and insurance paperwork would be a nightmare. I'd look at two 3-4 MVA dry-types. The manufacturers may be able to do a 7.5MVA dry-type too. Better lead time with dry-type as well I believe.
ben
bengibb.ca...
I can't imagine a generator that operates less than 45Hz. Variations in speed are typically 2-3 Hz from the fundamental frequency (50 or 60Hz, depending on where you are). But maybe I'm misunderstanding the application.
Regardless, I've found the Phoenix Contact power meters (EEM series) were...
I'm trying to follow the IEEE 605 example for calculating the cantilever force on a rigid bus insulator due to short-circuit. I understand the example with the exception of how they determined the equivalent forces (F1, F2, F3 in Figure F.2) from the Fsc.
Example:
F3 = 3 x Fsc_corrected * L /...
Are you already planning to have the SEL-751s for protection purposes? If so, then they could do the ATS logic with no problem. If not, an SEL-751 for just logic purposes is an expensive solution.
Typically those low-voltage DS breakers come with integrated LSIG protection, no? Just confused...
I'll build on a couple of points that have been mentioned.
My First step would be to the utility, as they may dictate what is required and then you are over halfway there. The other half is what the inverters require. Depending on the manufacturer, you may get lucky in talking to an engineer...
I find the PSRC Excel sheet is a great visual, but doesn't actually tell you "does the CT saturate" or give Vs=?? for a given fault current. As such, I'm looking to confirm the right formulas myself (going back to the original question in this thread).
Hi Kiribanda. My intuition is the same as yours. But I would like to show through math/formulas, which brings me back to the root question. I'll need to prove that moving to 800:5 or 1200:5 will work.
Hi!
I want to determine if my 600:5 CT will saturate. I have all the information but I feel like my formula is not correct. I understand it to be:
Vs = ( Ifault / CTratio ) * ( Burden of CT and leads and relay ) * ( 1 + X/R )
Where,
Vs = is the voltage developed on the secondary of the CT...
