Hi Majesus
How do you calculate the short circuit current with ETAP where you have to select either 1/2 cycle or 5 cycle option. Namely, this should depend on the protection device.
I also appreciated that you read the help lines of the software provider to see who does what.
thanks
Any one knows why there are tertiary delta winding used in wind farm substations? For harmonic cancellation or kVAr compensation? It seems to me that the PF regulation is done on the LV side of the same transformer which is 25kV or 34.5 kV. Seems to me this is mainly for harmonic cancellation...
If we follow NEC, there is no permission for reducing the Class I Division I requirements. But according to the API 500, the area classification for gas can be eased up from Class I Division I to Class I, Division II, if the area is adequately ventilated. “Adequate ventilation” is defined in API...
ScottyUK and Apowerengr:
Yhank you for reply. I guess, I have to contact the suppliers as you indicated. I did not want to ask this question if it would not be worth to do so
The transformer is already equipped with ONAF (fan cooling). I will keep you posted this week. Thank you for your time...
I have one application where I may have to replace existing 3750/4687 kVA, 13.2/4.16 kV, 55/65 deg C rise, ONAN/ONAF transformers with 5000/6250 kVA ones.
The problem is space. The existing transformers are using above ground bus duct. Basically, I am restricted with the existing length of the...
I have once discussed this issue. I guess it depends how much you rely on this emergency generator when the time comes. In other words, you may want to test the generator(s) with the real load as a complete package (transfer switch, regulator, etc)
I believe not since (I am thinking) as long as we keep the oil temperature same (55 deg C or 65 deg C rise whatever it is) then the life expectancy should be the same. Am I right here?
Maybe the overall losses would be increased exponentially..
Anyone can comment? Thank you again….
Does anyone know a simple formula for calculating the transformer ballpart price? I need to know a 5 MVA, 13.2/4.16 kV oil filled transformer price. One time someone told me a formula which was partly based on copper price. Thank you in advance....
I have not determined the protection setting yet. We are using Siemens 7UT protection relays. If I am following your advice then the maximum load cannot be bigger than the transformer rating. In this case, I am multiplying the transformer secondary current with 1.25 regardless of my protection...
The secondary current of 5/6.25 MVA transfomer @ 13.2 kV is is 273 Amps. NEC table 310.78 (detail 2) permits to use 4/0 cable (90 deg C rated) up to 185 Amps for 100% loading.
Can I use two 3c4/0 cables for my application? Or should I multiply the secondary transformer currnet with 1.25 first...
