Thank you. Your comment has led me down a rabbit hole of trying to figure out if we are going to be okay due to this. The Aspen model says yes but Easypower model is saying maybe.
Sounds like another good way to reduce the fault current. It would also be subject to the ISO's review of the overall impedance change of the system just like changing the transformer impedance. We are also dealing with a limited footprint for the stie so I'm not sure we would have the space...
From reviewing some responses on other threads from forum user PRC and also reviewing some modeling data I have access to, it appears that the impedance between two secondary windings of a 3 winding transformer is roughly 0.95 the summation of the impedances between the primary and each of the...
I'm reviewing a project where there is a 270MVA 161/34.5kv transformer and no main circuit breaker on the 34.5kv bus. (I don't know of any circuit breaker for 34.5kv that is higher than 3000A which is a force air cooled switchgear breaker)
The 34.5kv bus has (8) 600A breakers. (7) of the...
I believe the ISO would accept a difference of the total impedance of 10% or less from the originally studied transformer. We would have to develop the transformer spec. to match it as best as possible.
We have a 325MW renewable site that was studied with a Y-g 345kv / Delta 34.5kv 350MVA two winding transformer but we are kicking around the idea of changing it to a three winding transformer to reduce the secondary current. If we kept the impedance the same between the primary and the two...
Thank you. I recently read that shell type transformers are more energy efficient and have better fault duties thus more likely to be specified. I have no real world data points on this so I was wondering if you had any insight that could be shared?
From reading the excerpt below from IEC 60076-8, I'm interpreting Z0 to be .85-0.9 the value of Z1. Is this a correct interpretation? I've recently seen utilities/ISOs requesting Z0 data on transformer during the interconnection studies and I can't seem to get a good understanding on this...
I was searching for OLTC topics as I'm currently looking at a inverter based project where we didn't show an OLTC but the client insists that they want it. From speaking to a few people at work, and from what wcaseyharman said above, it sounds like the inverters should be able to handle the...
Has anyone ever seen a 345kv GIS underground connection where two sets of conductors are paralleled into the same position? I believe this can be done with AIS equipment based on my review of some substations in NYC but didn't know if it was possible with GIS. I have the question going into...
Yes, just made contact at NKT which I believe took over ABB's cable business. That Bayonne project was the only 345kv project that I could find when I had done some previous searches, it doesn't seem like there is much of a market for cable manufactures to go after.
Anyone ever seen these before? I've only seen up to 275kV systems. What I'm trying to figure out is how far could a 345kv submarine cable go without charging current being a problem. *Edit: The system size is 1200MW
Agreed that 150MW at 0.95pf capability at the POI would limit things. I've seen 4000A bus at 115kv so I'm not sure why we couldn't have 4000A at 34.5kv to parallel into a single MPT. I'm assuming we could get the transformer differential protection to work between a high side breaker and two...
I've been looking into this a bit and it seems like the highest ampacity of readily available equipment you can get for 34.5kv is 3000A. I'm looking at a collector substation for a renewable projects where they are trying to produce 200MW and I'm wondering if there are alternative solutions to...
Thanks for sharing that link, lots of good info in there to read up on! I was able to get some data points for similar sized 345/34.5 utility transformers and the impedance ranged between 9-12.5% and X/R ranged between 40-49
Sorry to start another one of these threads but I've gone through some of the old threads where Cuky2000 has responded and have a few questions. For a 345kv/34.5kv transformer is there a reasonable way to estimate the impedance and X/R? I've been looking at the Cuky2000 table named "Standard...
Thanks for the heads up on induced currents. Yes we will be using to verify they are below the NY state required levels.
Some example projects that are in the process of being submitted can be found at the link below. Each submission should have an Appendix 22 for the EMF study...
We are using it to measure the field strength for 34.5kv circuits along roadways for a PV project. We are planning on picking up the magnetic field module with CYMCAP so it sounds like we should be okay with that software package.
