Good point Bill. It would be mostly resistive load.
I'm curious how far (how tall of a building) increased cable size would get you before it is no longer cost effective, versus installing additional transformers on multiple floors. Also, could you have the customer install step-transformers...
These are helpful. Thanks.
Has anyone heard of using capacitors to raise voltages in this scenario? I'm thinking of leveraging AMI meter data to monitor voltage, and using controlled capacitors on the secondary voltage side to raise secondary voltage as needed when the loads are high. Then we...
Our city skyline is getting taller. So much so that the new taller high-rises are limited by voltage drop. We are having this issue on our Network system, where we typically service customers from the ground floor with either 480V or 208V. We considered running primary up the building and...
We're trying to phase out the open delta banks, so when an open-delta transformer fails the linemen are replacing them with 480V wye banks and not running the neutral. However, we're told this is a safety issue and could burn up the customers' equipment.
We have some 2-bushing 277/480V overhead transformers in stock and would like to use them to install a 480V open delta bank (versus using 3-bushing transformers that have a center tap, which we don't have in stock). I'm not a transformer connection expert, but I'm thinking I can delta-connect...
My utility started using a #2 Stranded Copper for their loop ground on overhead distribution transformers (versus #6 solid copper previously). I can't figure out the reasoning to this. For a 167kVA 120V transformer the fault current is max 57,300 amps. With this size fault current the...
In trying to determing the ratings of underground cable for my company I determined that the manufacturers vary widely in their ratings, i.e., for 25kV 4/0 Copper 1/3 neutral 260 Mil insulated cable buried in ducts: Southwire = 287 Amps, King Wire = 320 Amps, and Perreli = 314 Amps. The ratings...
Thanks resqcapt. Seems like the NEC is supporting putting all phases in one conduit if using metal conduit.
I'm thinking of going to a high scheduled pvc, though, instead of putting all the phases in one conduit. That way if we fault a phase we won't loose all three.
We use a stranded concentric neutral that comes on the parameters of the urd cable.
Sounds logical in theory, but I still haven't found any documentation on the subject and haven't experienced it on any of our metal conduit.
None yet. However, we keep hearing that same comment everytime we mention our method of one phase per metal conduit. However, no one seems to know any details about the specifics of why it is a problem, i.e., what happens electrically, how much load before it becomes a problem, will shielded...
I've heard talk that pulling urd cable into metal conduit with one phase per conduit is a bad idea due to induction. We currently do so at our risers and then the cable runs into pvc conduit underground.
Does anyone know where I can find documentation on this subject or can explain to me the...
Update: I asked around at some of our surrounding utilities that use the same transformers we use. We seem to be the only utility having multiple xfmr failure due to lightning. The only difference I could determine was our connection. All the utilities I called make the connection that Cooky...
Transformer splitting meaning the case split open. We've had over 12 react the same way this year. I'd say it's time to change our connection.
Thanks for your help.
Isn't the idea to have the arrester drain the surge before it hits the bushing? Seems like you would be accomplishing that by Tinfoil's design. The impedance should be lower through the pole ground than through transformer.
