mbrooke
Batteries Included
- Location
- United States
- Occupation
- Technician
What is the largest 120/208 volt Y service you've ever encountered in your career?
What is the largest 120/208 volt Y service you've ever encountered in your career?
Common here is 400/230V Y as nominal voltage LV distribution. Typically they are around 1.5MVA.
What is the perspective fault current on something like that?
Our current project has 4-4000 amp services at 208Y/120 volts. That's the largest I've ever installed at that voltage. If I remember correctly years ago we had a 5000 amp service at 480Y/277 volts.
Our current project has 4-4000 amp services at 208Y/120 volts. That's the largest I've ever installed at that voltage. If I remember correctly years ago we had a 5000 amp service at 480Y/277 volts.
I’m curious about this.... what type of facility is it? I’m guessing it had to be more cost effective to purchase the transformers from the utility and have them install.
Sent from my iPhone using Tapatalk
I’m curious about this.... what type of facility is it? I’m guessing it had to be more cost effective to purchase the transformers from the utility and have them install.
What type of facility? How many POCO transformers? How many stories?
Apartment complex, two towers, one 26 stories the other 40 stories. About 720 units with a large amenities space. Not sure why they went with a 208Y/120 volt services typically these would be 480Y/277. Could be they didn't want to put in a 480 volt network system which requires space within the building. So we now have about a dozen step-up substations in the service room of the building, some 480 volts some 4160. The 4160 is stepped down to 208Y/120 for apartment power as it goes up the building.
Apartment complex, two towers, one 26 stories the other 40 stories. About 720 units with a large amenities space. Not sure why they went with a 208Y/120 volt services typically these would be 480Y/277. Could be they didn't want to put in a 480 volt network system which requires space within the building. So we now have about a dozen step-up substations in the service room of the building, some 480 volts some 4160. The 4160 is stepped down to 208Y/120 for apartment power as it goes up the building.
Apartment complex, two towers, one 26 stories the other 40 stories. About 720 units with a large amenities space. Not sure why they went with a 208Y/120 volt services typically these would be 480Y/277. Could be they didn't want to put in a 480 volt network system which requires space within the building. So we now have about a dozen step-up substations in the service room of the building, some 480 volts some 4160. The 4160 is stepped down to 208Y/120 for apartment power as it goes up the building.
That sounds like a fun project; I have zero experience with buildings of that size. Is the 480 for HVAC and common area/exterior lighting?
I might have done it the same way. If 208 makes the bulk of the load it makes sense IMO. Hate to see a 225kva step down on every floor.
Yes the 480Y/277 is for the chillers, HVAC, elevators, fans, pumps, etc.
IMO the flaw is that instead of that (208 volt vertical risers) we have 4160 step-up and 4160-208Y/120 step down transformers for the apartment power anyway. All of the 480 is derived from huge transformers as well. It is nice to run a single 2.5" riser the height of the building and end up with 1000 amps at 208Y/120 on the other end. :thumbsup:
208 Volt, 3 phase, 4000-amp at a hospital in Brooklyn, NY. And it was probably 50+ years old. The reported fault current was 200kA. There were five 1000 kVA transformers network-connected on the other side of the wall in the basement of the facility.
I was doing data collection for an arc flash study and couldn't 't find the current-limiting fuses that were shown on the drawings. So I took 40 nuts off the cover off a 3' by 4' protruding enclosure. The cover was held by 4 captive studs. When I popped the cover off to inspect it, I found the 4000-amp, 208 Volt busbar was about 3/4' from the face of the cover. It scared the bejeezus out of me, but it made sense. There wasn't the need for much clearance because it was just 208 Volts.