13.8kV - 120/240V Trailer Single Phase Service
13.8kV - 120/240V Trailer Single Phase Service
(OP)
I need to power 16 double-wide trailers, each at 120/240V and each double-wide having 2-100A single phase panels. I have a 13.8kV supply. I am thinking of a 3-phase 13.8kV-480/277V dry type Xfmr and then split up phases to feed three single phase 480-120/240V Xfmrs. However, I believe that if system is not well balanced, I run the risk of dumping the main 480V Xfmr. Practically speaking, am I going against convention or do you think there may be a better way? Appreciate your comments.






RE: 13.8kV - 120/240V Trailer Single Phase Service
But I'm curious as to why you want to drop down to 480V first? You can easily go from 13.8 kV directly to 120/240V using some small pad-mounted transformers.
RE: 13.8kV - 120/240V Trailer Single Phase Service
RE: 13.8kV - 120/240V Trailer Single Phase Service
Depending on secondary-circuit distances, going 13.8kV – 208Y/120 may be an option. One gotcha is that trailer ‘wall-pack’ air conditioning be intended for 208 and not only 240V service.
RE: 13.8kV - 120/240V Trailer Single Phase Service
How are you going to want to meter this? By individual space?
RE: 13.8kV - 120/240V Trailer Single Phase Service
RE: 13.8kV - 120/240V Trailer Single Phase Service
I need to power 16 double-wide trailers, each at 120/240V and each double-wide having 2-100A single phase panels. I have a 13.8kV supply. I am thinking of a 3-phase 13.8kV-480/277V dry type Xfmr
///Have you estimated kVA size of this transformer? What about a type, a pad mounted or mobile?\\\
and then split up phases
///In large junction box? Or daisy chain the single phase transformers in three chains? This will depend on a location of the 13.8kV-480/277V dry type Xfmr.\\\
to feed three single phase 480-120/240V Xfmrs. However, I believe that if system is not well balanced, I run the risk of dumping the main 480V Xfmr.
///Considering 16 trailers, 100A services, the 480V secondary transformer can reasonably be balanced. Even, if some imbalance exists, it will be unavoidable or tolerable considering the kVA size of the 480V transformer. The electrical contractor check the load of each of 16 trailers and balance the 480V power distribution.\\\
Practically speaking, am I going against convention or do you think there may be a better way?
///There may be some marginal savings, depending on locations of the trailers. Also, two 13.8kV-480V transformers may be considered to provide redundancy of power supply to 16 trailers, with essentially 8 trailers on each transformer and provisions to power 8 trailers from the other transformer.\\\
RE: 13.8kV - 120/240V Trailer Single Phase Service
1. Have you estimated kVA size of this transformer? What about a type, a pad mounted or mobile? ///Initially, I had envisioned a 3-phase, 1500 kVA, 13.8 kV – 480/277V dry type pad mounted-Y having 1804 amps on secondary. This would then feed three 1-phase 250kVA, 480-120/240 with 521A on primary each to yield 1042 amps on secondary of each. This would in turn feed, roughly, 5-double wides (5x200A=1000A), as each double wide would need 200 amps (2-100A panels.)\\\
2. In large junction box? Or daisy chain the single phase transformers in three chains? This will depend on a location of the 13.8kV-480/277V dry type Xfmr. ///13.8 kV would feed down the pole to the 3-phase Xfmr, to JB to the 3-1Phase Xfmrs all in close proximity. All trailers would also be right close to each other in a cluster, not too far from power source\\\
3. Considering 16 trailers, 100A services, the 480V secondary transformer can reasonably be balanced. Even, if some imbalance exists, it will be unavoidable or tolerable considering the kVA size of the 480V transformer. The electrical contractor check the load of each of 16 trailers and balance the 480V power distribution. ///Correct, adjustments would be made before final service.\\\
4. There may be some marginal savings, depending on locations of the trailers. Also, two 13.8kV-480V transformers may be considered to provide redundancy of power supply to 16 trailers, with essentially 8 trailers on each transformer and provisions to power 8 trailers from the other transformer.///Thank you, redundancy is now a consideration.\\\
RE: 13.8kV - 120/240V Trailer Single Phase Service
The 1500kVA transformer for 16 trailers seems to have a big kVA margin. Are there big motor loads in the trailers? Or are you anticipating a load growth (additional trailers)?
1500kVA/(16 trailers x .240V)=391A/trailer versus 200A panel/trailer.
RE: 13.8kV - 120/240V Trailer Single Phase Service
RE: 13.8kV - 120/240V Trailer Single Phase Service
Also, the pole mounted transformers are more convenient for permanent installations. The mobile transformer solution is more convenient for a temporary power distribution.
RE: 13.8kV - 120/240V Trailer Single Phase Service