Step Up Transformer Inrush Current Problem
Step Up Transformer Inrush Current Problem
(OP)
Hi Guys,
Looking for some help with a situation going on at a project now.
We are installing some new cooling equipment at an older hospital here in NYC.
The services for the hospital are currently all 208V. So the original plan from the engineer, was to tie the new transformer into an existing 2500 bolted pressure switch (boltswitch model VLB 3411 - 3 phase 4 wire bolted pressure switch.)
The transformer we are going to use is a 1000kva step up transformer, with the 208V side as the delta and the 480V side as the grounded wye.
I called bolt switch and they told they would not recommend this service for there switch, due to closing in on the inrush current from the transformer. They advised that as the switch is closing and voltage makes it to the transformer the 12x inrush could potentially fuse the switch part way closed.
My ultimate solution to this is to use a GE HPC butt contact 2500 amp switch between the boltswitch 2500 amp switch and the transformer to act almost as a "starter."
As I understood it, motor starters are butt engagement contacts to handle the inrush from the motor. So this GE switch is going to act very similarly.
If anyone has any experience with this, I would appreciate some feedback and considerations on my designs here.
Thanks,
Rob
Looking for some help with a situation going on at a project now.
We are installing some new cooling equipment at an older hospital here in NYC.
The services for the hospital are currently all 208V. So the original plan from the engineer, was to tie the new transformer into an existing 2500 bolted pressure switch (boltswitch model VLB 3411 - 3 phase 4 wire bolted pressure switch.)
The transformer we are going to use is a 1000kva step up transformer, with the 208V side as the delta and the 480V side as the grounded wye.
I called bolt switch and they told they would not recommend this service for there switch, due to closing in on the inrush current from the transformer. They advised that as the switch is closing and voltage makes it to the transformer the 12x inrush could potentially fuse the switch part way closed.
My ultimate solution to this is to use a GE HPC butt contact 2500 amp switch between the boltswitch 2500 amp switch and the transformer to act almost as a "starter."
As I understood it, motor starters are butt engagement contacts to handle the inrush from the motor. So this GE switch is going to act very similarly.
If anyone has any experience with this, I would appreciate some feedback and considerations on my designs here.
Thanks,
Rob






RE: Step Up Transformer Inrush Current Problem
RE: Step Up Transformer Inrush Current Problem
I max = 2020*height of coil*area of coil*(B residual flux+2*B max operating flux- B sat)/(N excitation turns*Effective Area)
RE: Step Up Transformer Inrush Current Problem
I would be interseted to know what is the 2020 comes from. I assume thats a simplification of some sort, but do you have a website with a derivation?
Thanks,
Rob
RE: Step Up Transformer Inrush Current Problem
RE: Step Up Transformer Inrush Current Problem