kVA Buck-Boost Transformer?

[controlnovice]

We have a new 380A/480V service with a calculated voltage drop of ~40V on the feeder. The contractor is recommending a 10kVA booster transformer on the feeder near the load.

I understand how the booster increases voltage, but I don’t understand how a 10kVA booster transformer can supply this load. I read several websites that indicate the booster transformer can supply up to 10 times its kVA rating, but how does it do this?

I’m also looking at increasing tap on main transformer and increasing cable size but would like to understand the kVA rating ‘boost’.

 

[Skogsgurra]

It is quite easy. You need a 40 V boost. Then your transformer needs a 40 V secondary to be put in series with the mains.

So, the power is 40 V times current. If the system voltage is around 400 V, it is obvious that the transformer will be about one tehth of the total power. Same goes for a three-phase installation.

Gunnar Englund

http://www.gke.org

 

[controlnovice]

Thanks!

 

[cuky2000]

Beware that during light load conditions the receiving end voltage will be higher than during full load conditions.
The voltage regulation, %V= 100 (VS — Vr) / Vr < 3 %.( typically)
_{Where:
Vs=sending end voltage at source
Vr= Receiving end voltage at load}
If an acceptable voltage regulation cannot be achieved with a regular buck-booth transformer, an automatic voltage regulator unit should be considered