Center Tapped Delta

[joan271273]

I know that this type of system was used in the past to supply electrical power to office spaces. With the new layout of offices that include the presence of Linear and Non Linear loads . What would be the impacts for tenants moving into a space with a Center Tapped Delta system as a source.

What happen if they have UPS systems, etc. [sig][/sig]

 

[jbartos]

Delta-Y transformer connection is more frequent and more standard. The center-tapped delta will have harmonic currents circulating in the delta winding, which will affect the voltage wave-forms.
The UPS may work fine, it depends how it is connected, e.g. diesel generator set, stationary battery and inverter, etc. bypassing the center-tapped delta transformer. If not, the above mentioned phenomenon will stay. [sig][/sig]

 

[jhalm]

In the best of conditions with linear loads , most manufacturers of 3-phase transformers (both dry & liquid-filled) recommend limiting single phase load on the single-phase leg to only 5% of the total xfmr kva due to circulating currents and additinal xfmr heating. This really minimizes practical use of this arrangement. When you throw lots of non-linear loading into that too, the de-rating on top of de-rating tends to make it pretty useless. One suggestion is to add a single-phase "K" rated transformer to feed only your existing single phase loads. Feed the single-primary from your existing system. This likely would have the least detrimental impact on your system. Most manufacturers of transformers have additional application notes on the subject of 4-Wire delta transformers and single phase loads.