11kV vs 22kV vs 33kV Transformer: How to Choose

Most industrial and commercial intake substations run at one of three voltages: 11 kV, 22 kV or 33 kV. The transformer itself looks similar in each case; the differences are in current, insulation level and the cost of everything connected to it.

This comparison will help you understand what changes when the voltage class changes.

Current halves as voltage doubles

For the same kVA, current is inversely proportional to voltage. A 2000 kVA transformer draws about 105 A at 11 kV, 52 A at 22 kV and 35 A at 33 kV.

Lower current means smaller conductors, lower I²R losses and longer possible cable runs, which is why higher voltage is used for larger loads and longer distances.

Insulation level and clearances increase

Each step up in system voltage requires a higher lightning impulse withstand level (BIL), larger creepage distances on bushings and greater internal clearances. This increases the size and cost of the transformer at a given kVA.

Switchgear and installation cost

MV switchgear, cable terminations, protection equipment and the skilled labour to install them all cost more at higher voltage. For small loads this can outweigh the cable savings of a higher voltage supply.

Typical application of each class

11 kV. Most common distribution level worldwide. Standard for factories, commercial buildings and utility distribution.

22 kV. Larger industrial sites, district distribution, longer feeders.

33 kV. Large industrial intakes, heavy process plants, primary distribution networks.

Side-by-side comparison for 2000 kVA

Rated current. 105 A at 11 kV / 52 A at 22 kV / 35 A at 33 kV

Relative cable losses. Highest at 11 kV, lowest at 33 kV

Insulation level. Lowest at 11 kV, highest at 33 kV

Switchgear cost. Lowest at 11 kV, highest at 33 kV

Frequently Asked Questions

Which voltage is best for a factory?

Whichever the utility offers for your load size. In many markets that is 11 kV up to a few MVA, and 22 kV or 33 kV above that.

Can an 11 kV transformer be upgraded to 22 kV later?

Not by re-tapping. The insulation system is built for a specific class, so upgrading means replacing the transformer.

Does higher voltage mean lower losses?

For the same power and the same conductor size, yes, lower current gives lower I²R losses in cables and windings.

Related Products, Applications and Support

Not sure which rating fits your project? Send us your load list and we will size it for you, or email info@xsdfftransformer.com, call +86 158 6789 7761 or WhatsApp +852 5416 2620.