Search

Cyber Monday Deal💥

Save 20% with a coupon CYBM20 on PRO Membership Plan and 30% on courses at EEP Academy! Learn from experienced engineers!

Home / Technical Articles / Connections and working principles of three-phase distribution transformers

Three-Phase Transformers

A three-phase service can be supplied by one three-phase transformer unit or by interconnecting three single-phase transformer units. One three-phase unit is smaller than an equivalent size bank consisting of three single-phase units.

Connections and working principles of three-phase distribution transformers
Connections and working principles of three-phase distribution transformers

One three-phase transformer tends to be used in underground vaults or as a pad-mount transformer (Figure 1). An illustration of a three-phase transformer is shown in Figure 2.

One three-phase unit is easier to install because the polarity and interconnections between the phases are fixed. The use of three single-phase units is common in overhead distribution.

1000kVA 3-phase padmounted transformer
Figure 1 – 1000kVA 3-phase padmounted transformer (photo credit: newdirectionutilities.com)

When single-phase transformers are banked together, they can be interconnected to supply more than one type of service. For example, three transformers with 120/24 V secondaries can supply a 120/208, 240/416, or a 240 V three-wire service.

Fewer specialized emergency spare transformers are needed when single-phase transformers are used.

Premium Membership Required

This technical article/guide requires a Premium Membership. You can choose an annually based Plus, Pro, or Enterprise membership plan. Subscribe and enjoy studying specialized technical articles, online video courses, electrical engineering guides, and papers. With EEP’s premium membership, you get additional essence that enhances your knowledge and experience in low- medium- and high-voltage engineering fields.

Check out each plan’s benefits and choose the membership plan that works best for you or your organization.

Cyber Monday Deal💥 – Save 20% on Pro Plan and courses with code CYBM20

Log In »Purchase »

Premium Membership

Get access to premium HV/MV/LV technical articles, electrical engineering guides, research studies and much more! It helps you to shape up your technical skills in your everyday life as an electrical engineer.
More Information
author-pic

Edvard Csanyi

Electrical engineer, programmer and founder of EEP. Highly specialized for design of LV/MV switchgears and LV high power busbar trunking (<6300A) in power substations, commercial buildings and industry facilities. Professional in AutoCAD programming.

Leave a Comment

Tell us what you're thinking. We care about your opinion! Please keep in mind that comments are moderated and rel="nofollow" is in use. So, please do not use a spammy keyword or a domain as your name, or it will be deleted. Let's have a professional and meaningful conversation instead. Thanks for dropping by!

  +  eight  =  17

Learn How to Design Power Systems

Learn to design LV/MV/HV power systems through professional video courses. Lifetime access. Enjoy learning!

Subscribe to Weekly Newsletter

Subscribe to our Weekly Digest newsletter and receive free updates on new technical articles, video courses and guides (PDF).
EEP Academy Hand-Crafted Courses
ETAP technical webinars