Search

Premium Membership ♕

Limited Time Offer: Save 15% on PRO Plan with discount code: LRN15 and study specialized LV/MV/HV technical articles and studies.

Home / Download Center / Electrical Engineering Books and Technical Guides / Relay control and protection guides / Guide through applications for SIPROTEC protection relays

Protection of a three-winding transformer

Transformers are valuable equipment which make a major contribution to the supply security of a power system. Optimum design of the transformer protection ensures that any faults that may occur are cleared quickly and possible consequential damage is minimized.

Guide through applications for SIPROTEC protection relays
Guide through applications for SIPROTEC protection relays (photo credit: digitalsubstation.com)

In addition to design notes, a complete setting example with SIPROTEC protection relays for a three-winding transformer in the transmission system is described.


Protection concept

The range of high voltage transformers comprises small distribution system transformers (from 100 kVA) up to large transformers of several hundred MVA.

Differential protection offers fast, selective short-circuit protection, alone or as a supplement to Buchholz protection. It is part of the standard equipment in larger units from about 5 MVA.

Differential protection

Transformer differential protection contains a number of additional functions (matching to transformation ratio and vector group, restraint against inrush currents and overexcitation).

Therefore it requires some fundamental consideration for configuration and selection of the setting values.

SIPROTECT transformer protection relay
Figure 1 – SIPROTECT transformer protection relay

The additional functions integrated per relay are advantageous.

However, backup protection functions have to be arranged in separate hardware (other relay) for redundancy reasons. Therefore the overcurrent-time protection contained in the differential protection relay 7UT613 can only be used as backup protection against external faults in the connected power system.

The backup protection for the transformer itself must be provided as a separate overcurrent relay (e.g. 7SJ602). The Buchholz protection as fast short circuit protection is delivered with the transformer.

Designations in accordance with ANSI (American National Standard) are used for the individual functions. The differential protection therefore has the ANSI No. 87 for example.

Protection scheme of a three-winding transformer
Figure 2 – Protection scheme of a three-winding transformer

The 7UT613 differential protection relay is provided as independent, fast-acting short-circuit protection in addition to the Buchholz protection.

Title:Complete guide to applications for SIPROTEC protection relays – SIEMENS
Format:PDF
Size:13.1 MB
Pages:228
Download:Right here | Video Courses | Membership | Download Updates
Guide through applications for SIPROTEC protection relays
Guide through applications for SIPROTEC protection relays by SIEMENS

Premium Membership

Get access to premium HV/MV/LV technical articles, advanced electrical engineering guides, papers, and much more! It will help you to shape up your technical skills in your everyday life as an electrical engineer.
50% Discount 💥 - Save 50% on all 90+ video courses with Enterprise Membership plan.

More Information

One Comment


  1. Anne Kariuki
    Jan 26, 2021

    what is the password for 7sj602…I need to program to be able to test the relays overcurrent and earth fault protection

Leave a Reply to Anne Kariuki

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!

35  −  twenty seven  =  

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 Courses - A hand crafted cutting-edge electrical engineering knowledge