Premium Membership ♕

CYBER MONDAY OFFER 💥 Save 20% on PRO Membership Plan and Video Courses with the coupon CYM23 and learn from experienced engineers.

Home / Technical Articles / Transformer and Transformer-Feeder Protection
VAMP transformer protection relay
VAMP transformer and feeder manager suitable for feeder and transformer applications where

The development of modern power systems has been reflected in the advances in transformer design. This has resulted in a wide range of transformers with sizes ranging from a few kVA to several hundred MVA being available for use in a wide variety of applications. The considerations for a transformer protection package vary with the application and importance of the transformer. To reduce the effects of thermal stress and electrodynamic forces, it is advisable to ensure that the protection package used minimises the time for disconnection in the event of a fault occurring within the transformer.

Small distribution transformers can be protected satisfactorily, from both technical and economic considerations, by the use of fuses or overcurrent relays.

This results in time-delayed protection due to downstream co-ordination requirements. However, time-delayed fault clearance is unacceptable on larger power transformers used in distribution, transmission and generator applications, due to system operation/stability and cost of repair/length of outage considerations.

Transformer faults are generally classified into five categories:

  1. Winding and terminal faults
  2. Core faults
  3. Tank and transformer accessory faults
  4. On–load tap changer faults
  5. Abnormal operating conditions
  6. Sustained or uncleared external faults

For faults originating in the transformer itself, the approximate proportion of faults due to each of the causes listed above is shown in Figure 1.

Figure 1 - Transformer fault statistics
Figure 1 - Transformer fault statistics

Winding Faults

A fault on a transformer winding is controlled in magnitude by the following factors:

  1. Source impedance
  2. Neutral earthing impedance
  3. Transformer leakage reactance
  4. Fault voltage
  5. Winding connection

Reference: Network protection and automation guide

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

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.

One Comment

    Feb 17, 2020

    The your portal is the best for the Learning and brush up the technical system

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!

8  ×    =  sixty four

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