Which of the following connections in a three-phase transformer is called open-delta connection?

This question was previously asked in
SSC JE EE Previous Paper 11 (Held on: 24 March 2021 Morning)
View all SSC JE EE Papers >
  1. V-V
  2. Δ-Δ
  3. Δ-Y
  4. Y-Y

Answer (Detailed Solution Below)

Option 1 : V-V
Free
Electrical Machine for All AE/JE EE Exams Mock Test
20 Qs. 20 Marks 20 Mins

Detailed Solution

Download Solution PDF

Open-delta connection:

  • An open delta connection transformer uses two single-phase transformers to provide a three-phase supply to the load.
  • An open delta connection system is also called a V-V system.
  • Open delta connection systems are usually only used in emergency conditions when one of the transformers in the Delta-Delta system is damaged, and removed from service.    
  • Efficiency for the operation of open delta connection is low as compared to delta-delta systems which are used during standard operations.


Power supplied by open delta connection

Power supplied by open delta connection

Therefore, 

Hence, the total load supplied by the open delta system is 57.77% of the closed delta system.

Latest SSC JE EE Updates

Last updated on Jul 1, 2025

-> SSC JE Electrical 2025 Notification is released on June 30 for the post of Junior Engineer Electrical, Civil & Mechanical.

-> There are a total 1340 No of vacancies have been announced. Categtory wise vacancy distribution will be announced later.

-> Applicants can fill out the SSC JE application form 2025 for Electrical Engineering from June 30 to July 21.

-> SSC JE EE 2025 paper 1 exam will be conducted from October 27 to 31. 

-> Candidates with a degree/diploma in engineering are eligible for this post.

-> The selection process includes Paper I and Paper II online exams, followed by document verification.

-> Prepare for the exam using SSC JE EE Previous Year Papers.

Hot Links: teen patti master new version teen patti yas teen patti - 3patti cards game downloadable content teen patti master purana