A percentage differential protection scheme is to be designed for a Delta-Star connected, 20 MVA,22/0.4 kV distribution transformer. The capacity of this transformer to handle the overload can beassumed in the range of 20-35%. The CTs to be used for sensing currents in the primary as wellas secondary side of the transformer are available with 1A OR 5A rating.(i)Choose appropriate ratios for the CTs to be used in the protection scheme.QEAD Template ARey: 04 ver 02Date0f'October 2018Paget of3F/QAP/021/001(ii)Determine pilot wire currents on primary as well as secondary side.(i)Identify whether interposing CTs are necessary. If they are necessary, outline theirspecifications and exact location.(iv)Sketch the complete protection scheme showing primary/secondary windings for thetransformer, CTs used on primary/secondary sides and exact position of interposingCTs;(v)For the differential relay of 40% setting, determine whether the relay will operate at35% overload condition.(vi)Investigate if the interposing CTs will be necessary iftransformer connections arechanged to Star-Star instead of Delta-Star.

Answered: Image /qna-images/answer/66cd5d40-ae9c-482e-8edc-bc3727df1046.jpg

A percentage differential protection scheme is to be designed for a Delta-Star connected, 20 MVA, 22/0.4 kV distribution transformer. The capacity of this transformer to handle the overload can be assumed in the range of 20-35%. The CTs to be used for sensing currents in the primary as well as secondary side of the transformer are available with 1A OR 5A rating. (i) Choose appropriate ratios for the CTs to be used in the protection scheme. QEAD Template A Rev: 04 ver 02 DateDf October 2018 Paget of3 F/QAP/021/001 (ii) Determine pilot wire currents on primary as well as secondary side. (ii) Identify whether interposing CTs are necessary. If they are necessary, outline their specifications and exact location.

A percentage differential protection scheme is to be designed for a Delta-Star connected, 20 MVA, 22/0.4 kV distribution transformer. The capacity of this transformer to handle the overload can be assumed in the range of 20-35%. The CTs to be used for sensing currents in the primary as well as secondary side of the transformer are available with 1A OR 5A rating. (i) Choose appropriate ratios for the CTs to be used in the protection scheme. QEAD Template A Rev: 04 ver 02 DateDf October 2018 Paget of3 F/QAP/021/001 (ii) Determine pilot wire currents on primary as well as secondary side. (ii) Identify whether interposing CTs are necessary. If they are necessary, outline their specifications and exact location.

Power System Analysis and Design (MindTap Course List)

6th Edition

ISBN:9781305632134

Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Publisher:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Chapter3: Power Transformers

Section: Chapter Questions

Problem 3.9P

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do the iv) part with figure A percentage differential protection scheme is to be designed for a Delta-Star connected, 20 MVA, 22/0.4 kV distribution transformer. The capacity of this transformer to handle the overload can be assumed in the range of 20-35%. The CTs to be used for sensing currents in the primary as well as secondary side of the transformer are available with 1A OR 5A rating. Choose appropriate ratios for the CTs to be used in the protection scheme. (ii) Determine pilot wire currents on primary as well as secondary side. (iii) Identify whether interposing CTs are necessary. If they are necessary, outline their specifications and exact location. (iv) Sketch the complete protection scheme showing primary/secondary windings for the transformer, CTs used on primary/secondary sides and exact position of interposing CTs; (v) For the differential relay of 40% setting, determine whether the relay will operate at 35% overload condition. (vi) Investigate if the interposing CTs will…
Please explain each step
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solve with explanation.