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Chapter 3 Transformer
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
PIN
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
Three phase transformer’s Winding
connection
Three phase transformer’s primary and secondary windings basically have four types of connection and these are:
1. Star - star:
• This is the most economical connection for small, high voltage transformers, as the number of turns per phase and the amount ofinsulation is minimum.
• The possibility of utilizing both star pints for a fourth wire may be useful. Third harmonics is absent from the line voltage; unless there is a fourth wire, no third-harmonic current will flow.
• If the transformer is worked at the normal flux density, however, the neutral potential will oscillate, while the third-harmonic phase voltage may be high for shell type three phase units.
• The connection is almost satisfactory with the three-phase core type while for other types, the provision of a tertiary winding stabilizes the neutral conditions.
Contd.2. Delta – delta:
• This is an economical connection for large, low-voltage transformers in which insulation is not a problem cause
• This connection increases the number of turns per phase and reduces the necessary sectional area of conductors.
• In delta-delta connection, large unbalance of load can be met without difficulty; the closed mesh will damp out third-harmonic voltages. Also, should one of the phases develop a fault,
• it is possible to operate the transformer at 58 % of its rating in delta connection.
• In the contrary, the absences of a star- point may be disadvantageous.
Contd.
3. Star - delta: • The star/delta arrangement is very common for
power supply transformers. • It has the advantage of a star-point for mixed
loading, and delta winding to carry third harmonic currents, which stabilizes the star-point potential.
• If the H.V. winding is the star-connected side, there is some saving in cost of insulation.
• A delta-connected H.V. winding is almost universal.
Contd.
4. Delta-star:
• In this connection, there is a reduction in the third harmonic voltage and at the same time unbalanced loading is permitted;
• on account to the type of connection, however, the delta has to be confined to a fairly low voltage winding.
• The delta/star connection has been employed where delta connections were mechanically weak (because of large number of turns and small copper sections) in high voltage transformers
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
By Sintayehu Challa
