Unit 65
Utilisation of Electrical
Energy
Assignment 1b
Power Transformer Analysis
By Ian Greene
Contents
Assignment Brief: - 3
Single-Phase Transformer 4
PolyPhase Transformer 5
Star-Star (Y-Y) Connection Mode 6
Delta-Star (∆-Y) Connection Mode 8
Delta-ZigZag (∆-Z) Connection Mode 10
Sources/References 12 Notes 13 Assignment Brief: - Describe the following connection modes for polyphase transformers; Star – Star Delta – Star Delta – Zig Zag Single-Phase Transformer A transformer is an electrical machine that is used to either step up or step down alternating voltage on a A.C supply to a higher or lower value and is essential for transmitting electricity from a power station to a home by stepping down the voltage 230v or for a phone charger as the 230V needs to be stepped down to 5V for a mobile phone A single - phase transformer consists of a single primary and secondary winding coiled around an iron or steel core. https://www.customcoils.com/theory-of-operation-of-single-phase-transformers[10/10/17] In a transformer when an alternating voltage on an A.C supply is applied to the primary winding it produces an alternating magnetic flux across the core linking and inducing a voltage into the secondary winding. The voltage induced into each winding is dependent on the number of turns such as if you increase the number of turns in the secondary winding to be greater than the primary winding it will increase the output voltage and alternatively by decreasing the number of turns in the secondary will lower the output voltage. Polyphase Transformer A polyphase transformer are used for stepping up or stepping down three-phase voltage since they consist of three sets of primary windings and secondary windings carrying alternating current that are coiled on each individual legs in pairs. It allows polyphase transformers to be useful for transmitting three-phase voltage across long distances to heavy industry. http://www.gamatronic.com/three-phase-transformers[9/10/17] There are also a number of ways a polyphase transformers since they step up or down three-phase voltage so can be connected in a number of various ways. Star-Star (Y-Y) Connection mode A Y-Y connection is a four wire, three-phase system that is wired with each phase being treated separately as single-phase system with only one pair of primary and secondary but all phases share a neutral wire. Power Transformers Principles and Applications by John J. Winders, Jr All primary and secondary windings on each leg are connected by the induced magnetic flux on the core of the transformer along with each phase on the primary and secondary side being 120° out of phase to the other other …show more content…
Winders, Jr
In a Y-Y transformer the zero-sequence magnetizing currents produced by the odd harmonics all meet neutral point producing the current that goes through the neutral going back to the voltage supply. It also stops any distortion in the secondary phase voltages as the magnetic flux in the core of the transformer has a sinusoidal waveform and since the voltages are induced by the flux it will also give a sinusoidal waveform for the voltage stopping any distortion.
Star-Star (Y-Y) Transformer without grounded neutral
Power Transformers Principles and Applications by John J. Winders, Jr
With no grounded neutral it means there is no path for the zero-sequence magnetizing currents that causes a voltage distortion in the secondary phases that also results in a higher unwanted voltage in the windings.
Delta-Star (∆-Y) Connection mode
In a ∆-Y connected transformer the input primary side is delta that is three phases all connected phase to phase without a neutral and the output secondary side is wired in star that consists of three separate phases only connected by a common grounded neutral …show more content…
https://electricalnotes.wordpress.com/2012/05/04/zig-zag-connection-of-transformer/[24/10/17]
On the zigzag when three currents all equal and are in phase is applied on the zigzag transformer the ampere turns of each winding all cancel the ampere turns of each other which allows the in phase currents to flow to the neutral connected to all three phases. If the same is applied but the currents are 120° out of phase with each other then current isn’t allowed to flow since the windings haven’t canceled each other out.
A ∆-Z provides both third harmonic suppression and ground current isolation since it incorporates features from ∆-Y transformer but it also provides a bonus that the others don’t that is there is no phase angle displacement between the primary input and secondary
Utilisation of Electrical
Energy
Assignment 1b
Power Transformer Analysis
By Ian Greene
Contents
Assignment Brief: - 3
Single-Phase Transformer 4
PolyPhase Transformer 5
Star-Star (Y-Y) Connection Mode 6
Delta-Star (∆-Y) Connection Mode 8
Delta-ZigZag (∆-Z) Connection Mode 10
Sources/References 12 Notes 13 Assignment Brief: - Describe the following connection modes for polyphase transformers; Star – Star Delta – Star Delta – Zig Zag Single-Phase Transformer A transformer is an electrical machine that is used to either step up or step down alternating voltage on a A.C supply to a higher or lower value and is essential for transmitting electricity from a power station to a home by stepping down the voltage 230v or for a phone charger as the 230V needs to be stepped down to 5V for a mobile phone A single - phase transformer consists of a single primary and secondary winding coiled around an iron or steel core. https://www.customcoils.com/theory-of-operation-of-single-phase-transformers[10/10/17] In a transformer when an alternating voltage on an A.C supply is applied to the primary winding it produces an alternating magnetic flux across the core linking and inducing a voltage into the secondary winding. The voltage induced into each winding is dependent on the number of turns such as if you increase the number of turns in the secondary winding to be greater than the primary winding it will increase the output voltage and alternatively by decreasing the number of turns in the secondary will lower the output voltage. Polyphase Transformer A polyphase transformer are used for stepping up or stepping down three-phase voltage since they consist of three sets of primary windings and secondary windings carrying alternating current that are coiled on each individual legs in pairs. It allows polyphase transformers to be useful for transmitting three-phase voltage across long distances to heavy industry. http://www.gamatronic.com/three-phase-transformers[9/10/17] There are also a number of ways a polyphase transformers since they step up or down three-phase voltage so can be connected in a number of various ways. Star-Star (Y-Y) Connection mode A Y-Y connection is a four wire, three-phase system that is wired with each phase being treated separately as single-phase system with only one pair of primary and secondary but all phases share a neutral wire. Power Transformers Principles and Applications by John J. Winders, Jr All primary and secondary windings on each leg are connected by the induced magnetic flux on the core of the transformer along with each phase on the primary and secondary side being 120° out of phase to the other other …show more content…
Winders, Jr
In a Y-Y transformer the zero-sequence magnetizing currents produced by the odd harmonics all meet neutral point producing the current that goes through the neutral going back to the voltage supply. It also stops any distortion in the secondary phase voltages as the magnetic flux in the core of the transformer has a sinusoidal waveform and since the voltages are induced by the flux it will also give a sinusoidal waveform for the voltage stopping any distortion.
Star-Star (Y-Y) Transformer without grounded neutral
Power Transformers Principles and Applications by John J. Winders, Jr
With no grounded neutral it means there is no path for the zero-sequence magnetizing currents that causes a voltage distortion in the secondary phases that also results in a higher unwanted voltage in the windings.
Delta-Star (∆-Y) Connection mode
In a ∆-Y connected transformer the input primary side is delta that is three phases all connected phase to phase without a neutral and the output secondary side is wired in star that consists of three separate phases only connected by a common grounded neutral …show more content…
https://electricalnotes.wordpress.com/2012/05/04/zig-zag-connection-of-transformer/[24/10/17]
On the zigzag when three currents all equal and are in phase is applied on the zigzag transformer the ampere turns of each winding all cancel the ampere turns of each other which allows the in phase currents to flow to the neutral connected to all three phases. If the same is applied but the currents are 120° out of phase with each other then current isn’t allowed to flow since the windings haven’t canceled each other out.
A ∆-Z provides both third harmonic suppression and ground current isolation since it incorporates features from ∆-Y transformer but it also provides a bonus that the others don’t that is there is no phase angle displacement between the primary input and secondary