Transformer connection
Transformer basic concept
A transformer is
static (or stationary) piece of apparatus by means of which electric power in
one circuit is transformed into electric power of the same frequency in another
circuit. It can raise or lower the voltage in a circuit but with a corresponding
decrease or increase in current. The physical basis of a transformer is mutual
induction between two circuit linked by a common magnetic flux.
·
In
its simplest from, it consist of two inductive coils which are electrically
separated but magnetically linked through a path of low reluctance.
Transformer types
·
Single
phase transformer
·
Three
phase transformer
The different types of transformer are Step up
and Step down Transformer, Power Transformer, Distribution Transformer, Instrument transformer comprising
current and Potential Transformer, Single phase and
Three phase transformer, Auto transformer, etc.
Transformer connection types
- ·
Star
connection
- ·
Delta
connection
- ·
Zig - zag
connection
Star connection
- In STAR connection, the starting or finishing ends (Similar ends) of three phases (coils) are connected together to form the neutral point. A common wire is taken out from the neutral point which is called Neutral. There is no such connection in Delta network. The Line voltage is root three times the phase voltage
Usually, Star Connection is used in both transmission and distribution networks single phase supply or three – phase. Delta Connection is generally used in
distribution networks. Since insulation required is less, Star Connection can be used for long distances.
Delta connection
In a standard delta–wye (or wye–delta) transformer, the
positive-sequence currents and voltages on the high voltage side lead the
positive-sequence currents and voltages on the low voltage side by 30°. When
the high voltage phasors lag the low voltage phasors, the connection is
considered to be non-standard.
Delta-star connected transformers are widely used in low power
distribution with the primary windings providing a three-wire balanced load to
the utility company while the secondary windings provide the required 4th-wire
neutral or earth connection.
Zig-zag connection
A zigzag transformer is used to reduce harmonics on the secondary supply. A zigzag transformer is a special-purpose transformer with a zigzag or
"interconnected star" winding connection, such that each output is
the vector sum of two (2) phases offset by 120°.
A delta-wye transformer is a type of
three-phase electric power transformer design that
employs delta-connected windings on
its primary and wye/star connected windings on
its secondary. A neutral wire can be provided on wye output side. An equivalent
term is delta-star transformer.
