FEE Flashcards - Transformers
refers to one of the individual alternating current waveforms in a polyphase system.
Phase
an electrical system that uses multiple alternating currents, each with a unique phase angle.
Polyphase System
This system allows efficient generation, transmission, and utilization of power, reducing energy losses compared to single-phase systems.
Polyphase System
The most common configuration of polyphase system
three-phase system
a type of polyphase system where three AC currents are generated with identical magnitudes and frequencies but are separated by 120° phase angles.
three-phase system
angular displacement between two sinusoidal waveforms of the same frequency
Phase Angle
voltage measured between any two line conductors in a polyphase system.
Line Voltage
Formula for Line Voltage
Vl = Vphase√3
voltage measured across a single phase of the load or generator.
Phase Voltage
In a star-connected system, it is the voltage between a phase conductor and the neutral point.
Phase Voltage
one in which all the phase voltages or currents have equal magnitudes and are separated by equal phase angles.
Balanced System
ensure efficient power transfer and reduce the risk of overheating in transmission lines or equipment.
Balanced System
occurs when the magnitudes of the phase voltages or currents are not equal, or their phase angles deviate from the ideal values.
Unbalanced System
a connection where one end of each phase winding is connected to a common neutral point
Star Connection
It is widely used in power distribution.
Star Connection
This connection allows the use of a neutral wire for grounding and provides multiple voltage levels
Star Connection
A connection where the phase windings are connected end- to-end in a closed loop,
Delta Connection
This configuration eliminates the need for a neutral wire and is common in industrial motor applications due to its ability to handle high currents and power.
Delta Connection
the current flowing through a line conductor in a polyphase system.
Line Current
Line Current Formula
Il = iphase√3
the current flowing through a single phase of a load or generator.
Phase Current
Its magnitude depends on the load and the system’s connection type (star or delta).
Phase Current
a conductor in a star-connected system that provides a return path for current and helps stabilize voltage levels.
Neutral Wire
It is particularly important in handling unbalanced loads.
Neutral Wire
a static electrical device that transfers electrical energy between two or more circuits through electromagnetic induction.
Transformer
It operates on the principle of Faraday’s law of electromagnetic induction
Transformer
states that a time-varying magnetic field induces an electromotive force (EMF) in a conductor.
Faraday’s law of electromagnetic induction
___ of a transformer is connected to the input (supply) side.
Primary winding
When an alternating current flows through it, a magnetic field is created in the transformer core.
Primary winding
connected to the output side of the transformer.
Secondary Winding
The voltage induced in this winding is transferred to the load.
Secondary Winding
the ratio of the number of turns in the primary winding to the number of turns in the secondary winding
Turns Ratio
It determines the relationship between the input (primary) and output (secondary) voltages
Turns Ratio
Turns Ratio Formula
Turns Ratio = Np/Ns = Vs/Vp
a transformer that increases voltage from primary to secondary
Step-Up Transformer
It has more turns in the secondary winding than the primary winding.
Step-Up Transformer
a transformer that decreases voltage from primary to secondary
Step-Down Transformer
It has fewer turns in the secondary winding than the primary winding.
Step-Down Transformer
part of the transformer that provides a low-reluctance path for the magnetic flux.
Core (magnetic Core)
The Core of a transformer is typically made of ___ to minimize energy losses due to eddy currents.
laminated silicon steel
thin layers of steel used in the transformer core to reduce eddy current losses.
Laminations
The ___ are insulated from each other to prevent circulating currents.
Lamination
Special Types of Transformers
Auto-, Isolation, Three-phase, Current, Potential, and Toroidal Transformer
a transformer with a single winding that acts as both the primary and secondary.
Auto-Transformer
a transformer designed to isolate two circuits electrically while maintaining power transfer.
Isolation Transformer
It has a 1:1 turns ratio and is often used for safety and noise reduction.
Isolation Transformer
a transformer designed for three-phase power systems.
three-phase transformer
It can consist of three separate single-phase transformers or a single unit with three sets of windings.
Three-phase transformer
a type of transformer used to measure current.
Current Transformer
It reduces high currents in power systems to a smaller, more manageable level for meters and relays.
Current Transformer
a transformer used to measure voltage by stepping down high voltages to a lower level suitable for meters and relays.
Potential Transformer
a transformer with a donut- shaped core that offers high efficiency and reduced electromagnetic interference (EMI).
Toroidal Transformer
