AC-AC Transformers Flashcards
What do AC-AC transformers do?
AC-AC transformers transfer electrical energy between circuits, changing voltage and current levels while isolating circuits.
How do transformers work?
They operate on the principle of electromagnetic induction, transferring energy between primary and secondary windings through a magnetic core.
What are the main types of transformers?
Step-up, step-down, isolation, autotransformers, and current transformers.
What is a step-up transformer?
A transformer that increases voltage from the primary to the secondary winding.
What is a step-down transformer?
A transformer that decreases voltage from the primary to the secondary winding.
What is an isolation transformer?
A transformer with a 1:1 turns ratio used to electrically isolate two circuits.
What is an autotransformer?
A transformer with a single winding that acts as both primary and secondary, sharing part of the winding.
What is a current transformer (CT)?
A transformer used to measure current in high-power circuits by producing a proportional lower current.
What is the turns ratio in a transformer?
The ratio of the number of turns in the primary winding to the number of turns in the secondary winding.
How do you calculate the voltage ratio of a transformer?
Vsecondary/Vprimary = Nsecondary/Nprimary
Where N is the number of turns.
What is the efficiency of a transformer?
The ratio of output power to input power, typically expressed as a percentage.
What is the purpose of the core in a transformer?
To provide a path for the magnetic flux, improving efficiency and reducing losses.
What materials are used for transformer cores?
Laminated iron, ferrite, or powered iron, depending on the frequency and power requirements.
What is the role of insulation in a transformer?
To prevent electrical short circuits between windings and the core.
What is a laminated core transformer?
A transformer with a core made of thin, insulated layers of iron to reduce eddy current losses.
What are eddy currents in transformers?
Circulating currents induced in the core, causing power loss and heat generation.
What is a toroidal transformer?
A transformer with a doughnut-shaped core, offering higher efficiency and lower electromagnetic interference.
What is the impedance of a transformer?
The opposition to alternating current, determined by the winding resistance and leakage reactance.
What is a center-tapped transformer?
A transformer with a secondary winding that has a connection in the middle, providing two equal voltages.
What is a multitap transformer?
A transformer with multiple taps on the winding to provide different voltage outputs.
What is the purpose of a multitap transformer?
To provide multiple voltage levels for different circuit requirements.
What is a three-phase transformer?
A transformer designed to work with three-phase power systems, often used in industrial applications.
How are transformers cooled?
Through air, oil, or forced cooling systems to dissipate heat generated during operation.
What is a transformer regulation?
The change in output voltage from no load to full load, expressed as a percentage.
What is the primary purpose of transformer shielding?
To reduce electromagnetic interference (EMI) between the primary and secondary windings.
What is a leakage flux in transformers?
Magnetic flux that does not link both windings, reducing efficiency.
What are common applications of transformers?
Power distribution, voltage regulation, impedance matching, and isolation.
What can go wrong with transformers?
Overheating, insulation breakdown, core saturation, or winding damage.
What is core saturation in a transformer?
When the core’s magnetic material reaches its maximum flux density, causing distortion and inefficiency.
How do you test a transformer?
Use a multimeter to measure winding resistance, and apply test voltages to verify the turns ratio and functionality.
What is a harmonic distortion in transformers?
Distortion caused by non-linear loads, affecting transformer efficiency and performance.
What is the role of a transformer in voltage step-down applications?
To reduce high voltage to a lower, usable level for devices or circuits.
What is the purpose of a transformer in power isolation?
To separate two circuits electrically while allowing power transfer, enhancing safety.
What is the no-load current of a transformer?
The current drawn by the primary winding when the secondary circuit is open.
How do you calculate the power rating of a transformer?
Multiplying the secondary voltage by the secondary current, typically expressed in volt-amperes (VA).
What is a shell-type transformer?
A transformer with the windings surrounded by the core, offering better magnetic flux containment.
What is the difference between step-up and step-down transformers?
Step-down transformers increase voltage, while step-down transformers decrease voltage.
What is the purpose of a magnetic shunt in a transformer?
To control the amount of leakage flux and regulate the output voltage.
What is a split-core transformer?
A transformer with a removable core, used for current sensing without disconnecting the circuit.
How do transformers improve energy efficiency in power distribution?
By stepping up voltage to reduce current and minimize power loss during transmission.
