Transformer Glossary

Transformer glossary
The transformer is the use of the principle of electromagnetic induction to change the AC voltage device, the main components are primary coil, secondary coil and magnetic core. Main functions: voltage conversion, current conversion, impedance conversion, isolation and so on. Whether you're a beginner looking to understand the basics or an experienced practitioner seeking a refresher, this glossary will provide you with accurate explanations to delve deeper into the world of transformers.
Understanding the terminology associated with step-up and step-down transformers is crucial when delving into the world of electrical devices. One important concept to grasp is the primary and secondary voltage relationship. In a step-up transformer, the secondary voltage is higher than the primary voltage, allowing for voltage amplification. This type of transformer is commonly used in power transmission systems to increase voltage levels for efficient long-distance transmission.

On the other hand, a step-down transformer reduces the secondary voltage compared to the primary voltage, enabling voltage reduction for applications such as household appliances. By familiarizing yourself with terms like alternating current, kVA, and secondary winding, you can gain a comprehensive understanding of transformer operation and make informed decisions in various electrical systems.

Transformer Vocabularies List

(In Alphabetical Order)


Alternating Current (AC)
An electrical current flow of continuously changing polarity, which rises to a maximum voltage in one direction, decreases to zero and then sinks to the maximum voltage in the other direction before changing polarity once again. This pattern is referred to as a sinusoidal wave and the number of cycles per second is equal to the frequency, which is measured in Hertz.
Arc Voltage
The amount of voltage present between electrodes of different potentials or between an electrode and ground. The magnitude is determined by the distance between electrodes and the dielectric constant of the medium surrounding them.
Breakdown Voltage
The voltage at which an electrical breakdown occurs. It is also known as breakdown potential, sparking potential or sparking voltage. Breakdown voltage is the minimum voltage required to cause a substantial flow of electric current through an insulating material or gas, which would lead to a sudden increase in current flow, and a breakdown of the material or gas's electrical resistance.
Core Loss
Core loss is also known as iron loss. Core loss is a form of energy loss that occurs in electrical transformers and other inductors. Core losses do not include the losses due to resistance in the conductors of the windings, which is often termed copper loss. It does not vary with load and is hence also called constant losses. It mainly consists of eddy current and hysteresis losses.
Core Saturation
The condition that occurs when an inductor or step up and down transformer core has reached maximum magnetic strength. At this point, the magnetic flux density becomes constant even when the current in the coil continues to increase.
Electrostatic Shielding
Electrostatic shielding refers to the process of protecting a specific area or object from electrostatic fields or electrical interference by using a barrier or shield. This can be done by creating a conductive enclosure around the object or area, which absorbs or deflects the electrical energy, preventing it from reaching the protected area. This is commonly used in electronic devices, where electromagnetic interference (EMI) can disrupt or damage sensitive components, or in sensitive laboratory equipment where electrical noise can interfere with measurements.


Impedance is the measure of opposition that a circuit or electronic component offers to the flow of an alternating current (AC). It is the ratio of the voltage applied to a circuit or component to the current that flows through it. In simple terms, impedance is the total resistance to the flow of an AC signal in a circuit or component.
Inrush Current
Inrush current is the high surge of electrical current that occurs when an electrical device is first turned on. It is a temporary current that can be several times higher than the steady-state or normal operating current of the device. It is a common occurrence in many electrical and electronic devices, including motors, transformers, power supplies, and other equipment that uses capacitors or inductors.
kVA stands for kilovolt-ampere, which is a unit of electrical power equivalent to 1000 volt-amperes. It is commonly used to measure the apparent power of an alternating current (AC) electrical system, taking into account both the voltage and current of the system.
Load refers to the amount of work that a machine, device, or system must perform. In general, load is a measure of the demands placed on a system or device, and it can be used to determine its capacity or performance. Also a requirement of the kVA or VA from the transformer.
Magnetic Shielding
Magnetic shielding is the process of protecting a space or object from magnetic fields. This is achieved by placing a barrier made of a material with high magnetic permeability, such as iron or steel, around the object or space. This conductive material attenuates stray magnetic fields by its positioning around a power transformer's coils.
Power Factor
It is a measurement of the efficiency of an electrical system, representing the ratio of the real power (in watts) to the apparent power (in volt-amperes) consumed by a device. It is a number between 0 and 1, with a higher power factor indicating that more of the electrical power supplied is being used to do useful work, while a lower power factor indicates that more of the power is being wasted as heat or other non-useful forms of energy.


Reactance is a measure of opposition to the flow of alternating current (AC) caused by inductance and capacitance in an electrical circuit. It is a complex quantity that is expressed in ohms. Reactance can be either capacitive or inductive depending on the nature of the circuit element.
A condition of an AC circuit in which capacitive and inductive reactances interact, resulting in a maximum or minimum circuit impedance. It is the phenomenon of an object or a system vibrating at a particular frequency that is in harmony with an external stimulus or a natural frequency.
Secondary Winding
A secondary winding is a coil of wire that is wound around a magnetic core, which is separate from the primary winding. It is used in transformers to transfer electrical energy from one circuit to another. The secondary winding is connected to the load, and the voltage and current induced in it are determined by the ratio of the number of turns in the primary and secondary windings.
Step Down Transformer
A step down transformer is an electrical device that reduces the voltage of an alternating current (AC) power supply. It consists of a primary winding, a secondary winding, and an iron core. When an AC voltage is applied to the primary winding, it creates a fluctuating magnetic field in the iron core. This magnetic field then induces a voltage in the secondary winding but at a lower voltage level than the primary winding.
Step Up Transformer
A step up transformer is a type of transformer that converts the low voltage (LV) and high current from the primary side of the transformer to the high voltage (HV) and low current value on the secondary side of the transformer. The reverse of this is known as a step down transformer.