This article will take an in-depth look at electric transformers.
The article will bring more detail on topics such as:
This section delves into electric transformers, detailing their construction, operational principles, and functionality.
Electric transformers are stationary devices that facilitate the transfer of electrical power between circuits while preserving the same frequency. These systems are specifically designed to alter voltage levels, either increasing or decreasing them, which inversely affects the current flow. The functioning of a transformer is grounded in the principles of electromagnetic induction and mutual induction.
The functioning of electric transformers is dictated by Faraday's laws of electromagnetic induction. The core concept is that electricity can generate magnetic fields, and vice versa, magnetism can induce electricity.
Magnetism is a critical factor in all electrical systems. Transformers exploit magnetic properties to modify voltage levels, either amplifying or reducing them. By manipulating the magnetic field strength within the transformer, electrical force and power changes are induced. When a conductive wire, like copper, is part of this process, electrons are set in motion, enabling electrical transmission.
Transformers can modify voltage levels based on the coil configurations around their core. As alternating current traverses the transformer, the magnetic field varies. The core is wound with an output wire, and the changing magnetic field induces a current within this wire.
For distance electricity transport or between power plants, it must move at elevated voltages to cover significant distances efficiently. Upon reaching the destination, the voltage is reduced to prevent equipment damage and minimize electrical risks. Smaller substations at power plants incrementally reduce high voltages to manageable levels. On a local scale, including in residential areas, transformers further decrease voltage levels to those appropriate for household devices, such as stoves, air conditioners, laptops, heaters, and televisions. In industrial settings, where machinery often requires higher voltages, transformers are typically used to elevate voltage to meet these demands.
To decrease voltage, a transformer needs more turns of wire on the primary compared to the secondary winding. Conversely, to increase voltage, fewer turns on the primary are required compared to the secondary winding. It is rare for both windings to have an equal number of turns since this would simply convey the existing voltage without changes.
Though all transformers incur some energy loss—primarily as heat—they are challenging to manage and cool due to their static nature. Excessive heat could damage or deteriorate the insulation on a transformer’s wiring. Cooling is generally achieved in two ways: air and oil cooling. Air cooling involves directing airflow over coils to dissipate heat. Alternatively, ambient air can carry away heat by flowing through the coils. Immersing a transformer in oil or water is another effective cooling method. These sets of coils, or windings, in an electric transformer, are connected by a magnetic core, typically built from iron or ferrite material, and laminated with copper or enamel-coated materials.
An electric transformer relies on several essential components for optimal performance, as detailed below.
The core sustains the primary and secondary windings while providing a path of low reluctance for electromagnetic flux. Constructed from thin sheets of high-grade, oriented steel separated by insulating material, the core minimizes hysteresis and eddy currents. Its steel composition has a carbon content below 0.1%, with silicon inclusion to further curb eddy currents. In a three-phase transformer, each of the core’s limbs accommodates the primary and secondary windings for each phase, interconnected by magnetic yokes. The core can be assembled in two primary forms: core type or shell type, wherein the core encompasses the windings.
Each transformer phase includes a primary and a secondary winding. Multiple turns of copper or aluminum conductors make up these windings, insulated from each other and the core. Factors like current rating, short circuit strength, temperature rise, impedance, and voltage surges determine the winding configuration and type.
The high voltage rated winding is termed the HV winding, while the lower voltage rated winding is known as the LV winding.
High voltage windings generally have thinner conductors compared to low voltage windings, which are placed nearer to the core. Shell-type transformers may have HV windings positioned between LV coils and sectioned into multiple segments. Core-type transformers classify windings into four types, with selection based on factors like current capacity and turns number.
Because inadequate insulation can cause serious damage, it is essential in transformers. Materials chosen for insulation must provide high dielectric strength, resist high temperatures, and possess strong mechanical properties. Common insulating options include cotton, synthetic fibers, and paper, which are placed between windings, the core, and between active parts.
The tank serves dual roles: safeguarding the core and windings from external environmental influences and housing the oil. It also offers support for other components and accessories.
Typically, steel plates are fashioned into container shapes to create these tanks, but aluminum sheets might be used to save weight, despite the higher cost of aluminum over steel.
Transformer oil serves multiple functions in oil-immersed transformers: it enhances insulation between conducting parts, aids in cooling, and helps identify faulty areas.
Transformers use internal terminals to link incoming and outgoing cables. These terminals connect through bushings positioned at the winding ends. Bushings act as insulators, separating terminals from the tank and offering a secure pathway for conductors that connect terminals to windings. Epoxy resins and porcelain are common bushing materials.
Positioned above the tank and bushings, the oil conservator features a rubber bladder to accommodate oil expansion and contraction from temperature changes. A level indicator shows the oil level, and a pipe links the conservator to the main tank.
Breathers in oil-immersed transformers keep the oil dry. As temperature-induced contractions and expansions occur, air flowing in and out of the conservator tank passes through a silica gel-equipped breather to ensure moisture-free air inflow.
Heat generated during power dissipation in a transformer requires efficient management. While dry-type transformers rely on ambient air, oil-immersed versions use various cooling methods. Fans and radiators may be installed based on power rating, loss, and cooling necessities. The cooling process transfers heat from core and windings to the oil, dissipated through radiators. Large transformers might use forced cooling with radiators integrated for optimal heat dispersion.
An explosion vent releases oil and gas buildup in a transformer. Located above the conservator tank, it features a metal pipe with a diaphragm. When internal oil pressure becomes unsafe, the diaphragm bursts, safely venting excess pressure to the atmosphere.
Tap changers adjust secondary transformer voltage by altering the turns ratio. On-load tap changers adjust without halting current flow, while off-load versions are used when transformers are not active.
In oil-immersed transformers over 500 kVA, the Buchholz relay detects issues by monitoring for gases from oil decomposing due to short circuits. Upon gas detection, it signals an alarm and trips the circuit breaker to stop current flow.
Besides these components, larger transformers may feature additional elements such as pressure and temperature sensors, heat exchangers for optimal cooling, and protection relays.
All transformers operate based on Faraday's laws, but they can be classified or designed in different ways according to their specific applications and requirements.
These types of electric transformers are considered highly efficient due to their use of multiple iron plates with excellent magnetic properties.
In this type of electric transformer, the magnetizing and demagnetizing processes happen quickly, making it a highly preferred option. The iron plates are usually made of silicon steel and coated with insulating paint to minimize heat generation during the transformer's operation.
All electric transformers use the process of induction to convert electricity, rather than a direct conductive connection. Therefore, they can technically be classified as isolation transformers. The primary function of an isolation transformer is to transfer electrical power from one source to another device, isolating the electrical device from the power source. While they share similarities with other types of transformers, isolation transformers are specifically designed to isolate electricity or the electrical device from the power source. Some applications of isolation transformers include... isolation transformer ...include use in uninterruptible power supplies, robotics, test and measurement systems, motor controls and industrial control panels, and data communication systems.
These electric transformers efficiently manage energy loss in high-frequency applications due to the use of ferrite cores with high magnetic permeability. They feature an E-type configuration and can be customized and shaped to suit various functions.
These transformers are ideal for applications such as power transformation and modification, as they efficiently convert lower voltages to higher voltages while reducing amperage and minimizing resistance effects. The conversion process involves electrical energy passing through two sets of coils, with the second set having more windings, forming a complete coil assembly. Some applications of step-up transformers require only a single set of windings, while others may need an additional tertiary set of windings.
All electric transformers require two sets of coils to complete the conversion process. These coil windings are mounted on a core made of ferrite compound or a laminated core, with the coils themselves being either enamel-coated or bare copper. Step-up transformers utilize coil windings made from alloys such as aluminum, nickel, copper, chromium, and steel, which enhance their energy efficiency.
The voltage of a power transmission line refers to the measure of power transmission capacity in a transmission line. And these High voltage transformers are used to modify the voltage levels in power lines within high voltage contexts. These transformers handle voltages ranging from 600 to 5000 volts, where a volt measures electromotive force. High voltage electric transformers are commonly used for metering and providing protection in high voltage circuits. They are also utilized in electrostatic industrial and scientific applications.
These transformers have a donut shape, which helps minimize induction leakage by creating high inductance within the system. They feature short windings and are lighter than other transformers of the same rating. However, their winding process is slower, making them more expensive.
These transformers, which lack a magnetic core, are typically used in applications like radios and small electronic devices. They operate through flux linkage between two magnetically coupled coils or windings: the primary and secondary. The transformers generate flux using their windings and the surrounding air. For winding the coils, materials with low magnetic permeability, such as plastic tubing and cardboard, are used.
Laminated core transformers feature a core made from laminated sheets of iron and nickel. The addition of nickel helps to reduce energy losses when the winding is energized. A major advantage of laminated core transformers is their ability to minimize eddy currents, which improves the efficient transfer of energy from the primary coil to the secondary coil.
These transformers operate with direct current (DC) because their flux density remains constant and does not cross zero. Pulse transformers are commonly used to connect load resistance with a pulse power source. For instance, they are employed in radar systems, including those on submarines, where radar transmitters need high voltages and high impedance, often with output tubes like magnetrons. Small pulse transformers can produce electrical surges, making them suitable for telecommunications and specialized applications such as camera flashes and radar equipment. Medium-sized pulse transformers are used in applications requiring electric circuits.
Current transformers are well-suited for measuring the flow of electricity in transmission lines. Unlike power transformers, which control voltage, current transformers are specifically designed to measure and monitor current flow for measurement purposes. Understanding their operation is crucial, as current transformers can also be used to regulate the flow of electricity to electronic devices.
These are power transformers and they are used to change the voltage capacity which is contained in a low voltage electrical transmission line. Compared to high voltage transformers these low voltage transformers are small enough that they can be held between two fingers as they also have a low weight. In most cases, these low voltage transformers transfer or convert 120 volts into 12 volts or 24 volts.
These electric transformers have a single winding, making them highly cost-effective. In autotransformers, this single winding serves as both the primary and secondary coil and features three taps for electrical connections. The advantages of autotransformers include their compact size, lower cost, and lighter weight. They are especially useful in systems with varying voltage levels.
Polyphase transformers have three or more conductors, with configurations that can extend up to 15 phases. They feature multiple windings on both the primary and secondary cores. Many polyphase transformers use a zigzag configuration, especially when grounding is required.
This is a type of electric transformer that can be used to derive a reference point for use in underground systems. The zig zag transformer is used in a number of industries due to its ability to provide a neutral point for grounding purposes. Some of the areas of use include petrochemicals, power distribution, and automotives. Zig zag transformers contain a primary coil but do not have a secondary coil although they all in all consist of six coils on three separate cores. The windings of a zig zag transformer are in two halves because the way the two halves of the windings interconnect results in the difference in winding patterns while connecting the coils and the core.
This transformer is classified as a polyphase transformer. While it is possible to create a three-phase transformer by connecting three single-phase transformers, using a dedicated three-phase transformer is more cost-effective. A three-phase transformer has three sets of primary and secondary windings, which can be arranged in delta or star configurations, such as delta-delta or star-star.
Three-phase transformers are crucial for directing and controlling electrical current from power lines to homes and businesses. A current transformer manages the flow of current from the electrical line to the areas or equipment that will use it. Power transformers are generally most effective and safe for operating electrical systems and individual appliances.
This type of transformer serves as a link between the grid and generators, transferring energy to substations. Due to its large size, it requires cooling, which is achieved using oil and cooling agents.
The system they use is costly due to its three-phase setup. However, despite the higher expense, it is more efficient than single-phase systems. These transformers are categorized into three groups based on their voltage ratings.
These transformers can act as step-down transformers, reducing high voltages to low voltages by transferring electrical energy through two coil stages, with the second stage having fewer windings. The amount of power generated may vary depending on the geographical location.
These transformers are used to isolate main power and voltage, and then convert it to a smaller ratio.
This chapter will discuss the applications and benefits of electric transformers.
Electric transformers are essential in our daily lives, as they adjust electrical current to meet the needs of various appliances. They manage voltage flow during charging, preventing unregulated voltage from causing electrical surges. This regulation helps safeguard appliances from potential damage.
Electric transformers are crucial in steel production, where they provide high voltages for melting and welding while delivering lower currents for cooling. In chemical processing, transformers are essential for powering electrolysis, which is used in processes like electroplating metals such as aluminum, copper, and zinc. They regulate the electrical current that drives these chemical reactions, ensuring precise control.
Electric transformers are cost-effective, providing a reliable and affordable solution for voltage transmission and isolation. Their various types enable a wide range of applications; for example, current transformers step down currents for measurement instruments. Additionally, transformers can be configured as either step-up or step-down devices, depending on their installation. Some models feature multiple taps on the primary winding to accommodate different input voltages.
Electric transformers require cooling because energy losses produce high temperatures that can reduce the lifespan of the insulating materials in the windings. They are not designed to handle direct current (DC). Maintenance can be challenging, as transformers are susceptible to issues such as oil leaks, overloading, and harmonics, which can cause damage.
Electric transformers are devices that transfer electricity between circuits by adjusting voltage levels while keeping the frequency constant. They are designed for use with alternating current (AC), so changes in supply voltage are affected by changes in supply current. Transformers can either step up or step down voltage levels, providing a safe and efficient power system for both industrial and residential applications.
An isolation transformer, just like typical transformers, is a non-moving device that transmits electrical energy from one circuit to another without requiring any physical contact. It works on the idea of magnetic...
Power transformers are electrical instruments used in transmitting electrical power from one circuit to another without changing the frequency. They operate by the principle of electromagnetic induction. They are used in transmitting electrical power between...
An electrical transformer is a passive machine that transfers electrical energy from one circuit to another using a magnetic flux to induce an electromotive force. Transformers are used to increase (step-up) or decrease (step-down) voltages without changing the frequency of the electric current...
A toroidal transformer is a type of electrical transformer constructed with a torus or donut-shaped core. Its primary and secondary windings are wound across the entire surface of the torus core separated by an insulating material...
Electronically operated equipment depends on power transformers to convert electrical currents into voltage. Current transformers store and transport energy through power lines and grids...
Power supplies are electrical circuits and devices that are designed to convert mains power or electricity from any electric source to specific values of voltage and current for the target device...
An AC power supply is a type of power supply used to supply alternating current (AC) power to a load. The power input may be in an AC or DC form. The power supplied from wall outlets (mains supply) and...
An AC power cord is a detachable way of providing an alternating current of electric energy from a mains power supply to an electrical appliance or equipment. Serving industries like...
A DC DC power supply (also known as DC DC Converter) is a kind of DC power supply that uses DC voltage as input instead of AC/DC power supplies that rely on AC mains supply voltage as an input...
A DC power supply is a type of power supply that gives direct current (DC) voltage to power a device. Because DC power supply is commonly used on an engineer‘s or technician‘s bench for a ton of power tests...
An electric coil, or electromagnetic coil, is an electrical conductor that contains a series of conductive wires wrapped around a ferromagnetic core that is cylindrical, toroidal, or disk-like. Electric coils are one of the simplest forms of electronic components and provide...
Electrical plugs, commonly known as power plugs, are devices responsible for supplying and drawing current from a receptacle to the circuitry of an electrical appliance...
By definition a power supply is a device that is designed to supply electric power to an electrical load. An electrical load refers to an electrical device that uses up electric power. Such a device can be anything from...
Inductors are passive two terminal components of an electric or electronic circuit that are capable of storing energy in magnetic form. They oppose sudden changes in current and they are also called coils or chokes...
A NEMA connector is a method for connecting electronic devices to power outlets. They can carry alternating current (AC) or direct current (DC). AC current is the typical current found in homes, offices, stores, or businesses...
A power cord is an electrical component used for connecting appliances to an electrical utility or power supply. It is made from an insulated electrical cable with one or both ends molded with connectors...
A programmable power supply is a method for controlling output voltage using an analog or digitally controlled signal using a keypad or rotary switch from the front panel of the power supply...
A solenoid coil is a common electrical component that uses a wire that is tightly wrapped around a core, usually made of metal, to generate an electromagnetic field. When an electrical current is passed through the coil, the electromagnetic field that is created provides energy for linear motion...
A voice coil is a winding of a wire, usually copper, aluminum, or copper-clad aluminum that is wrapped around a former (often called a bobbin) and then attached to the apex of a speaker cone...
Thomas Edison developed the power distribution system in 1882. He wrapped a copper rod in jute, a soft shiny fiber from plants, as an insulator. The jute wrapped copper rod was placed in a pipe with a bituminous compound...