What do street lamps, large motors, data centers, and stadiums have in common? They all rely on ready access to electricity—and lots of it.
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But getting electricity for a specific purpose isn’t as simple as hooking up directly to the power lines. The high voltage electricity in power lines is only suitable for transmitting power over long distances. To be usable in everyday applications, the electricity must pass through a transformer which converts the power to a suitable voltage.
Many people know what a transformer looks like. Understanding how they work, though, is a different story. Whether you’re budgeting for a transformer or installing one, knowing what transformers do and how they work provides greater clarity on what you need. In this article, you’ll find an introduction to transformers, why we need them, how they work, and a run-through of their most important parts.
In the simplest of terms, a transformer is an electrical device that takes a given input voltage and changes it to a different output voltage. This change can either be an increase or a decrease in voltage.
Electrical energy consists of two key elements: current and voltage.
Think of electricity as water flowing through a pipe.
To move water from the city reservoir to homes, businesses, and factories, you need a big pipe and a lot of water pressure. City water lines are built to handle huge volumes of water and that water moves quickly because of powerful water pressure.
Now imagine hooking up a high-volume, high-pressure city water pipe directly to your kitchen sink. The faucet would burst as soon as you turn it on and you’d have a river gushing into your house. To be usable, the water pressure from the main water line must be reduced using pressure regulators.
Once the water pressure has been reduced, it can finally be used for showers, cleaning dishes, watering your garden, and any other household and business chores.
Transformers do the same thing to electricity. The electricity running through power lines can exceed 300,000 volts—a massive amount of “electrical pressure”. Transformers make electricity usable by lowering the voltage at the point of use. These types of transformers are called step-down transformers.
These range from massive substation transformers found in utility substation yards, to those big green padmount transformers sitting outside your business, to small polemount transformers found atop power poles.
Commercial and industrial operations use large transformers, which provide three-phase voltages like 480 or 208 volts. Homes and small businesses use smaller single-phase transformers to provide 120/240v single-phase. Here, we will focus on three-phase distribution transformers.
A transformer functions under the law of energy conservation, which states that energy can neither be created nor destroyed, only transformed. Therefore, a transformer does not make electricity, it merely changes the voltage to suit the needs of the user.
Transformers accomplish this change in voltage through the process of electromagnetic induction.
Electromagnetic Induction
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When you run an alternating electric current through a wire (conductor), an invisible, moving magnetic field is created around the electrified conductor. When you place a second conductor within this changing magnetic field, the moving flux lines in the field induce a current in the second conductor.
You can use electromagnetic induction to increase or decrease voltage between the two conductors by wrapping the two conductors into coils with one being longer (having more loops in the coil), and the other shorter (having fewer loops in the coil). If you then electrify the coil having more loops, a current will be induced in the coil with fewer loops at a lower voltage than is present in the first coil.
The first coiled conductor where electricity enters the transformer is called the primary coil, and the other coil where current is induced is called the secondary coil. Both the primary and secondary coils (also called windings), made of aluminum or copper, are wrapped around an iron core which strengthens, and directs the changing magnetic field for better induction. As the magnetic field activates, the metal core expands and contracts. This movement creates the transformer humming or buzzing sound.
Each loop in the coil around the iron core is called a “turn”.
How do we get the exact voltage that we need? First, we have to understand one simple rule: the ratio of turns between the primary and secondary coils determines the ratio of voltage between the coils.
If the ratio of turns between the coils is 25:1, then the voltage will be transformed at a ratio of 25:1. To get the precise voltage you need, you would build a transformer with the exact desired ratio of turns in each coil. A transformer with a turns ratio of 25:1 would be used to transform 12,000 volts to 480 volts.
Three-phase transformer coils are connected in either a delta or a wye configuration.
A transformer is a crucial component in power supply systems. It is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. Transformers are used to increase (step up) or decrease (step down) voltage levels, which is essential for efficient power transmission and distribution. By converting voltages, transformers help reduce energy losses during long-distance transmission, ensuring that power reaches its destination effectively.
Transformers consist of primary and secondary windings wrapped around a magnetic core. When an alternating current (AC) flows through the primary winding, it creates a magnetic field that induces a voltage in the secondary winding. This process allows the transformer to modify voltage levels without changing the frequency of the current. Understanding the basic function of transformers is fundamental for anyone involved in the power industry.
Safety and isolation are critical aspects of power supply systems, and transformers are integral to achieving these goals. Isolation transformers, in particular, are designed to provide a physical barrier between primary and secondary circuits, which is essential for preventing direct electrical contact and enhancing safety.
Isolation transformers are widely used in industrial applications to protect both equipment and personnel from electric shocks. By providing electrical isolation, these transformers reduce the risk of electrical accidents, making them indispensable in environments where safety is a top priority. In addition, isolation transformers help in isolating faults within the power system. If a fault occurs in one part of the circuit, the transformer can contain it, preventing the fault from spreading to other parts of the system. This containment helps maintain the stability and safety of the entire power network.
Transformers also contribute to safety by ensuring proper voltage levels are maintained, preventing overvoltage or undervoltage conditions that could damage equipment or pose safety hazards. The role of transformers in fault management and electrical isolation underscores their importance in maintaining a safe and reliable power supply.
Transformers are used in a wide range of applications across various industries, reflecting their versatility and reliability. In the power generation sector, transformers are essential for stepping up the voltage from power plants for efficient long-distance transmission. This minimizes energy losses and ensures that electricity reaches its destination effectively.
In the distribution sector, step-down transformers reduce the high transmission voltage to safer levels for residential and commercial use. This ensures that electrical devices operate safely and efficiently. Transformers are also critical in industrial applications, where they provide the necessary voltage levels for operating heavy machinery and equipment. They are used in various industries, from manufacturing to mining, to ensure proper voltage levels and enhance equipment performance.
Transformers are also pivotal in renewable energy systems. For example, in wind and solar power installations, transformers convert the generated electricity to appropriate voltage levels for grid integration. This ensures that renewable energy can be efficiently distributed and utilized. The extensive use of transformers in different sectors highlights their importance in modern power supply systems, supporting a wide range of applications and contributing to the overall efficiency and reliability of electrical networks.
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