An Introduction to Coils

What is an Electric Coil? An electric coil, also known as an electromagnetic coil, consists of conductive wires wound around a ferromagnetic core, which can take the shape of a cylinder, toroid, or disk. As one of the most basic electronic components, electric coils provide inductance in electrical circuits, a characteristic that opposes the flow of current.

There are various types of electrical coils, which differ in aspects such as wire gauge, coil diameter, wire length, number of turns, and core material. Core materials may include air, iron, steel, ceramic, or iron-based amorphous tape. The selection of core material depends on its permeability, which influences the core's capacity to support and amplify the magnetic field.

Electric coils are utilized in devices such as electric motors, generators, inductors, and electromagnets. They act as conductors of electricity, effectively delivering electrical current to electric motors. This makes them a dependable and consistent method for inducing electrical energy.

Types of Coils

Electromagnetic Coils: These are commonly found in electrical devices. They are created by winding insulated copper wire around a core to generate inductance.  

Induction Coils: An induction coil comprises two coils of insulated wire wound around a shared iron core, used to convert low voltage current into high voltage.  

Voice Coils: These coils are attached to the apex of a loudspeaker cone and provide the driving force for the cone through the interaction of a magnetic field with the current flowing through them.

How Electric Coils Used?

Electric coils are commonly employed in industrial manufacturing, medical devices, and electrical systems for residential and commercial buildings. Their diverse applications lead to designs that cater to the specific needs of different processes and requirements.

Medical Electric Coils

Medical equipment must meet strict standards, particularly for components utilized in treatments. Manufacturers usually produce coils that comply with cleanroom standards to maintain high cleanliness levels. Medical coils are crafted from various materials to accommodate different applications and require very precise tolerances for inner and outer diameters to ensure dependable performance in critical situations.

Military Electric Coils

Military-grade coils must be dependable, precise, and highly responsive, capable of operating in harsh and hazardous environments. They are used in a range of military applications, such as guidance systems, navigation controls, and sensors.

Transportation Electric Coils

The transportation industry makes extensive use of electric coils across a variety of applications. They are found in railroad track transformers, lighting transformers, armatures, and signaling devices. Moreover, electric coils play a crucial role in manufacturing electric locomotives, where they are specially designed to withstand vibrations from continuous operation.

Energy Electric Coils

Manufacturing components for the energy sector comes with unique challenges, particularly due to the remote locations of many energy extraction sites. For example, oil platforms require dependable energy sources for electricity generation. The electric coils designed for these environments are specifically crafted to endure harsh conditions and rigorous demands.

Wind Powered Generator Electric Coils

Electric coils for wind turbines are designed to support generators producing from 100 W to over 1 MW. These coils can endure temperatures up to 200°C while ensuring optimal performance. Constructed from lightweight materials, they are also insulated to prevent leakage and damage.

Flowmeter Electric Coils

A flowmeter quantifies the volume of liquid or gas passing through a pipe, allowing for accurate monitoring and control of flow calculations. Bobbin-mounted flowmeter coils are specifically molded to match the radius of the tube being measured. As these coils are non-mechanical, they offer resistance to wear and abrasion.

Automotive Electric Coils

A fundamental component of an automobile is the ignition coil, which converts battery energy into the thousands of volts necessary to create a spark in the spark plugs, igniting the engine's fuel. Like most coils, ignition coils comprise two sets of copper wires wrapped around an iron core. Electrical energy from the core is sent to the distributor and then to the spark plugs. The coil's primary winding consists of thicker wire, while the secondary windings use thinner, lighter wire. The idea of the ignition coil dates back hundreds of years and was adapted for use in early automobiles.

Traffic Light Sensor Electric Coils

A traffic light sensor is made up of a coil connected to an inductance meter. When a car enters the sensor's detection area, it serves as the inductor's core, changing the coil's inductance. This alteration indicates to the traffic light that a vehicle is present.

Transformer Electric Coils

Transformers have transformed the way electricity is delivered. Originally, electricity was provided as direct current (DC), necessitating a large network of transfer stations for long-distance transmission. The introduction of alternating current (AC) enabled electricity to be transmitted over greater distances with fewer intermediate stations, with transformers playing a key role in this evolution.

Transformers facilitate the transmission of AC at high voltage and low current, which minimizes energy loss in the lines. They convert high voltage to low voltage while adjusting the energy level of the current. Utilizing multiple coils and electromagnetic flux, transformers feature primary windings on one side and secondary windings on the other to conduct electricity effectively.

Electric Guitar Electric Coils

An electric guitar coil serves as a transducer that converts the vibrations of the strings into electrical signals. The most prevalent designs are single coils and dual coils, like the humbucker. In the dual-coil configuration, two coils function together to "buck the hum," effectively canceling out electrical interference. These pickups generate a magnetic field around the guitar strings to capture their vibrations.