This article takes an in depth look at solenoid coils.
You will learn more about topics such as:
A solenoid coil is a widely used electrical component characterized by a wire that is closely wound around a core, typically composed of metal, to create an electromagnetic field. When electrical current flows through this coil, it generates an electromagnetic field that provides the necessary force for linear motion. Solenoid coils represent one of the most straightforward types of linear actuation devices.
Solenoid coils are highly versatile electromagnetic components fundamental to a wide variety of applications and industries, ranging from industrial automation to consumer electronics. As a core part of solenoid actuators, their primary function is to facilitate the automatic switching, locking, or movement of components within electrical circuits and mechanical systems. When electric current is applied to the solenoid coil, it generates a magnetic field that activates a movable armature, effectively engaging and operating the connected device or mechanism.
Due to their reliability and rapid response times, solenoid coils are integral to many types of automated and electromechanical systems. In industrial environments, solenoid coils are frequently used to operate hydraulic and pneumatic valves, industrial robotics, automated gate systems, and machinery requiring precise on-off or directional control. These coils are also essential for safety interlocks, high-speed sorting machines, and other process control systems where electrical signal conversion to mechanical motion is required.
Solenoid coils are a key technology in automatic locking systems, such as door locks designed for high-security facilities and restricted access areas. In these electromechanical locks, the solenoid coil remains uncharged while locked; when electrical power is supplied, the coil is energized, retracting the locking bolt and enabling access. This failsafe feature is crucial in access control systems, safe deposit boxes, and smart security solutions where remote or automated actuation is necessary.
Solenoid coils serve vital roles in the medical device sector, where long-term reliability, electromagnetic compatibility, and precise actuation are mission-critical. For instance, in dialysis equipment, solenoid coils control blood and fluid flow by actuating miniature valves. In automated medication dispensers, they permit exact dosing by opening or closing delivery channels on command. Other healthcare devices utilizing solenoid coils include oxygen therapy machines, diagnostic imaging equipment, infusion pumps, respirators, anesthesia systems, and gas chromatography apparatus. To meet stringent medical regulations, manufacturers employ advanced materials and rigorous quality controls in solenoid coil production, ensuring high isolation resistance, low power consumption, and fail-safe operation even under continuous duty cycles.
Solenoid coils are indispensable in the automotive industry, where increasing vehicle automation and electronic control systems demand rapid, reliable switching. Automotive solenoid coils are used in transmission shifters, starter motors, fuel injectors, anti-lock braking systems (ABS), and emissions control devices. In modern vehicles, solenoid coils regulate automatic transmission gear selection, control air conditioning systems, enable keyless entry and immobilizer systems, and activate entertainment or infotainment features. Their ability to provide precise, high-speed actuation contributes directly to vehicle safety, performance, and enhanced driver comfort.
In landscape management and agricultural irrigation, solenoid coils are vital actuator components controlling water valves. These solenoid valve coils allow irrigation controllers and smart timers to remotely start or stop water flow, optimizing water usage and supporting automated, scheduled irrigation cycles. Engineered for durability, irrigation solenoid coils are typically weatherproof, submersible, and compatible with various plumbing standards. They can operate in demanding outdoor environments, yet are sensitive to clogs; debris or sediment can cause the valve to stick in the open or closed position, resulting in water leakage or insufficient irrigation. Integrated filtration and routine maintenance can help avert such issues and extend system longevity.
Within aerospace technology, solenoid coils enable reliable power management and avionics protection. Aircraft utilize specialized solenoid relays or contactors to isolate sensitive avionics equipment from voltage fluctuations during engine startup. These aviation-grade solenoid coils are engineered to stringent standards for vibration resistance, electromagnetic interference (EMI) shielding, and high-cycle endurance. By precisely switching connection between the avionics bus and main power bus, solenoid coils safeguard critical flight electronics and communication systems, ensuring safe and stable aircraft operation.
Hydraulic solenoid coils are core components in hydraulic solenoid valves that control the movement and direction of hydraulic fluids in complex machinery. By energizing the coil, operators can remotely actuate valves to initiate, terminate, or change the direction of pressurized fluid flow for hydraulic cylinders, actuators, and motors. These devices are essential in industrial automation, construction equipment, injection molding, and heavy machinery applications where precision flow control and robust performance under high pressure are required. Key selection criteria for hydraulic solenoid coils include voltage rating, insulation class, power consumption, response time, and duty cycle, which help match a solenoid coil to system requirements for efficiency and safety.
Pneumatic solenoid coils are electromagnetically operated coils responsible for actuating valves in compressed air or gas systems. When activated, these coils open or close pneumatic solenoid valves, enabling or restricting airflow to pneumatic actuators, cylinders, or other devices. Pneumatic control systems use two-way, three-way, or five-way valve designs to achieve bi-directional or multi-position control, enabling high-speed automation, packaging machinery, conveyors, and air tools.
In more advanced systems, a pneumatic solenoid valve may feature dual coils to independently control separate flow paths, enhancing flexibility for industrial automation solutions. These electromagnetic coils are chosen for their fast switching, reliability, and ability to operate under varying temperature and pressure conditions within pneumatic circuits. Key factors in selection include voltage, coil resistance, and compatibility with valve manifold systems.
In the field of recreational technology, solenoid coils are the driving force behind pinball machines. These coils deliver rapid, forceful actuation—launching the ball with bumpers or propelling it with flipper arms. By retracting a metal plunger briefly and releasing it in quick succession, the solenoid coil provides the kinetic energy required for dynamic gameplay. Modern pinball machinery integrates high-performance solenoid coil assemblies to enhance operator control while incorporating safety features such as pulse-width modulation and thermal protection to prevent coil overheating and prolong service life. Proper coil timing is critical to ensure consistent performance and avoid mechanical wear.
Choosing the Right Solenoid Coil for Your Application
Selecting the ideal solenoid coil relies on application-specific factors including voltage requirements (AC or DC), coil resistance, insulation class, response time, duty cycle, and compatibility with the device it controls. It is also essential to consider environmental factors such as temperature range, exposure to moisture, chemical resistance, and the duty environment (continuous or intermittent operation). Leading solenoid coil manufacturers offer customizable and off-the-shelf options designed for diverse sectors such as automotive, industrial automation, fluid handling, and medical technology. When evaluating solenoid coils, consult engineering datasheets and leverage supplier engineering support to ensure optimal performance, longevity, and safety compliance for your automated system.
Explore a wide selection of high-quality solenoid coils and other electromagnetic actuators by consulting with experienced suppliers to guarantee reliable, efficient solutions tailor-made for industrial, commercial, or specialty equipment needs.
A solenoid coil is constructed by winding a wire, typically made of copper or aluminum, around a hollow core. These coils can operate on either direct or alternating currents and are compatible with various voltages, including 6, 12, 24, 120, and 220 volts. Low-voltage coils, under 24 volts, are suitable for smaller applications, whereas higher-voltage coils, above 24 volts, are used in industrial settings and heavy machinery.
The two primary types of solenoid coils are tape-wrapped and encapsulated. Tape-wrapped coils are used in less demanding environments where exposure to solvents and chemicals is minimal, such as in clocks, timers, pneumatic systems, and electronic circuits.
Encapsulated coils are sealed in protective materials like polyester, rubber, or epoxy. This encapsulation provides insulation, dielectric strength, and enhanced structural integrity, making these coils suitable for harsh and demanding conditions.
Copper wire is the most commonly used material for constructing solenoid coils due to its superior conductivity and flexibility. While other types of wire are available, none match the performance of copper. The copper wire classes best suited for solenoid coils are F, H, and N, as they possess the necessary characteristics and properties.
One crucial factor in using copper wire is its diameter. If the wire is too thin, it will increase the coil's resistance, reduce its efficiency, and potentially lead to overheating and burnout.
Class F copper windings can tolerate temperatures above 155°C and perform effectively in ambient conditions of 20°C, with media temperatures reaching up to 100°C.
Class H windings are capable of withstanding temperatures over 180°C and function reliably in ambient temperatures of 50°C with media temperatures reaching up to 180°C.
Class N windings are suitable for temperatures exceeding 200°C and can operate effectively at ambient temperatures of up to 80°C with media temperatures reaching 200°C.
The bobbin serves as the support structure for the wire, securing the lead wires to prevent strain. Beyond holding the wire, it also locates and guides the movement of the solenoid components and regulates the solenoid's stroke. Designed for durability, the bobbin features a low-friction surface and may include connectors, such as DIN connectors, for electrical current supply.
The winding of a solenoid coil is determined by factors such as circuit requirements, the desired inductance value, and the bobbin diameter. The number of windings directly influences the strength of the solenoid's magnetic field, with inductance increasing in proportion to the square of the number of coil turns.
Increasing the number of windings adds more magnetic field lines, enhancing the strength of the electromagnetic field. The field strength is affected by the number of coils, the type of wire used, and the wire's thickness. As the resistance decreases, more current can flow through the coil, resulting in a stronger magnetic field.
The core of a solenoid coil can be constructed from various ferromagnetic metals, which enhance the coil's magnetic power. While solenoid coils can function without a core, as seen in air-core designs, the core material significantly affects the magnetic field strength, with some cores amplifying it by up to 100 times.
Air cores, typically made from glass or plastic, do not increase magnetic field strength but offer high efficiency at elevated frequencies, reaching up to one gigahertz (GHz). In contrast, metal cores are limited to frequencies up to 100 megahertz (MHz).
The types of cores include:
There are two primary methods for protecting solenoid wires: wrapping and encapsulating. Wrapped solenoid coils are covered with paper or tape, whereas encapsulated coils are sealed within a solid, non-porous material. These methods offer distinct types of protection and durability.
Wrapped solenoid coils are covered with adhesive tape or paper around the magnetic wires. Most wrapped coils are protected by insulated tape to ensure proper insulation and durability.
Encapsulated solenoid coils are protected by solid materials such as epoxy, rubber, different forms of polyester, and plastic. These types of solenoids are referred to as molded and are capable of withstanding harsh and hazardous conditions.
DIN, which stands for Deutsches Institut für Normung (German Institute for Standardization), establishes standards used in various fields, including electronics. For solenoid coils, DIN connectors are used instead of lead wires and feature a male connector that plugs into a female socket. These connectors provide a more secure connection, facilitating easier coil replacement.
DIN connectors are most commonly used with encapsulated solenoid coils, as they can be seamlessly integrated into the bobbin design.
The primary function of a solenoid coil is to convert electrical energy into mechanical energy, producing linear motion. Its structure consists of a wire wound around a piston made of ferromagnetic material. Unlike a permanent magnet, a solenoid coil can be turned off, making it ideal for use in switches, valves, and automated systems.
Like all magnets, a solenoid coil has positive and negative poles that can attract or repel materials sensitive to magnetic forces. The magnetic field generated by the solenoid causes the core or piston to move forward or backward, enabling the activation or deactivation of various applications.
A solenoid coil functions by converting electrical energy into mechanical motion to provide linear movement. It consists of a wire wound around a piston made of ferromagnetic material. Unlike permanent magnets, solenoid coils can be deactivated, making them ideal for use in switches, valves, and automated systems.
Solenoid coils, like magnets, have positive and negative poles that attract or repel materials sensitive to magnetic forces. The magnetic field generated by the solenoid causes the core or piston to move, enabling the activation or deactivation of various applications.
Two primary elements in a solenoid coil are its magnetic field and electrical input. While a magnet can alter the position or direction of metal objects, it remains continuously magnetized. Solenoid coils, however, can control their magnetic fields through electrical activation, allowing for precise control.
All wires generate a weak magnetic field when electric current flows through them. To strengthen this effect, wires are wound into a coil in a solenoid. Each loop of wire enhances the magnetic field, producing a stronger effect than a single straight wire.
Every electrical device needs a closed circuit between the device and its power source. A switch provides a reliable means to break this connection. As power demands increase, the switch size must also increase. Despite this, activating and deactivating the switch requires minimal energy. Solenoids, therefore, efficiently manage this with minimal energy, such as a 24-volt solenoid operating a 240-volt machine.
If a standard switch were used for large equipment, it would require a very thick wire to handle the necessary power. Solenoids, however, require less power to operate than the devices they control, allowing for smaller, more cost-effective wiring.
The movement of a solenoid coil can activate or deactivate an application. This simple mechanism enables the control of large equipment with relatively low energy consumption.
Different designs of solenoid coils can achieve various outcomes. For example, in a door lock mechanism, a solenoid can stay engaged to keep the door locked. When an electric current is applied, the solenoid’s plunger retracts, unlocking the door.
Proportional solenoid coils convert an electric signal into proportional mechanical force, allowing for adjustments in position and force based on the current. These coils are used for regulating flow rates by adjusting the position of a valve’s plunger.
There is a vast range of solenoid coils designed for nearly every possible application. These coils differ in design, materials, and intended use. Despite the variety and specific applications, all solenoid coils function based on the same electrical principles.
Solenoid coils are frequently employed as solenoid valve coils for fluid control. They are also integral to automated machinery and robotic systems. Besides being categorized as wrapped or encapsulated, solenoid coils are further classified by their power source: alternating current (AC) or direct current (DC). The choice between AC and DC depends on various factors related to the specific application of the coil.
An AC solenoid coil is capable of delivering a substantial amount of force on the initial stroke due to the high current input when activated. This characteristic enables the coil to produce multiple strokes effectively. AC laminated solenoid coils come in various configurations and typically produce a buzzing sound. They are well-suited for applications needing rapid response, such as in medical devices, automotive systems, printers, and household appliances.
The C frame of a DC solenoid coil features an open frame design to enable linear motion. It represents one of the simplest and most cost-effective solenoid configurations while delivering high performance. Available in both push and pull configurations, it is commonly used in straightforward applications such as circuit breakers, scanners, coin counters, and point-of-sale devices.
A linear solenoid coil, also known as a linear electromechanical actuator (LEMA), can operate in either a continuous or an on/off mode. LEMAs may be designed as proportional solenoid coils, adjusting the plunger's position based on the power input. The term "linear solenoid coil" refers to the linear motion of the plunger when the coil is activated.
Solenoid coils are typically linear devices that move back and forth. Rotary solenoid coils, however, convert linear motion into rotary motion using three ball bearings.
When energized, the armature of a rotary solenoid coil is drawn toward the stator and rotates through an arc. These coils generate angular or rotary motion, which can be in a clockwise, counterclockwise, or bidirectional manner.
The rotational movement of a rotary solenoid coil can be 25°, 35°, 45°, 60°, or 90°, or it can involve multiple movements at specific angles. This rotary motion can be produced when the coil is energized, de-energized, or when there is a change in the polarity of the electromagnetic field.
A DC D frame solenoid coil is encased in two D-shaped frames on either side. This design provides a slightly higher force output and better resistance to environmental factors. D frame solenoid coils feature an economical design suitable for high-volume applications and continuous duty, and they are available for both on and off operations.
The various sizes and stroke options of a DC D frame solenoid coil enable it to deliver reliable performance over several million cycles.
The role of a solenoid valve coil is to regulate the flow of fluids in tubes, ducts, and pipes. There are multiple types of solenoid valve coils, each designed to address the specific requirements of different fluid flow applications.
Direct acting solenoid valve coils feature a plunger that seals a small orifice without requiring additional force. This type of coil operates quickly, can function under pressure, and can be configured as either an open or closed valve coil.
A pilot operated solenoid valve coil, also known as an indirect acting coil, utilizes pressure across the valve port to control the valve's opening or closing. When energized, the coil opens the valve, while the system's pressure maintains the valve in a closed position.
A two-way solenoid valve coil features two ports that can open or close to regulate fluid flow. These valves are used in applications where controlling the release or restriction of fluids is necessary, such as in air compressors.
A three-way solenoid coil includes three ports and two openings that alternate based on the coil's requirements. Two of the ports serve as inlets, while the third port acts as an outlet. This configuration allows for the control of two different fluids.
A four-way solenoid valve coil features an additional port, with two ports serving as inlets and the other two as outlets. This design is used to operate double-acting solenoid valve actuators.
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...
An electromagnetic coil is an electrical coil that generates an electromagnetic field when electric current passes through it. The structure of an electromagnetic coil consists of a length of wire that...
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 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...
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 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...
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...
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...
Electric transformers are static electrical machines that transform electric power from one circuit to the other without changing the frequency. An electrical transformer can increase or decrease the voltage with...
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...
An electromagnetic interference or EMI Filter is an electrical device or circuit that filters specific unwanted frequencies in power lines or offending frequencies that are detrimental to a system. They receive AC or main power...
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...
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...
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...
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...
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...
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...
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...