Solenoid coil

How solenoid coils work

• Solenoid coils work by applying an electric current to a wire winding. A magnetic field is generated by the energisation. This magnetic field is often used to trigger mechanical movements or switching operations.
• When the current flows through the coil, these movements can, for example, actuate a switch or attract a device, enabling various electrical and mechanical applications. As soon as the current is switched off, the magnetic field disappears and the solenoid coil returns to its original state, ensuring fast responsiveness for repeated applications.

Designs and types of solenoid coils

• Solenoid coils are available in various designs, including cylindrical, flat, toroidal and tubular coils, each catering for specific applications and requirements. Cylindrical solenoid coils are the most common design and are often used in relays and actuators, while toroidal coils have lower magnetic losses due to their shape and are used in transformers. In addition, coils with iron cores can increase the magnetic field strength, which makes them ideal for electromagnets and motors.

Solenoid coil performance parameters

• Resistance: The electrical resistance of the coil is decisive for the current consumption and can be influenced by the thickness of the wire and the number of turns.

• Inductance (L): The inductance of a coil is an important electrical parameter that indicates how well the coil is able to store electromagnetic energy when an electric current flows through it. It is often measured in Henry (H).
• Maximum temperature: Solenoid coils are designed for specific operating temperatures depending on the materials used. Overheating can lead to damage to the copper wire insulation and thus to functional failure.

Structure of the solenoid coil

• Copper wire: The wire is usually made of copper, as it has a high electrical conductivity, which influences the efficiency of the solenoid coil. The wire is often insulated to prevent short circuits between the windings.
• Coil former: The wire is wound around a coil former, which can be made of plastic or other insulating materials. These materials are important for concentrating the magnetic field and optimising the electrical properties.
• Core material: Many magnetic coils use a ferromagnetic core (e.g. made of iron or an iron alloy) to concentrate the generated magnetic field. The core ensures a higher magnetic flux density, which increases the efficiency of the coil.

Solenoid coil applications

• Electromagnets use solenoid coils to generate a strong magnetic field by applying an electric current, which enables a wide range of applications, such as in automation technology and mechanical engineering. They are often used to pull or push moving parts, enabling precise control of mechanisms in machines and devices.

• Electromagnets are also used in safety and holding devices, where they temporarily hold objects in place until the power is switched off.

Other applications:

• Relays: Solenoid coils are used in relays to control electrical contacts. When current flows through the coil, a magnetic field is generated that actuates a switch.
• Actuators: In automation technology and robotics, solenoid coils are used in actuators to control mechanical movements.
• Transformers: In transformers, solenoid coils are important for regulating voltage and controlling the flow of energy.

Environmental requirements for solenoid coils

• Solenoid coils must fulfil environmental requirements such as temperature resistance from -40 °C to +150 °C as well as sufficient moisture and dust resistance in order to function reliably. Corrosion-resistant materials are crucial for the service life, and the coils should be able to withstand vibrations and shocks in industrial applications. Electromagnetic compatibility (EMC) is also important to avoid interference with other electronic devices, while environmentally friendly materials and production processes are becoming increasingly important.