Magnetic Switch Design Archives

How an Environment Affects a Magnetic Switch

March 15, 2019 10:57 am Comments Off

A magnetic switch is a device that closes an electrical circuit when exposed to a magnetic field. The switch stays open until it’s impacted by magnetism. This switching mechanism is ideal for underwater deployment and conditions where electric sparking could trigger explosions or fires.

How Reed Switches Work in Different Environments

A magnetic reed switch can be used in a host of non-conventional, harsh conditions thanks to its inherent operational characteristics. For example, the device can maintain its magnetic sensitivity on exposure to shock and vibrations. It is a non-contact magnetic switch, making it suitable for use in hazardous locations, such as potentially explosive environments.

Hermetically sealed reed switches add to the safety of this electrical switch. Besides having simple circuitry, the magnetic sensor can detect a magnetic field while its contacts are safely contained in its hermetically sealed housing.

Several design factors impact the performance and operational continuity of a reed switch in a shock or vibration environment. These measures help prevent functional problems, such as:

False signal interference/responses
Tempering with the switches’ magnetic sensitivity
Breaking the glass capsule

Below are essential factors to consider when incorporating a magnetic reed switch into your design:

Temperature

Temperature changes impact magnetism by either strengthening or weakening a magnet’s pulling force. Heating a magnet decreases its magnetism by ramping up the speed and irregularity of atomic movements within its structure. On the other hand, lowering the temperature of a magnet expands its magnetic field and boosts its force of attraction.

Similarly, reed switch magnetism is stronger at a lower temperature and weaker at a higher temperature. Sporadic atomic movements surge as operating conditions get hotter, which leads to misalignment of the magnetic field. A reed switch’s operating sensitivity to a magnetic field (pull-in) goes up as temperature increases.

Magnetic Field Optimization

Magnetic fields are most impacted by ferrous material. Ferrous materials or other stray magnetic fields can affect how well the magnetic reed switch performs.

To boost your magnetic field provided by the trigger magnet, it is best to avoid installing it directly on ferrous material, like iron. If the magnetic switch is being installed on ferrous material, the impact can be minimized by inserting a non-ferrous material between the magnetic switch and its mounting location. Such spacers made from plastic, rubber, or even wood can help in this way.

Shock and Vibration

Inside the hermetically sealed glass enclosure of the magnetic reed switch are mechanical contacts that either make or break the electrical connection along the circuit’s signal path. When exposed to excessive mechanical shock, these contacts can be displaced, which can affect the performance of the magnetic reed switch.

It is best to identify potential areas of concern with regard to shock and vibration of the magnetic switch. Taking efforts early in the design process to eliminate or minimize these factors will result in better switch performance in your design. Consider repositioning the switch to avoid potential impact while installed on equipment. Additional rubber padding at installation can also help absorb excessive vibrations.

The mechanical design of a switch impacts its susceptibility to shock damage. Models to consider are:

Reed Switches: This devices have magnetic contacts contained in a glass tube. These contacts can be affected by excessive mechanical shock.
Hall Switches: These sensors are contained in a semiconductor device. As a result, they are less prone to malfunction due to mechanical shock. However, Hall sensors do require power in order to operate properly.

Anti-Shock Protection Offered in MagneLink’s Switches

Layers of potting compound are used inside the magnetic sensor’s housing to encase the glass enclosure of the reed switch. This provides considerable levels of vibration protection. The anti-shock material absorbs most of the impact, protecting the fragile reed capsule from substantial damage in the event of a fall, vibration, or shock. It is still recommended to avoid and minimize the effects of mechanical shock and vibration when selecting how and where the magnetic switch will be installed on your equipment.

MagneLink: Your Trusted Supplier of Long-Lasting Non-Contact Magnetic Switches

MagneLink is a leading innovator of advanced magnetic switch solutions, including hall and reed switches. We take pride in delivering reliable, customized non-contact switches to satisfy specific requirements across diverse industries—from waste recycling and transportation to machine tool equipment. Our switches are built for a long functional life and to withstand the harshest operating conditions, including extreme temperature and humidity.

For more information about our magnetic switches, contact us today.

Selecting a Magnetic Switch for Your Next Design

December 19, 2018 8:32 am Comments Off

Magnetic switches, as their name suggests, are devices that allow or disallow the flow of current based on the presence of a magnetic field. There are several types of magnetic switches, each possessing specific characteristics that lend themselves to different applications. When designing or selecting a magnetic switch, it is essential that parameters such as application type, circuitry and power requirements, magnetic sensitivity, and operating environment are carefully taken into consideration.

The most common types of magnetic switches in use today are Reed switches, Hall effect switches, and Triac or Transistor switches.

Reed switches consist of a pair of overlapping, but slightly separated metal contacts hermetically sealed in a small glass tube. When a magnetic field is present, the contacts are drawn together, completing the circuit.

Hall Effect switches are so named because they use the Hall Effect Principle to detect the presence of a magnetic field. When current flowing through the conductor is exposed to a magnetic field in a perpendicular direction, a potential difference (voltage) is generated in a transverse direction across it, thus triggering the switch.

Triac and Transistor switches are similar semiconductor devices with the ability to regulate the flow of current in a circuit. A Triac or Transistor switch, when used with a Reed or Hall Effect device, is triggered by small currents and voltages and is used to control significantly larger currents and voltages in an electrical circuit. Of all three switches, Triac or Transistor switches are the best suited for switching larger, or inductive-type, loads.

Magnetic Switch Applications

The construction and operating principles of the different switches make each suitable for different applications—although there are instances where there may be some overlap.

Reed switches are highly sensitive to magnetic fields, customizable, and are relatively low-cost compared to other switches. These switches are commonly used in proximity or limit switch applications, such as security alarms, doors in household appliances, cell phones, and doors on vehicles or heavy machinery.

Hall Effect switches are semiconductor devices. As such, they have no mechanical contacts. This gives Hall Effect switches an advantage of being less prone to damage due to mechanical shock. Hall Effect switches are commonly used as limit switches in actuators which can be found in factory automation equipment, elevator cars or vehicles.

Triac or Transistor switches are the most complex of these switch types, as they add more circuitry to the switch. Triac switches are designed for switching and power control applications in AC voltage systems, whereas Transistor switches are designed for switching and power control applications in DC voltage systems. Both switches are robust, making them ideal for more heavy duty, higher-current switching applications. They are commonly used for controlling relays, motors, or other inductive type loads.

Circuitry, Electrical Current, and Power Load Requirements

The Reed switch is the only one of the three switches that is considered a “dry contact” switch, and as such, is not required to be powered at all times. Due to the simplicity of Reed switches, they can be tested out of their circuit with a simple ohmmeter. Reed switches carry the switched current of the circuit when they make contact. Therefore, it is important to choose a reed with the proper Contact Rating for the power draw in the circuit. Choosing too small of a reed for a design could lead to a shorter switch life.

Hall Effect switches are ideal for low-to-medium DC power applications. They do require constant power to be supplied in order to function properly. Therefore, these switches need to be tested under load.

Triac and Transistor switches are best suited for higher power loads in AC voltage or DC voltage environments, respectively. Like the Hall Effect switches, they also need to be tested under load.

Magnetic Fields & Sensitivity

When determining which switch is best suitable for your application, it is important to understand how exposure to magnetic fields will impact your chosen equipment.

Reed switches

Reed switches are mechanical devices, meaning they are subject to excessive mechanical shock from impacts or vibrations in your operation that can disrupt magnetic fields. Reed switches are available in varying magnetomotive forces, measured in Ampere-Turns (AT), to suit the needs of a variety of applications. The magnetic sensitivity of a Reed Switch may vary based on the size of the reed, surrounding environmental factors, and the strength of the magnetic field applied.

Hall Effect switches

Hall Effect switches are semiconductors rather than mechanical devices, making them less prone to the risks posed by mechanical shock. In addition, they offer more options for application configurations, as they are available as Omnipolar or Unipolar options. Omnipolar devices can detect either the North or South poles of a magnet, while Unipolar devices sense only one pole. The magnetic sensitivity of Hall Effect switches depends on the electric current applied and the type of magnetic field generated.

Triac or Transistor switches

The current-carrying capacity of Triac or Transistor switches may be increased by using them in conjunction with Reed or Hall Effect switches. Of note, the magnetic sensitivity and mechanical benefits and limitations of the Reed or Hall Effect device used in the switching circuit will still apply.

Environment

At MagneLink, we take steps to make sure our Reed, Hall Effect, and Triac and Transistor switches are as durable as possible. All our switches are protected inside a housing filled with potting material, improving the mechanical durability of our switches and protecting them from environmental contaminants such as dust, weather, washdowns, and more.

We offer a range of switch housings designed for use across various commercial and industrial settings. We fabricate our standard housings from glass-reinforced resin, which has proven adept at withstanding the typical abuse switching equipment is subjected to in general operations. We also offer alternate housings such as die cast aluminum for the MLT housing, and stainless steel for our MLQ housing.

Switches for All Operations

MagneLink, Inc. has been a leading supplier of reliable magnetic switches for over 25 years. During this time, we have helped numerous clients across a broad range of industries with their magnetic switching needs. Our diverse offering of switches ensures that we are able to meet your requirements—regardless of the application. In the event a client has a unique application, we also offer custom design services.

If you would like to learn more about our products or services and how they can improve your operation, feel free to email us or call our sales team at 1-800-638-0801.

Get Your Free Quote

Latest News & Media

Tag Archive: Magnetic Switch Design