This section provides an overview for solid state relays as well as their applications and principles. Also, please take a look at the list of 12 solid state relay manufacturers and their company rankings.
Table of Contents
Solid State Relays are contactless relays that use semiconductors to transmit input signals to output circuits.
Generally, they are suitable for situations where relays are frequently opened and closed and high-speed response is required since high response and long life can be established.
Solid State Relays are used in situations where the on/off frequency is high, such as in temperature control systems, where their high responsiveness and long life can be maximized.
In addition, unlike general contact-type relays that use magnetic force, there is no mechanical sliding contact. Since no noise is generated by the opening and closing of the contacts, they are often incorporated into products that are vulnerable to noise.
On the other hand, the transmission of signals uses light emission phenomena via semiconductors and diodes. Therefore, there is no small amount of temperature rise effect and the output stage is a semiconductor device. Care must be taken because some parts are not suitable for products with high voltage and high current.
Figure 1. The principle of semiconductor relay
As the relay is said to be contactless, the circuit on the input side is physically isolated from the circuit on the output side, and the signal is transmitted through an opto-isolated device such as a photocoupler.
When an electric current is applied to a light-emitting diode on the input side, the diode emits light, and a circuit on the output side receives the light, and the output circuit operates when the light is detected. Depending on the supplier of Solid State Relays, photodiode arrays, photocouplers, and phototriacs are used for the light-receiving circuit, and variations such as MOSFETs and triacs exist for the output section.
The use of light for signal transmission provides a very fast response. Also, since they do not have mechanical contacts, the contact parts do not wear out, and they generally have a longer service life than contact-type relays.
Other features include the fact that the input and output are completely insulated by an insulating element, so noise generated on the input side is less likely to be transmitted to the output side.
First, it is necessary to consider how much responsiveness is required in the circuit where the relay is needed and how often the signal is transmitted. If you do not need such high responsiveness and only low-frequency signal transmission, general contact-type relays are often smaller and less expensive.
If a Solid State Relay is required, also check the maximum current value of its input signal. Since Solid State Relays are output circuits using semiconductors, excessive current flow will damage the semiconductors themselves, rendering them unusable for further use.
Figure 2. Semiconductor relay and mechanical relay
The difference between a Solid State Relay and a Mechanical Relay is whether they are contactless or contactless types. Semiconductor Relays, also called Solid State Relays, are contactless relays, while Mechanical Relays are contact relays.
Solid State Relays with no contacts are switched on and off by signal transmission only, with no mechanical closing or opening in the electronic circuit. A mechanical relay with contacts has movable parts built into the circuit and uses a coil to generate an electromagnetic force that causes the contacts to make contact and switch ON/OFF.
Solid State Relays and Mechanical Relays each have the following features, which can be used according to your needs.
Solid State Relays have the advantage of being compact and capable of opening and closing at high speeds, and they do not suffer from contact wear and failure as mechanical relays do. On the other hand, mechanical relays have almost no ON resistance, and their strength is that they can be easily used in circuits with high voltage and high power.
Automobiles are equipped with many relays as parts that control the operation of lamps, windshield wipers, audio equipment, motors, blinkers, and so on. In general, mechanical relays have been used for automotive relays.
However, mechanical relays have the disadvantages of limited contact life and large installation space. In recent years, the number of electrically driven in-vehicle devices has been increasing due to the need for low fuel consumption and low power consumption and the multifunctional nature of advanced technology, which has created a need for smaller and lighter relays.
Figure 3. Example of automotive semiconductor relay specifications
Solid State Relays have been developed for automotive applications to overcome the shortcomings of mechanical relays and are gradually replacing them. Figure 3 shows an example of Solid State Relay specifications for automotive applications.
The use of Solid State Relays has made it possible to reduce size and weight, which not only secures space in the vehicle but also contributes to improved fuel efficiency. In addition, the use of high current, which has been a bottleneck, can now be handled thanks to low ON-resistance achieved through advances in semiconductor technology.
*Including some distributors, etc.
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Sensata Technologies was originally founded in 1916 as General Plate Company and is now headquartered in Attleboro, Massachusetts. The company is a developer, manufacturer, and seller of sensors and sensor-rich solutions, electrical protection components, and other products used in automotive, industrial, energy, telecom, and construction industries. The company has 20 product categories including force sensors, tire management solutions, inverters & charges, and pressure sensors.The company’s next generation of products are designed to improve the efficiency of industrial pumps, fuel efficiency in ICE cars and energy efficiency in TVs, and facilitate usage of IoT devices.
Excel Cell Electronic, founded in 1981 is a manufacturer and supplier of electromechanical components and stamping products headquartered in Taiwan. The company offers electromechanical components including industrial control switches, stepping motors, terminal blocks, resettable fuses, and relays. Their stamping products include heat spreaders for BGA, high-precision electronic components, and lead frames of semiconductors for discrete devices / integrated circuit & photoelectric products. The company is ISO/TS 16949:2009, CNS15506: 2011, TOSHMS: 2007, ISO 14001, and ISO 9001-certified, and their products are used in various applications in optoelectronic, security systems, power energy, network, and communication industries.
LOVATO Electric S.p.A., founded in 1922 and based in Bergamo, Italy, is a manufacturer and designer of low-voltage electrical devices for industrial applications. The company offers a wide range of products such as Motor Protection circuit breakers, Contractors, electromechanical starters and relays, variable speed drives, and soft starters among others. The company holds UNI ISO 45001: 2018, ISO 1400: 2015, and ISO 50001: 2018 certificates. The company’s laboratories are certified to conduct type testing under ACAE control to issue ACAE certifications which are recognized by the European Union and valid across the wold.
RKC Instrument has been continually growing for over half a century and strives to be a solution provider of measurement and control systems. RKC supplies quality products and professional engineering services quickly and efficiently. RKC specializes in everything from limit and multiloop controllers to heater break alarms and temperature sensors. RKC has a website in Chinese, English, and Japanese and has sales networks across the globe. Based on the management concept of “Realization of the highest quality,” RKC Instrument has obtained the accreditation of ISO9001, the international standard for quality management systems.
Chino, headquartered in Tokyo, Japan, is engaged in the manufacture and sale of measurement and control equipment and instrumentation work. The company was founded in 1936 as Chino Seisakusho. Chino operates in the area of "measurement, control, and monitoring" and contributes to the development of all industrial fields. Major products include recorders, regulators, temperature sensors, data loggers, radiation thermometers, thermal image measuring devices/thermal cameras, composition meters, moisture meters, thickness meters, thyristor regulators, and fuel cell evaluation and testing devices.
Wieland, established in 1910 and based in Bamberg, Germany, is a manufacturer and supplier of electrical connection technology. Their product range includes pluggable connections for seamless plug-and-play electrical device connections, insulated connectors that provide electrical insulation in device connections, cable glands for safeguarding cables and ensuring a watertight seal, terminal blocks used for connecting electrical wires, and contact systems facilitating connections between electrical components. Wieland's products find applications in diverse industries, such as building construction, electrical engineering, and automation.
Fujitsu Component Limited was founded in Japan jointly by Fujitsu Limited and Takamizawa Electric Co. Ltd in 1995 which is a global manufacturer and seller of switching devices (relays) and Human interface devices such as keyboards, thermal printers, touch panels and switches. Their relay portfolio consists of relays for signal, power and automobiles applications. In addition they also manufacture eco friendly relay products. Fujitsu has establish several global support centers worldwide to ensure uninterrupted service. The group has adopted an environment philosophy which states that they will adhere to the corporate activities while improving their coexistence with the environment.
Shimaden Co., Ltd. is a manufacturer of industrial temperature and humidity control equipment founded in 1953 and based in Tokyo, Japan. The company manufactures a wide range of products for monitoring and controlling environmental factors. Its products include various sensor converters for humidity, digital or analog flow rate controllers, and thyristor power regulators for controlling isothermal tanks. These products are mainly used by clients in the food and beverage, chemical processing, and metal fabrication sectors. The company also offers control and data acquisition software for customers needing additional support.
Omron Corporation, started in 1933 and headquartered in Kyoto, Japan, is a manufacturer of automation components, equipment, and systems, and it developed the first contactless proximity switch in 1960. It has four domains, including industrial automation, electronic components, healthcare, and social systems, and it provides products and services in around 120 countries and regions. Some of its products include microsensing devices, access control systems, industrial robots, surveillance cameras, and blood pressure monitors. In 1971, it developed the first online cash machine, and in 1972, it established Japan’s first welfare factory.
Rockwell Automation, Inc. was founded in 1903 and is headquartered in Milwakee, WI. Rockwell Automation provides industrial automation and digital transformation solutions around the world. Rockwell Automation operates through their intelligent devices, software & control, and lifecycle services segments with both hardware and software products and services. The Intelligent Devices segment offers drives, motion, safety, sensing, industrial components, and configured-to-order products. The Software & Control segment provides control and visualization software and hardware, information software, and network and security infrastructure solutions. The Lifecycle Services segment provides consulting, professional services and solutions, and connected and maintenance services through independent distributors.
Number of Employees
Newly Established Company
Company with a History
*Including some distributors, etc.
*Including some distributors, etc.
Country | Number of Companies | Share (%) |
---|---|---|
Japan | 5 | 55.6% |
United States of America | 1 | 11.1% |
Taiwan | 1 | 11.1% |
Italy | 1 | 11.1% |
Germany | 1 | 11.1% |
45 products are listed.
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