This section provides an overview for control relays as well as their applications and principles. Also, please take a look at the list of 46 control relay manufacturers and their company rankings. Here are the top-ranked control relay companies as of June, 2023: 1.Industrial Electric Machinery, 2.OMRON Industrial Automation, 3.Schneider Electric.
Table of Contents
A control relay is a component that receives an electrical signal and outputs a digital signal to control a machine.
The name "control relay" is derived from the image of a baton relay, in which one input originates and affects another output.
Control relays are one of the most widely used components in industry and everyday life. The following are examples of control relay applications:
Mainly used to pass input signals from sensors or push buttons to another device. Because they are used in places where control is being performed, they are used not only in industrial equipment but also in electrical appliances.
If the control system is complex, reproducing it with control relays requires several hundred points and is complicated, so PLCs and PCs are used to output calculations. However, if only a few relays are used, it is cheaper and easier to use electromagnetic relays for control.
There are two types of control relay, one with a contact point and the other without a contact point.
Contact relays are relays that mechanically operate their contacts to output a contact signal. They are also called mechanical relays because of their operating principle. It consists of electromagnetic coils and contacts.
When the relay receives an input voltage signal, the internal electromagnetic coil is excited. The excited electromagnetic coil acts as an electromagnet and operates the movable contact, which moves together with the movable iron strip. The movable contact makes contact or pulls away from the fixed contact and outputs an electrical contact signal.
When the input voltage is removed, the contacts return to their positions by being pushed back by an internal return spring. The electromagnetic coil consists of copper wire wound around an iron core and coated with varnish for insulation.
In addition, silver alloys or gold are used on the contacts to reduce electrical resistance. They are generally protected by a casing to prevent easy human contact.
A contactless relay is a component that uses a semiconductor to output a contact signal without physically operating the contact. Because of their operating principle, they are also called solid-state relays. The main component of a solid-state relay is a photocoupler.
First, when a voltage is applied to the input terminal, the LED inside the photocoupler is excited, and the LED generates light that is directed to an internal light-receiving element. The light-receiving element uses a phototransistor that conducts by light and thus outputs a contact signal by the light from the LED.
The characteristic of a contactless relay is that there is no mechanical contact, as in the case of a relay with a contact point, so there is no metal wear due to opening and closing operations. The transmission speed is also high, making it suitable for high-speed and high-frequency opening and closing. Other features include good insulation, no need for noise suppression, easy miniaturization, and no operating noise.
However, a drawback is that semiconductor elements are quickly damaged when voltages and currents exceeding their ratings are applied. They are vulnerable to heat and require adequate heat dissipation measures. They are also more expensive than contact relays.
Control relays have the following three types of contacts:
The A-contact is a contact that is open when no signal is input to the input terminal and conducts when a signal is input. It is also called a normally open contact or a make contact. It is the most common type of contact that provides signal isolation only.
The B-contact is a contact that conducts when no signal is input to the input terminal and opens when a signal is input. It is also called a normally closed contact or a break contact.
It is characterized by the opposite action of the A-contact and can invert and output the input signal. It is often used in interlock circuits and fault interrupting circuits.
The C-contact is a three-terminal contact that combines an A-contact and a B-contact. It has three terminals: a common terminal, an A-contact terminal, and a B-contact terminal. When no signal is input to the input terminal, the common-b contact terminal is conducting and the common-a contact terminal is open.
When a signal is input to the input terminal, the common terminal-b contact terminal is open and the common A-contact terminal is conducting. It is used for circuits that switch between forward and reverse rotation. Another feature of the C-contact is that it is applicable only to contact relays.
*Including some distributors, etc.
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NOARK is based in Pomona, California, and is a global manufacturer of low-voltage electrical components for industrial applications. NOARK specializes in motor controls and protection for original equipment and manufacturers with products covered by five-year limited warranties. NOARK parts are used in numerous solutions such as HVAC and refrigeration, industrial food equipment, panel builders, digital storage, and engine generators. NOARK’s main product lines include low-voltage power circuit breakers, molded case circuit breakers, miniature circuit breakers, overload relays, and circuit control devices.
Amperite Co., through OlympicControls Corp., was founded in 1968 with roots going back to 1922. The company serves military and industrial market segments with motor controls, circuit controls, alarms, and other systems. The company offers four specific, focused business units that maintain identities in separate end-user applications: Amperite Co., OlympicControls Relays, T-Bar Relays, switches, and Fuel Pumps. Amperite manufactures time delay relays, flashers, and controlling devices. OlympicControls offers customized products manufactured to customer specifications. T-Bar Relays serves OEMs and customers such as Raytheon and Learjet. Fuel Pumps serve military and heavy-duty trucks.
Motor Protection Electronics, Inc. was founded in 1983 and is located in Apopka, Florida. The company is a manufacturer and designer of industrial controls for several industries including water and wastewater industries to customers around the United States through its distributors. Since its founding, the company has designed and manufactured all parts at its company headquarters in Apopka, Florida. The company’s 10 product segments include phase and voltage monitors, alternators, time delay relays, and intrinsically safe controls.
Wisconsin Oven Corporation has operated since 1973 and is located in East Troy, Wisconsin. Wisconsin Oven designs, engineers, and manufactures industrial ovens and other heating equipment for numerous applications including heat treating, powder coating, paper pulp drying, finishing, drying, and curing in the aerospace, automotive, composite, energy, finishing, foundry, heat treating, annealing, military, and pharmaceutical industries. Types of ovens and equipment include custom and standard batch ovens, conveyor ovens, pollution control equipment, and walk-in ovens.
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.
L.A. Woolley Electric, Inc. (L.A. Woolley) was founded in Buffalo, New York in 1916 as a supply distributor to serve the industrial and commercial marketplace. The company offers products from such manufacturers as Acme, Mersen, Pass & Seymor, and Wago. The company specializes in control and panel board products, transformers, terminal blocks, wiring accessories, as well as hazardous location products. The company's in-house sales team also support customers in selecting, ordering, and receiving the correct order.
PLC Hardware (PLCH) was founded in 1993 and operates out of Owings Mills, Maryland. PLCH is an independent distributor of used and surplus industrial automation and networking equipment. PLCH offers a 1-year warranty on all products and ships globally. PLCH’s emphasis is on hardware and distributes hardware from such brands as Cisco, HP Networking, Rockwell Automation and Siemens. A few of the many categories of hardware include application networking products, cables, optical networking systems, routers, switches, rack servers, content delivery devices, as well as HVAC controllers, and safety integrated systems.
Industrial Electric Machinery, also known as IEM, was originally founded in 1988 as Northwest Motor Service. IEM serves industrial customers with products and services including motors, relays, transformers, UPS batteries, and more. IEM offers 4 primary product categories: Controls such as low voltage VFDs and transformers, gearboxes & couplings, motors, and power distribution including MCCs and automatic transfer switches. IEM also offers field service including 24/7 availability for troubleshooting, analysis, calibration, field testing, and repairs. Additional services such as training courses and warehousing of spare equipment is also available.
Struthers-Dunn is headquartered in Timmonsville, South Carolina, and was established in 1923, making it one of the oldest relay manufacturers in the world. The company’s relays and related electrical components are utilized in traffic signals, power generation, factory automation, construction, and water treatment applications. The company’s product lines primarily consist of relays such as general purpose, motor, timer, and sequencing relays. Other products include accessories and special-purpose relays for super high voltage applications such as gas turbine power plants.
Avatar Instruments is a manufacturer of industrial power controllers and temperature controllers for electric heater control, founded in 1990 and located in Lewes, Delaware. They specialize in SCR power controllers, which utilize silicon-controlled rectifiers to control the flow of electric power. They also produce custom temperature control solutions and control panels. Avatar Instruments has received CE certification on its A Series SCR units and is the first manufacturer to offer a 5-year warranty on SCR power controllers.
CIT Relay & Switch is based in Rogers, Minnesota, and is a manufacturer of RoHS-compliant electromechanical relays and switches with the ability to offer integrated solutions for individual customers’ design needs. CIT’s relays are commonly used in automobiles and low-voltage operations. CIT’s switch catalog includes varieties such as surface mount, panel mount, tactile, pushbutton, and more. CIT has a lab for a new design, validation product testing, IQC, failure analysis, and material testing. IQC ensures documented reliability by testing contact material, resistance, dielectric strength, and other parameters. CIT also provides engineering and application support for materials and processes.
Syscom Tech is headquartered in Moorestown, New Jersey. Syscom Tech is a manufacturer of electronics for numerous industries including automotive, chemical, computer, aerospace, medical, industrial, security, and telecommunications. Syscom’s facilities are AS9100/ISO 9001 certified. Syscom Tech’s product offerings include PCB design and assembly, cable assembly and wire harness arrangement, as well as electro-mechanical assembly. Additional services for electro-mechanical assembly include box build assembly, turnkey PCB assembly, and other high quality PCB assembly solutions.
Dietz Electric was founded in 1974 and is based in Milwaukee, Wisconsin. Dietz Electric is a broad-line stocking distributor offering electric motors, drives, and power transmission products. Dietz Electric also offers customization options to test, manufacture, modify, and repair all product offerings. Product offerings include electric motors, hazardous locations motors, custom electric motors, variable frequency drives, motor controls, power transmission solutions, and specialty items such as purge systems, Uras vibrators, disc brakes, transformers, and AC line reactors.
Twittlebit.com is located in Lexington, Kentucky. Twittlebit is a distributor of industrial equipment and components divided into 8 sub-stores including: sensors, HMI & PLC, visual & audio , panel components, and pneumatic & vacuum. The company offers next day delivery to Kentucky and neighboring states, and 2-to-3-day delivery to most other states of in-stock products. The company offers in-stock selection of many top brands such as Autonics, EEControls, Panasonic, and Cembre. The company can also in-source many hard to find products directly from Japan from companies such as IDEC, Canon, Omron, and Fuji Electric in 7-to-10-days.
Hybrid Electronics is a global distribution specialist of electronic components, with access to over 50 million unique components. Among the markets HE serves are the aerospace, automotive, communications, defense, industrial, medical, national security, and test & measurement industries. In addition to components, HE also provides quality and compliance testing, counterfeit detection, upscreening, and other forms of quality control. Examples of component subtypes that HE offers include ICs, batteries, capacitors, semiconductor products, sensors, circuit protection, interconnectors, filters, optoelectronics, relays, switches, power supplies, and cables and cable assemblies.
Shamrock Controls is a division of Burns Controls Company, an industrial distributor of hydraulic, pneumatic, and automation products. Burns Controls Company was established in 1971 in Dallas Texas. Shamrock Controls is a global distributor of IEC electrical motor controls and factor automation solutions. Shamrock Controls product listings include contractors, overload relays, DP contractors, relays, push buttons, pilot lights, control stations, motor starters, circuit breakers, disconnect switches, cam switches, power supplies, terminal blocks, cable glands, lock nuts, din rails, ducts, wire accessories, and various pneumatic components.
Penn Radiant Products was started in 1963 and is currently headquartered in Pittsburgh, Pennsylvania. The company is a distributor of heating and cooling systems and components to HVAC and other markets across Pennsylvania through Illinois. The company operates in four market segments: Gas Heating, Electric Heating, Parts, and Cooling. The gas Heating segment includes gas-fired and diesel-fired heaters, thaw sheds, ceramic heaters, and flame torches. The Electric Heating segment includes space heaters, quartz heaters, and others. The Cooling segment includes spot coolers, drum fans, and AC units.
AutomationDirect.com was founded in 1994 to provide solutions for the industrial automation market and has been growing its list of offerings ever since. AutomationDirects’ extensive catalog includes individual components such as cables, various controls, I/O devices, relays, gauges, fittings, and sensors to complete systems. Many parts and devices, especially PLC units are customizable. AutomationDirect.com also provides support via video instructions, online manuals, a learning library, an active community forum to further assist customers.
Schneider Electric S.E. is headquartered in Rueil-Malmaison, France, and has been operating since 1836. Schneider Electric provides a number of products and services including electrical car charging, energy management software, surge protection devices, load banks, servers and HMIs, valve and valve actuators, feeder automation, grid automation, and SCADA software products, data center cooling and software, home automation and security, light switches, motion control and robotics, signaling units, solar and energy storage, RFID systems, as well as other hardware, services, and software.
MOD-TRONIC Instruments Limited was established in 1972 in Brampton, Ontario, Canada. MTis a distributor of industrial sensors, transducers, heaters, controls, and instrumentation, primarily made in the USA as well as Japan, Switzerland, and Germany. MT’s customers are primarily in the aerospace, building automation, manufacturing, medical, military, oil and gas, and water treatment industries but also serves individuals. MT offers an above industry standard 5-year warranty and technical support on every product sold.
Wieland Electric is headquartered in Hamberg Germany and was founded in 1910. Weiland Electric is a manufacturer of electrical connection and industrial automation products used in conveying, logistics, horticulture, lighting, machine building & safety, and energy industries. Wieland Electric’s product categories include active industrial products, passive industrial products, modular wiring systems, power distribution for electric vehicles, integrated lighting & building solutions, and indoor interconnect products such as metal fabrication, 3D printing for prototyping, electrical design, and box build fabrication.
OMEGA Engineering was originally begun in 1962 as a manufacturer of thermocouples and has grown to over 100,000 products for measurement and control of temperature, humidity, pressure, strain force, flow, level pH, and conductivity as well as customer service including data acquisition, electric heating, and custom-engineered products. Additionally, OMEGA offers tools to serve as reference for engineers around the world. OMEGA Engineering serves the aerospace, automotive, wireless, sanitary, test & measurement, process control, power monitoring, environmental, and laboratory markets.
METZ CONNEct was founded in 1976 in Blumberg, Germany. The company is a global manufacturer of electronics used in semiconductor, manufacturing, consumer electronics, and other industries. The company has 3 primary product lines: P-cabling, U-Contact, and C-Logline. P-Cabling provides cabling solutions for networks and includes DIN rail housing, patch panels, and fiber optic wall distributors and housings. U-Contact for connection technology includes PC board terminal blocks and board-to-board connectors. C-Logline for intelligent system components includes I/O components, energy controlling, and telecommunication products.
OMRON Industrial Automation is the UK branch of OMRON, originally founded in Japan in 1933. OMRON Industrial Automation serves food and beverage industry, panel board design, automotive manufacturing industries among others. OMRON Industrial Automation products categories include automation systems such as industrial PCs and human machine interfaces (HMI), safety such as safety switches and safety logic control systems, switching components such as solid state relays, motion & drives such as motion controllers, sensing such as photoelectric sensors, software, robotics, quality control & inspection systems, as well as control components including power supplies and digital panel indicators.
Dinkle Group was established in 1983 and is headquartered in Taipei, Taiwan. Dinkle is a multi-national, ISO 9001-certified manufacturer and distributor of electronics and equipment for industrial sectors such as factory automation, transportation, new energy, telematics, and equipment manufacturing. Dinkle has 4 product lines: terminal blocks, electronics & interface, electronic housings, and tools. Terminal blocks include PCB terminal blocks, barrier terminal blocks, and NEMA terminal blocks. Electronics & interface include interface modules, surge protection devices, and industrial relays. Electronic housings include enclosures for bus systems, DMEB component housing, and PCB carriers. Tools include drivers, marking systems, ferrules, and others.
Wenzhou DAQUAN Electric Co., Ltd was founded in 1996 in Wenzhou, China. The company is an electrical products manufacturer of relays, relay sockets, timers, meters, and related components to customers both in and outside of China and serves both home appliance customers as well as industrial customers in manufacturing and other industries. The company has 5 major product segments including relays, timers, meters, circuit breakers, and switches. The company also sells various tools, alarm devices, and product accessories.
Celduc Inc. through Celduc Transfo was founded in 1960 as a manufacturer of transformers. Celduc Inc. is based in, France. Celduc Inc. was officially created in 2020 and headquartered in Centerport, New York. Celduc creates electronics and customized products for industries including railway, plastic, packaging, medical, and electronics. Celduc’s main product lines include solid state relays, magnetic proximity sensors, reed relays & switches, and customized products. Customized products are versions of other products adapted for use in industries with special needs such as nuclear power, aircraft, and agriculture.
Ranking as of June 2023 in United States of AmericaDerivation Method
|1||Industrial Electric Machinery||13.3%|
|2||OMRON Industrial Automation||13.3%|
|4||Wieland Electric Inc.||6.7%|
|5||Wisconsin Oven Corp.||6.7%|
|8||Fuji Electric FA Components & Systems||6.7%|
|9||Wenzhou DAQUAN Electric||6.7%|
Ranking as of June 2023 GloballyDerivation Method
|1||Industrial Electric Machinery||6.3%|
|3||Wenzhou DAQUAN Electric||6.3%|
|4||Wisconsin Oven Corp.||6.3%|
|5||Fuji Electric FA Components & Systems||6.3%|
|8||OMRON Industrial Automation||6.3%|
|19||Shamrock Controls div. of Burns Controls Company||3.1%|
|20||Penn Radiant Products||3.1%|
|21||Wieland Electric Inc.||3.1%|
|22||NOARK Electric North America||3.1%|
Derivation MethodThe ranking is calculated based on the click share within the control relay page as of June 2023. Click share is defined as the total number of clicks for all companies during the period divided by the number of clicks for each company.
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