This section provides an overview for voltage relays as well as their applications and principles. Also, please take a look at the list of 31 voltage relay manufacturers and their company rankings.
Table of Contents
A voltage relay is a relay device that transmits electric power and detects abnormalities, especially those related to voltage. Generally, it is used for voltages above high voltage.
Two types of voltage relays are often used: overvoltage relays and undervoltage relays. An overvoltage relay is called an OVR (=over volt relay) and an undervoltage relay is called an UVR (under voltage relay). For ground faults, a device called an OVGR (ground fault overvoltage relay) may also be used.
Voltage relays are used in factories, high-rise buildings, elevators, and stations. These facilities often have generators for high-voltage supply, and they are used to provide protective coordination between the generator and the commercial power supply.
Most distribution networks that transmit power to ordinary homes are equipped with higher-level protection functions, such as automatic reclosing. The section separated by an air switch is often posted with a voltage relay for automatic reclosing.
Although the characteristics of voltage relay vary depending on the uses of the relay, there are two types of voltage relay. One is used to monitor and control constant current and constant voltage transmission, such as OVR. The other is used to avoid zero power phase due to ground fault accidents or sudden transformations caused by trouble, such as OVGR.
A ground fault is a situation in which excessive current is transmitted to the ground where electricity is not normally flowing. The excess voltage is controlled by OVGRs to prevent dangerous discharges. For this reason, these devices are also called protective relays.
While OVRs are used as stand-alone devices, OVGRs are used in combination with DGRs to control the irregular current voltage caused by force majeure. This is to prevent power transmission and transmission voltage fluctuations and hazards due to earthquakes and weather conditions.
In addition, there is a type of voltage relay called UVR (undervoltage relay) that compensates for and controls the voltage that has been reduced. This type of device maintains constant current and constant voltage transmission by compensating the voltage in the opposite direction. It also sends a command signal to a private generator to start switching.
As mentioned earlier, there are different types of voltage relays, each with its own role.
Overvoltage relays are used at the receiving points of large plants on the consumer side and on the secondary side of generators on the transmission side. The main cause of overvoltage is trouble on the transmission side. If there is negligence on the customer side, it is due to the power factor of the phase advance caused by the constant input of capacitors, etc. On the transmission side, the customer's equipment is broken. The undervoltage relay is used on the transmission side to protect the customer's equipment from damage and on the customer's side to protect the equipment in the customer's house.
Undervoltage relays are used to activate backup power supplies on both the customer and transmission sides. Backup power sources often refer to emergency generators and also include emergency lighting. They are also used to protect inverters, as undervoltage or missing phases in inverters can lead to failures.
Ground-fault over-voltage relays are used for ground-fault detection. However, ground-fault overvoltage relays are rarely used alone. The normal voltage between earth and ground is generally 1/√3 times the line-to-line voltage when three-phase AC is used. In the case of a complete ground fault on one line in an ungrounded system, the voltage to ground is 0 V on the ground fault phase and equal to the line-to-line voltage on the healthy phase, resulting in an overvoltage on the healthy phase. However, if a ground fault occurs on the primary side, the ground-to-ground overvoltage is also generated. Therefore, a ground-fault overvoltage relay is used in conjunction with a directional relay or a similar device.
Voltage relays are those that operate at the specified voltage. Undervoltage relays and overvoltage relays are also a type of voltage relay. Considering 84 as one that operates at normal voltage, uses of this type of relay include use in parallel operation of generators in combination with synchronous speed switches.
Electrical equipment is assigned a symbol called a control appliance number. For example, a breaker is called 52, or 52 is written on the drawing. This has the advantage that the function can be understood only by a list of numbers on the drawing, and even equipment with long names can be shortened and uttered.
The above voltage relay is also assigned a control device number, 84, when referring simply to a voltage relay. When referring to an overvoltage relay, the control device number is 59. The control device number for an undervoltage relay is 27. The control device number for an earth fault overvoltage relay is 64.
*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.
ABB E-mobility provides electric vehicle charging solutions for customers around the globe. ABB E-mobility offers DC fast chargers as well as AC chargers with focus on reliability and uptime. Since 2010, ABB E-mobility has sold over 50,000 DC fast chargers and over 1 million total AC chargers. ABB E-mobility offers home single and multi-charge units, retail, workplace, and hospitality charge units, electric vehicle fleet sales, as well as public transportation. Additionally, numerous digital solutions and software services are available.
Omron Automation was originally established in 1933. Omron Automation is a producer and manufacturer for industrial automation solutions including robotics, sensing, motion, logic, and safety. Industries include automotive automation, electric vehicle manufacturing, food and beverage packaging, semiconductor and manufacturing electronics, life sciences automation, logistics & warehouse automation, machine tool, oil and gas, water and wastewater, entertainment, security and detention, and other industries. Some of Omron Automation’s product categories include machine automated controllers, RFID solutions, safety laser scanners, safety outputs, smart cameras, vision sensors, machine vision software, servo systems, articulated robots, parallel robots, SCARA robots, photoelectric sensors, and rotary encoders along with many software-based solutions.
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.
Accele Electronics, Inc. is based in Santa Fe Springs, California. Accele has a 30 year history as a manufacturer and distributor of automotive technology solutions, also offering services such as, installation and support throughout its 30+ year history. Example products include LCD monitors, headrest monitors, mirror monitors, drive and park sensors, video recording and camera kits and accessories, A/V switchers, RV camera systems, cables, lighting, HUD, security systems, fuses and circuits, relays, bus and coach amenities, as well as comfort and convenience items.
Based in Bayville, NY, SAE Manufacturing Specialties Corp. is an ISO-certified supplier and manufacturer of industrial equipment, chemicals, components, ordinance, electronics, and systems for industries ranging from aerospace to high tech to law enforcement. Examples of product offerings include raw materials, chemicals, and lubricants for industrial purposes to finished products such as security helmets for law enforcement, and military ordnances. SAE also provides research and development as well as technical support for other companies in similar industries.
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.
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.
WIN SOURCE is a customer-focused online store serving a wide variety of markets industries ranging from consumer to automotive to medical, industrial, and aerospace. WS specializes on size and speed, offering a catalog of over 1 million SKUS that can be shipped within 24 hours around the world. Offerings include an extensive array of semiconductor components, audio products, cable assemblies, racks, and battery products. WIN SOURCE is AS9120B, ISO9001, ISO14001, and ISO45001 certified and is a member of the anti-counterfeiting organization, ERAI.
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.
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.
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.
Pilz is headquartered in Ostfildern, Germany. Pilz designs components, systems, and services to assist industrial plant and machinery customers globally. Customers include many industries such as metals, pharmaceutical, food, presses, and robotics. Pilz serves customers through 4 venues: products and industries, services, support, and training. Products and services include everything from sensor technology and small controllers to robotics to software and operation monitoring. Services include machinery and workplace safety and international compliance. Support is offered 24/7. Training is available through courses and qualification programs.
Eaton Corporation plc was founded in 1911 and is based in Dublin, Ireland. Eaton operates as a global power management company, providing electrical components, industrial components, power distribution and assemblies as well as industrial applications. The company’s vehicles segment also offers transmissions, hybrid power systems, and fuel vapor components for the vehicle industry. The company’s eMobility segment offerings include voltage inverters, power distribution systems, and commercial vehicle hybrid systems. The company also provides engineering and repair services.
Saddle Brook Controls is a division of Ribble Engineering, which was founded in 1933 in Saddle Brook, New Jersey. Saddle Brook Controls is a manufacture as well as a designer, distributor, and support service provider of automation solutions for factory automation. Product groups include PLCs, controllers, Remote IO devices, HMIs, industrial computers, machine vision and inspection machines, motion devices, drives, motor controls, enclosures, circuit breakers, safety products, sensing and control products, power supplies, and UPS.
Auburn Armature was founded in 1946 and headquartered in Auburn, New York. Auburn Armature is a distributor of electrical products and was recently purchased by Power-Flo Technologies of New Hyde Park, New York. Services that Auburn Armature provide include training, testing, rebuilding, repair, troubleshooting, and training. Parts that Auburn Armature specialize in include automation systems, AC and DC drives, motor controls, motors, motion controls, connectors, wire, boxes, cables, sensors, relays, transformers, panels, struts, terminal blocks, lighting supplies, and conduits.
American Distributors LLC (ADI) was founded in 1983 and has corporate offices in Randolph, New Jersey. ADI manufactures and distributes products for medical diagnostics, industrial usage, maritime usage, aerospace, and military. ADI is ISO 9001:2015 certified. ADI’s product line includes capacitors, chip resistors, coils, chocks, connectors, crystals, diodes, fans, filters, fuses, hardware & accessories, heat shrinkable tubing, inductors, integrated circuits, lamps & lighting development, networks equipment, Parylene coating, relays, resistors, semiconductors, IC sockets & terminals, switches, transistors, and wire & cable.
HoverLabs has roots dating back to 1963 and is headquartered in Haryana, India. The company is a laboratory supplies manufacturer, exporting to over 110 countries. The company provides extensive R&D for designing, manufacturing, and packaging supplies. The company also provides customized product development, OEM support, and project management assistance. The company’s products include educational equipment, analytical lab equipment, engineering lab equipment, medical lab equipment, and other products used in the medical as well as scientific industries.
VTEK Elektrik is a manufacturer and distributor of electrical systems and components based in Istanbul, Turkey. The company was established in 1985 and has a specialized product portfolio including transformers, and protection relays. miniature relays, cam switches, and converters. These primarily supply clients in the power generation, renewable energy, and industrial automation industries. From its state-of-the-art facility, the company also offers a range of services, such as commissioning, quality control, calibration, and prototyping. VTEK Elektrik is ISO 9001:2015 certified and has an international presence with distributors in different countries.
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.
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