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This section provides an overview for overcurrent relays as well as their applications and principles. Also, please take a look at the list of 20 overcurrent relay manufacturers and their company rankings. Here are the top-ranked overcurrent relay companies as of December, 2024: 1.AMADA CO., LTD., 2.SELCO USA, INC, 3.E-T-A Control Instruments.
Table of Contents
An overcurrent relay is a device that detects excessive currents in power systems, helping to prevent potential damage.
Within power systems managed by electric power companies, the permissible current levels are determined by generator capacity and the dimensions of transmission and distribution lines. Exceeding these levels can cause significant Joule heating, risking damage to transmission lines or generators. Overcurrent relays are essential for detecting currents that surpass these threshold values and preventing such hazards.
The overcurrent relay is identified by the number 51 in control apparatus schemes and is represented by the same number in electrical circuit diagrams.
Overcurrent relays are crucial in high-voltage or high-power applications, where their absence could lead to dangerous overcurrent incidents. Electric power transmission and distribution companies install overcurrent relays alongside circuit breakers to segment systems. Similarly, buildings, shopping centers, and factories, particularly those with high-voltage power installations, typically employ overcurrent relays.
However, the use of overcurrent relays in low-voltage applications is rare, as overcurrent protection can be provided by circuit breakers.
Overcurrent relays utilize instrument current transformers (CTs) to detect overcurrent conditions.
Due to the high currents and voltages involved upstream of the distribution system, direct measurement by overcurrent relays would be impractical and costly. Instead, instrument CTs scale down the current to manageable levels, typically to a range of 0 to 1 A or 0 to 5 A, which can then be safely monitored by the relay.
The overcurrent relay processes this scaled-down current and activates an alert or breaker trip if the current exceeds preset limits. Overcurrent relays are often paired with high-voltage or special high-voltage circuit breakers to immediately disconnect power upon detecting an overcurrent.
The static type, which operates under electronic control, is now predominant. Some models do not require a separate power supply, offering a characteristic curve similar to inductive types.
This design relies on the interaction between eddy currents in the iron core and a rotating disc, producing a magnetic field that triggers operation. While the induction disk type was once common for protective relays, it has largely been replaced by static types due to susceptibility to errors from environmental and internal factors, such as temperature fluctuations, vibrations, and component aging.
The mechanisms for triggering the relay to act are categorized into three methods: current trip, voltage trip, and capacitor trip.
This method employs an electric current to activate the trip coil of a vacuum circuit breaker, commonly used in smaller power installations.
Utilizing voltage to activate the trip coil, this method is preferred in large-scale installations. A DC power supply with a backup battery ensures reliable operation, even during outages, but increases the system's cost.
A variant of the voltage trip method, the capacitor trip method operates without a DC power supply. A built-in capacitor allows for operation during power failures, though its limited charge capacity restricts the number of uses.
*Including some distributors, etc.
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Mors Smitt Technologies Inc. stands as a manufacturer and supplier of components for the railway and industrial sectors, founded in 1851 and headquartered in Ede, Gelderland. Its portfolio includes relays, safety-critical electronics like circuit breakers and sensors, and precise measuring and control solutions such as data loggers and controllers. Notably, its offerings extend to panel indicators like digital displays and warning lights, as well as test equipment such as insulation testers and relay testers. With subsidiaries in the UK, Germany, and the US, Mors Smitt is a pivotal player in delivering solutions for signaling, safety, and control in critical applications.
E-T-A Control Instruments is a manufacturer of circuit breakers for equipment protection, circuit protectors, and more, established in 1976 and headquartered in Altdorf, Switzerland. The company delivers thermal overcurrent circuit breakers and high-performance circuit breakers. It also offers solid-state relays, remote power controllers, and time relays. These products protect against the hazardous effects of overcurrent and short circuits. The company serves the transport, production, telecommunications, medical, and equipment technology industries, and holds certifications including ISO 9001, ISO 14001, and ISO 50001.
Schweitzer Engineering Laboratory, established in 1982, is a manufacturer of power systems protection based in Washington, USA. The company provides cutting-edge products and services that enhance the efficiency and security of electrical power systems. The company offers many products, including protective relays, communication devices, automation controllers, and software solutions. The advantage of the company's products is its robustness, which can withstand harsh environmental conditions, making it suitable for deployment in diverse settings, from substations to remote installations.
Meiden Europe is a German manufacturer of electrical equipment and systems established in 1996 as a wholly-owned subsidiary of Japan’s Meidensha Corporation, which has been in operation since 1897. Headquartered in Unterschleissheim, Bavaria, the company produces various electrical equipment including surge arresters, inverters, and motors, as well as electrical systems for railway power supply and substation automation. These are utilized in a wide range of industrial processes, such as in power transmission or distribution, water treatment and robotics. Meiden Europe has sales offices and facilities across the European Union, including in France, Switzerland, Slovakia, Austria, and the United Kingdom.
DOLD is a manufacturer of safety and interlocking devices, founded in 1928, with headquarters located in Furtwangen, Germany. Their product range includes safety relays, electronic housings, safety switches, as well as solenoid interlocks, and key transfer systems. These devices play a crucial role in ensuring secure operations, controlling access, and protecting workers and equipment during manufacturing processes. DOLD is certified according to DIN EN ISO 9001:2015 for quality management and quality systems.
ENTES Elektronik, established in 1980 and headquartered in Istanbul, Turkey with additional offices in Germany, Greece, and India, is a manufacturer of power and energy management solutions used in industrial applications. The company’s production line is categorized into power quality and energy, electrical measurement, power factor correction, energy management hardware and software, and current transformers. It also offers protection & control products such as phase failure relays, liquid level controllers, overcurrent monitoring relays, daylight switches, and control & isolating transformers.
ORION ITALIA s.r.l, headquartered in Piacenza, Italy, is a specialized manufacturer of protection relays and temperature controllers for industrial applications and utilities. The company offers a line of protection and control products, including protections for feeders, motors, voltage, and frequency. It also produces temperature monitoring and control systems designed to prevent and mitigate transformer failures. The company's international standard is evident through the ISO 9001 certification of its commercial and logistics departments.
NR Electric Co., Ltd., a subsidiary of NARI Technology Development Limited Co., established in 1995 and headquartered in Nanjing, Jiangsu, China, is a manufacturer of power system protection and control solutions. The company’s product portfolio comprises phasor measurement, power grid monitoring & controls, digital substations, stability control systems, and accessories such as test blocks, interposing relay sets, operating relays, and auxiliary relay sets. These products are used in the power industry to offer various solutions including power generation, transmission systems, distribution networks, and industrial consumers in the power industry.
SEG Electronics GmbH is a developer and manufacturer of intelligent protection devices for power generation and distribution, founded in 1969 and headquartered in Kempen, Germany. The company’s product line includes grid and protection relays, general protection devices, enhanced transformer differential protection, earth fault voltage relays, and interface adapters. It also offers directional feeder protection, main decoupling relays, and mechanical flag indicators. The company holds CE, UL, CSA, and EAC certifications, with operations in multiple countries worldwide. Its products are utilized for the electrical protection of generators, transformers, motors, cables, and overhead lines.
AMADA, founded in 1948 and based in Kanagawa, Japan, is a manufacturer of metalworking machines and equipment. The company offers a comprehensive range of solutions, including sheet metal machinery, cutting machines, grinding machines, stamping presses, and micro welding equipment. Additionally, it provides software, peripheral equipment, tooling, and maintenance. Its offerings are instrumental in improving productivity, precision, and efficiency in metalworking processes, benefiting the manufacturing and production sectors. It operates with a network of 90 subsidiaries and affiliated companies, all led by AMADA Co., Ltd.
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.
Selec Controls, founded in Navi Mumbai, Maharashtra, in 2000 is a manufacturer of Electrical Measurements and Protection, Meters, and, Automatic Power factor controllers. The company's product portfolio includes Indicators and Controllers, Digital Timers, Temperature Controllers, Speed Monitoring Relays and Humidity and Temperature Controllers. The company serves industries such as Oil and Gas, Aerospace and Defense, Automotive and Transportation, Construction, and Power Generation. The company has 200+ distributor network and global sales offices.
Established in 1992, Fanox is a famous manufacturer and supplier of safe and dependable protection relays headquartered in Pais Vasco, Spain. The company's concept is centered around research and innovation, with a significant allocation of resources towards design engineering. One of the intentions of the energy transition in the power business is to promote and integrate Renewable Energies. This phenomenon results in the developing of a more adaptable and distributed electrical infrastructure, necessitating a digital transformation of the business to manage it effectively.
Fuji Electric Equipment Control was established in 2008 in Saitama-ken, Japan is a manufacturer of power distribution and control equipment. The company boasts an extensive and diversified product portfolio including motor controls, MV distributors, energy control equipment, LV distributors, and industrial control relays. These products find applications in construction as magnetic contactors, automotive as manual motor starters, home appliances as air circuit breakers, health care devices as sensors and switches, and in environmental management for quality assurance and protection of high-voltage electric power and management of low-voltage consumption rate.
DEIF A/S, founded in 1933 and headquartered in Skive, Denmark, is a supplier of safe power control products for decentralized power generation on land and sea. The company offers products such as single genset controllers, protection relays, HMI control panels, and pitch battery chargers. The company's products are used in land power, whitepapers, webinars, wind power, and marine sectors. It has ISO 9001:2015 and ISO 14001:2015 quality management certifications and also offers training, repair, and consultancy services.
Grid Solutions, established in 1892, is a global producer and distributor of GE Renewable Energy solutions headquartered in Boulogne-Billancourt, France. The company is a part of GE Vernova with over 12,000 employees offering equipment, systems, and services to power utilities and industries, ensuring efficient power delivery from generation to consumers. These include Power Electronics, High Voltage Equipment, Automation & Protection, Software Solutions, and Projects & Services. Addressing the challenges of the energy transition, Grid Solutions provides safe integration of renewable and distributed energy into the grid using HV/MV equipment, gas-insulated substations, and more.
Ranking as of December 2024
Derivation Method| Rank | Company | Click Share |
|---|---|---|
| 1 | E-T-A Control Instruments |
15.8%
|
| 2 | Selec Controls |
15.8%
|
| 3 | AMADA CO., LTD. |
15.8%
|
| 4 | SELCO USA, INC |
10.5%
|
| 5 | NR Electric Co., Ltd. |
10.5%
|
| 6 | ENTES |
5.3%
|
| 7 | Fanox |
5.3%
|
| 8 | ORION ITALIA s.r.l |
5.3%
|
| 9 | Schweitzer Engineering Laboratory |
5.3%
|
| 10 | Meiden Europe |
5.3%
|
Derivation Method
The ranking is calculated based on the click share within the overcurrent relay page as of December 2024. 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.Number of Employees
Newly Established Company
Company with a History
*Including some distributors, etc.
*Including some distributors, etc.
| Country | Number of Companies | Share (%) |
|---|---|---|
|
United States of America
|
4 | 26.7% |
|
Germany
|
2 | 13.3% |
|
India
|
2 | 13.3% |
|
Denmark
|
2 | 13.3% |
Japan
|
1 | 6.7% |
|
Turkey
|
1 | 6.7% |
|
Italy
|
1 | 6.7% |
|
China
|
1 | 6.7% |
|
Spain
|
1 | 6.7% |
11 products found
11 products
Tokyo Densetsu Service Co., Ltd.
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This is a device installed at power generation and substations that protects the power system by isolating and localizing (preventing the spread of...
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IED is an abbreviation for Intelligent Electronic Device, and it is a general-purpose device that integrates multifunctional and flexible protectio...
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IED is an abbreviation for Intelligent Electronic Device, and it is a general-purpose device that integrates multifunctional and flexible protectio...
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IED is an abbreviation for Intelligent Electronic Device, and it is a general-purpose device that integrates multifunctional and flexible protectio...
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■Protective device This is a microprocessor type device that quickly and accurately detects failures in power system transmission lines and distrib...
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■Protective device This is a microprocessor type device that quickly and accurately detects failures in power system transmission lines and distrib...
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■Protective device This is a microprocessor type device that quickly and accurately detects failures in power system transmission lines and distrib...
Hikari Shoko Co., Ltd.
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Protects high voltage circuits from overcurrent caused by short circuits and overloads. ■Features ・Four time-limiting characteristics Protection ...
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Protects high voltage circuits from overcurrent caused by short circuits and overloads. ■Features ・Four time-limiting characteristics Protection ...
Denkosha Co., Ltd.
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■Summary A protective relay is a device that detects faults such as short circuits and ground faults that occur in power lines and power equipment ...
