Ring Main Unit (RMU) for Smart Grids
Modernise your grid with the smart ring main unit (RMU)
The ring main unit is a compact, fully enclosed, factory-built cabinet designed for medium voltage (MV) power distribution. This switchgear unit is straightforward to replace, requires minimal maintenance, and offers high levels of protection. To cater to varied needs, RMUs come in different voltage options, making them suitable for both outdoor and indoor applications. At Schneider Electric, we bring advanced technology and innovation to your grid through our exclusive range of smart ring main units, ensuring safety and efficiency in upgrades.
Seamlessly integrated with the PowerLogic T300 remote terminal unit (RTU) and our innovative conditional monitoring sensors, the smart RMU is an innovative solution that makes it easier for you to answer the evolving challenges of electrical distribution. As an all-in-one solution, the smart RMU is easy to purchase, install and maintain, helping to reduce operational costs. Its robust design fits even the harshest environments.
A smart RMU is an advanced version of the traditional Ring Main Unit, designed for MV distribution networks. While a conventional RMU provides basic switching and protection functions, a smart RMU integrates digital technologies such as advanced analytics, remote monitoring, automated fault detection, and grid reconfiguration. It is typically equipped with sensors, communication modules, and remote terminal units (RTUs), enabling real-time data acquisition and integration with smart grid platforms.
Smart RMUs offer a range of digital functionalities, including:
• Remote control and monitoring via SCADA systems and RTUs like PowerLogic T300.
• Condition monitoring using thermal sensors, partial discharge sensors, and predictive analytics.
• Cybersecurity compliance with standards such as IEC 62351 and IEEE P1686.
• Automated fault isolation and power restoration, reducing outage times and improving SAIDI metrics.
• Integration with distributed energy resources (DERs) and support for grid decarbonisation and decentralisation.
Smart RMUs bring several advantages:
- Enhanced reliability through looped network configurations and advanced monitoring, protection, control and automation functions thanks to RTU usage.
- Reduced operational and maintenance costs due to predictive maintenance and fewer manual interventions.
- Improved energy efficiency and load management via advanced analytics available in RTU.
- Environmental sustainability, especially with SF6-free usage.
- Improve energy availability with a cost- and time-effective solution (SAIDI).
RM6
Learn more about our 2,000,000+ modules with installed MV ring main unit.
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FBX
Discover flexible installation in compact or extensible applications.
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Ringmaster
Find out more about our MV ring main units for outdoor applications.
PowerLogic T300
Discover a powerful Remote Terminal Unit (RTU) for feeder automation.
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Discover how digitisation, decarbonisation, and decentralisation are transforming the energy world.
How to Visualize, Operate & Safely Perform Cable Testing on Ring Main Unit (RMU)
Learn how to visualize and operate our Ring Main Unit (RMU) through this summary of its operational features and enhanced safety features for operating personnel's ease of access, secure and safe operation of the cable test facility
Condition monitoring of ring main units (RMU)
Find out how an effective asset management and capital improvement program aims to pinpoint the exact location of the distribution network needing maintenance and repair, without the guesswork.
Why choose smart Ring Main Unit (RMU)?
Faster power restoration thanks to decentralised schemes
Compliance with the latest cybersecurity standards
Expertise of the RMU market leader with +2.5 M installations worldwide
Smart Ring Main Unit (RMU) Connected Enabled
Our entry-level offer will help you improve everyday equipment maintenance and reduce OpEx costs. It features wireless thermal sensors and a smartphone app to replace infra-red thermal scanning. It also enables early detection of conditions that can result in electrical connection failures, fires, arc flashes, or worse.
Smart RMU (Ring Main Unit ) Connected Advanced
Discover our fully-optimised and integrated, advanced-level offer for controlling, metering, condition monitoring, and fault detection. Reduce operation and maintenance expenditures, and optimise your networks for increased demand. This advanced solution is available for RM6, FBX and Ringmaster.
What is the function of a Ring Main Unit (RMU)?
The main functions of a Ring Main Unit (RMU) are circuit control, isolation from faulty equipment, and controlling circuits to switch functions. The main ring unit is deployed in a secondary distribution system. It is mostly utilized to provide an uninterrupted power supply. It also protects your secondary side transformer from transient currents on occasion. You can use a switch fuse combination or a circuit breaker to safeguard the transformer, depending on your applications and loading circumstances. When paired with relays, the circuit breaker will improve the capacity to protect selectively compared to a medium voltage fuse. Ensure that the transformer's surge current is not operating incorrectly. Detection of phase-to-phase fault currents as well as low earth intensity. In various business domains, RMU (Ring Main Unit) electrical cabinets are utilized with a variety of secondary circuit distribution system applications, including input switching for transformer stations, integrated transformer stations, etc.
RMU is a set of factory-assembled switchgear employed at load connection points. It consists of a fusible switch, circuit breaker, switches that feed a distribution transformer, and two switches that can connect the load to one or both main conductors. RMUs generally have voltage and current ranges of up to 24kV and 360A, respectively. RMU cabinets are small in size, dependable, secure, simple to maintain, quickly replaced, and extendable. The RMU switchgear is manufactured in various voltages to meet the needs of both indoor and outdoor applications. In addition, RMU is used primarily for medium voltage power uses.
Why is Ring Main Unit (RMU) required?
RMU is required because it isolates faulty equipment from the rest of the equipment to prevent short-circuiting or causing further accidents. The Ring Main Unit, RMU, also features a self-powered protective system. This Numerical Relay with User Interface is based on microprocessors (different manufacturers have different designs). Over Current and Earth Fault prevention are among the features offered by this relay. Varying manufacturers may provide different levels of protection, or manufacturers may provide protection based on the user's preferences. RMU cabinets are a cutting-edge technology that makes managing the myriad power distribution issues a breeze. The RMU (Ring Main Unit) is a one-stop shop because it is safe switchgear that is simple to install and maintain, allowing utilities to increase network reliability and uptime while lowering operating costs.
RMU is required in an electrical system because it controls the circuit to switch functions, separates the defective equipment from the rest of the circuit and guards against overload, short-circuits current fault, and ground-fault current. In various applications, including input switching for transformer stations, integrated transformer stations, etc., RMU electrical cabinets are utilized in the secondary circuit distribution system. RMU is available in various voltage levels and may be installed indoors and outdoors based on the circumstances. At the load connection and junction sites of ring-type distribution systems, the Ring Main Units are utilized in underground cable distribution networks.