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Smart Ring Main Unit | Schneider Electric Hong Kong

Improve energy availability

Reduce outage time by detecting faults early and automatically reconfiguring the network afterwards. Integrate intermittent and distributed generation smoothly to maintain energy quality and stability.


Optimise network performance

Get your grid ready for growing energy demand. With advanced analytics, you can optimise asset management, manage load shedding and peak shaving, and reduce technical and non-technical losses.


Why choose our smart RMU
  • Enjoy the advantages of grid connectivity without worrying about the security of your data. The smart RMU is compliant with IEC 62351, IEEE 1686 role-based access control (RBAC) and Achilles Practices.
  • Benefit from reduced maintenance costs with smart sensors for substation monitoring.
  • Improve energy availability with a cost- and time-effective solution (SAIDI).

The new world of energy

Discover how digitisation, decarbonisation and decentralisation are transforming the energy world.

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.
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Smart RMU Connected Enabled | Schneider Electric Hong Kong

Ringmaster

Find out more about our MV ring main units for outdoor applications.
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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.