In an electrical power distribution system, a ring main unit (RMU) is a factory assembled, metal enclosed set of switchgear used at the load connection points of a ring-type distribution network. It includes in one unit two switches that can connect the load to either or both main conductors, and a fusible switch or circuit breaker and switch that feed a distribution transformer. The metal enclosed unit connects to the transformer either through a bus throat of standardized dimensions, or else through cables and is usually installed outdoors. Ring main cables enter and leave the cabinet. This type of switchgear is used for medium-voltage power distribution, from 7200 volts to about 36000 volts.
A Ring Main Unit (RMU) with SF6 gas breakers is an advanced electrical distribution device used primarily in medium-voltage networks. The SF6 gas-insulated RMU combines compact design with reliable performance and high safety standards. Here's a detailed overview:
Key Features:
- SF6 Gas Insulation: Provides superior insulation and minimizes space requirements due to the gas’s high dielectric strength. SF6 gas is also a highly effective medium for quenching electrical arcs.
- Compact Design: RMUs with SF6 breakers are compact and suitable for urban and confined environments.
- Sealed Construction: SF6 units are sealed to prevent the ingress of moisture and contaminants, enhancing reliability and reducing maintenance.
- Safety and Reliability: Offers high safety standards with features such as interlocking mechanisms and advanced protection relays.
Applications:
- Urban Distribution Networks: Ideal for use in urban areas where space is limited and reliability is crucial.
- Industrial Facilities: Used in industrial plants to manage medium-voltage electrical distribution.
- Commercial Buildings: Suitable for large commercial buildings that require reliable and compact distribution solutions.
- Utility Substations: Employed in substations to ensure efficient and reliable distribution of electrical power.