Ring Main Unit (RMU)
RMUs are used to control the flow of electricity and distribute it to different parts of a medium-voltage power network. They serve as compact and reliable distribution points for electrical energy. RMUs are designed to enhance the reliability of the distribution network by creating a ring or loop configuration. This means that if a fault or interruption occurs in one part of the network, power can still be supplied from an alternate path, reducing downtime and improving overall system reliability.
Types of RMU
3-Way RMU
A 3-way RMU typically has three separate feeders or connections. It can distribute power to three different directions or circuits. This configuration is often used in simpler distribution systems or where only three directions of power distribution are required.
4-Way RMU
A 4-way RMU, on the other hand, has four separate feeders or connections, allowing it to distribute power in four different directions or circuits. This configuration is used when more complex distribution networks are needed or when four directions of power distribution are required. The choice between a 3-way and a 4-way RMU depends on the specific requirements of the electrical distribution system, including the number of circuits to be served and the network's complexity.
Rockwill RMR Series
- The RMR series is completely insulated SF6 Ring Main Unit.
- This product is in conformity with the IEC standard and the design of a high safety combined switch cabinets.
- RMR series SF6 Ring Main Unit will take several functional units and connecting busbar assembly in sealed SF6 gas box, without any live parts exposed, with advantages completely insulated, live parts maintenance free, small volume, compact structure, convenient operation etc. The stainless-steel plate of cabinet with 3.0mm thick, which can effectively prevent moisture, corrosion caused by salt spray; Products passed the breaking and making test, dynamic thermal stability test, sealing test and mechanical test etc, the maximum guarantee the safety of people and equipment.
- The cabinet is suitable for indoor and outdoor installation, and it is not affected by the external environment, with high performance of anti-harsh environment. RMR series SF6 Ring Main Unit is widely used in industrial and civil ring network distribution system and power supply terminal, especially suitable for small secondary distribution substation, urban residential district, and other places.
RMU Technical Data
| 1 | Nominal Rated Voltage | 11kV |
| 2 | Rated Voltage | 17.5 kV |
| 3 | Rated Nominal Current (Main and tap switch) | 630 Amp |
| 4 | Rated Short time current (r.m.s) | 16kA, 1 sec |
| 5 | Rated short circuit making capacity (r.m.s) | 40kA (Peak) |
| 6 | Impulse withstand voltage | 95kV |
| 7 | Rated Power frequency withstand voltage | 38kV for 1 minute |
| 8 | Rated DC withstand voltage for cables | 42kV for 10 minutes |
| 9 | Mechanical Endurance for disconnector at 630A | 1000 operating cycles |
| 10 | Number of electrical operations at full current | 100 operating cycles |
| 11 | Rated short circuit making capacity and rated short time current for earthing devices shall be the same as for main contacts. | |
| 12 | Rated cable charging breaking capacity | 10 Amps |
LBS Ratings
| 1 | Rated Voltage | 12kV | ||||
| 2 | Nominal Voltage | 11 kV | ||||
| 3 | Rated Current | 400 Amp | ||||
| 4 | Rated short time and peak withstand current (1 sec) | 25kA & 63kA | ||||
| 5 | Rated short circuit making current, peak | 63kA | ||||
| 6 | Electrical Endurance | EI | ||||
| 7 | Mechanical Endurance | MI | ||||
| 8 | Lightning Impulse withstand voltage |
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| 9 | Power frequency withstand voltage |
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