Ring Main Unit

Ring main unit is a type of cabinet used for ring power supply.

The expandable SF6 ring main unit can be combined freely, with a small size, safety and reliability, and no maintenance required. The load switch uses SF6 gas as insulation and arc extinguishing medium, and the constant magnetic field rotary arc method makes it have strong arc extinguishing ability, good breaking performance, low overvoltage, long electrical life, and maintenance free arc extinguishing chamber. The load switch fuse combination device has a three position function, complete sealing, reliable operating mechanism and locking. The grounding switch has a short-circuit closing function. The cabinet is made of stamped and bent aluminum zinc coated plate, which is sturdy and reliable.

The ring main unit includes switch room, busbar room, cable room, mechanism room, and control and protection compartment.

The main primary components of the ring main unit are:

1) Load switch

Load switches have a certain load breaking capacity, which means they can be energized and tripped during light loads, but should not be operated frequently. Generally, load switches are equipped with fuses and have stronger arc extinguishing capabilities than isolation switches.

After the circuit breaker disconnects the circuit, due to the disconnection of the isolation switch, the electrified and non electrified parts can be clearly isolated, serving as an auxiliary switch.

Due to the lack of intuitive external indicators for the position of circuit breaker contacts and the inability to ensure that their indication is consistent with the position of the contacts in some cases, it is necessary to use isolation switches to clearly separate the energized and non energized parts.

In addition, isolation switches have a certain natural arc extinguishing ability and are commonly used for the input and disconnection of equipment with low current such as voltage transformers and lightning arresters, as well as for the connection between a circuit breaker and several devices, making the switching of the circuit breaker through the isolation switch more flexible and convenient.

3) Circuit breaker

A switch device that can turn on, carry, and disconnect current under normal circuit conditions, and can turn on, carry, and disconnect current under abnormal circuit conditions within a specified time.

4) Grounding switch

Mainly used for equipment maintenance, in order to prevent sudden power outages during the maintenance process, both ends of the maintenance equipment must be grounded.

The grounding switch of the high-voltage distribution cabinet is usually used for grounding the output load side. When we are inspecting the load side of the high-voltage distribution cabinet (such as tightening bolts, disassembling cables, etc.), we need to disconnect the switch and close the grounding switch of the distribution cabinet at the same time. This can prevent sudden electric shock accidents caused by incoming electricity, and also discharge the remaining charge, which is conducive to maintenance safety.

5) Contactor

The contactor cannot open or close the load current and is suitable for frequent operation scenarios.

Intelligent distribution

Real time monitoring of operating conditions

Remote monitoring and control of the electric ring main unit.

Remote monitoring of line load, real-time monitoring of the load situation of each branch line and segmented line, timely detection of overloaded lines, and improvement of the lean level of power grid planning.

Remote control function usage

Reduce the workload of on-site switching operations for the team and shorten the switching operation time. The operation time will be reduced from 2.5 hours to 0.5 hours.

The operation of the interconnection switch for the hot standby line has achieved rapid load transfer and flexible adjustment of the distribution network operation mode.

FA function

After a line fault causes a trip, the main station determines the fault area based on terminal telemetry signals and automatically isolates the fault.

The troubleshooting time has been reduced from approximately 2 hours to around 2 minutes.

The reliability of power supply has increased from 99.96% to 99.997%.

Intelligent ring main unit realizes technical processes such as fault location, fault isolation, load monitoring, line transfer, and live loop transfer.

The most basic requirement for achieving automatic restoration and self-healing of power lines after eliminating faults in the distribution network is to have efficient intelligent equipment.

Intelligent distribution grid self-healing refers to the ability of the distribution system to detect system faults in a timely manner, warn of unsafe states, and take corresponding actions to ensure that it does not affect the normal power supply to users or minimize its impact.

The ring main unit uses digital technology to monitor the opening and closing conditions of switches, and connects appropriate contact lines according to the operation mode of the line, indirectly enabling automated monitoring without increasing excessive equipment input. Through remote control operation of the "human-machine decision-making system", the power supply capacity of the area can be increased with slight adjustments to the operation mode.

distribution automation

Automated management of monitoring and control of 10KV system distribution network, optimization of urban distribution network structure, rational and efficient electricity management, timely prevention of accidents and timely handling of faults.

The ring main unit and its DTU terminal are the basic units of distribution automation and an important component of the entire distribution automation system. The complete set of intelligent ring main unit automation equipment can achieve technical processes such as fault location, fault isolation, load monitoring, line transfer, and live loop transfer.

The most basic requirement for achieving automatic restoration and self-healing of power lines after eliminating faults in the distribution network is to have efficient intelligent equipment.

Intelligent distribution grid self-healing refers to the ability of the distribution system to detect system faults in a timely manner, warn of unsafe states, and take corresponding actions to ensure that it does not affect the normal power supply to users or minimize its impact.

The intelligent ring main unit uses digital technology to monitor the opening and closing conditions of switches, connects appropriate contact lines according to the operation mode of the line, and indirectly enables automated monitoring without increasing too much equipment investment. Through remote control operation of the "human-machine decision-making system", the power supply capacity of the area can be increased with slight adjustments to the operation mode.

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