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24KV Electrical Ring Main Unit (RMU)

24KV ring main unit(rmu) switchgear refers to the ring electrical distribution network, the main function of the electrical ring main unit is to achieve double loop or multi-loop power supply, so as to improve the reliability of electrical power supply.

It is widely used in the building, seaport, shopping malls and railways because of its advantages in small size, safe operation, and simple structure.

Ring main unit(rmu) switchgear has two different types of feeders as the incoming unit and outgoing unit, the incoming unit connecting with high voltage side and the outgoing unit(normally is F module) connect with distribution transformers. It could protect the secondary transformer from transients either from load or source side.

Features of 24KV Electrical RMU

 

There are 3 types of electrical Rmu switchgear according to the isolation medium:

Gas insulation with SF6, air insulation, and solid insulation.

All of these ring main units are used to divide the load current, switch short circuit current and transformer no-load current, a certain distance from the overhead line, the charging current of the current line, and play the role of control and protection.

Electric Ring main unit(rmu) is an important switch equipment for the secondary distribution system. It could be standard configurations and produced in big quantity and also could be extendable according to customer’s requirements.

Because of the advantages of the sealed tanker with SF6 gas, the electrical ring main unit could operate in normal condition for around 30 years without any maintenance.

The ring main unit is a switchgear (outlet switchgear) for each distribution branch. The busbar of this unit is also part of the ring trunk.

The ring network refers to a ring distribution network, in which the power supply trunk forms a closed ring, and the power supply supplies power to the ring trunk line and then distributes power from the trunk line all the way through the high voltage switch.

The advantage of this is that each distribution branch can take its power from its left trunk and its right trunk. When the left mainline fails, it continues to receive power from the right mainline.

When the right main line fails, it continues to receive power from the left mainline. This way, although the main power supply is single-circuit powered, However, similar to the two-way power supply, benefits are gained from each distribution branch, which improves the reliability of the power supply.

Ring6 24KV C-module F-module v-module
Switch disconnector Earthing switch Switch-fuse disconnector Downstream earthing switch Vacuum circuit-breaker Earthing switch/ disconnector
Rated voltage kV 12/17, 5/24 12/17,5/24 12/17,5/24 12/17,5/24 12/17,5/24 12/17,5/24
Rated frequency 5) Hz 50/50/50 50/50/50 50/50/50 50/5 0/50 50/50/50 50/50/50
Power frequency withstand voltage kV 284)/38/50 284)/38 /50 284,/38 /50 284,/38 /50 284)/38/50 284)/38/50
Lightning impulse withstand voitage kV 95/95/125 95/95/125 95/95/125 95/95/125 95/95/125 95/95/125
Rated normai current A 6 30/630/630 2001) 200/200/200
Breaking capacities:
-active load A 630/630/630
-closed loop A 650/650/650
-offload cable charging A 140/140/140
-offload transformer A 20/20/20
-earth-fault A 205/160/160
-earth-fault cable charging A 117/91/91
-short-circuit breaking current kA see2) 16/16/16
Marking capacity kA 52,5/40/40 52,5/40/40 see2) 5 12,5/12,5/12, 40/40/40 40/40/40
Short tirne current 3 sec,3) kA 21/16/16 21/16/16 16/16/16 16/16/16

1) Depending on the current rating of the fuse-link
2) Limited by high voltage fuse-links
3) Maximum rating for bushings Interface C (400 series bolted)
4) GOST version is available with 42kV power frequency to withstand voltage
5) For rated frequency 60Hz de-rating for current parameter needs to be applied

CEO Note

Hey! This is Tony, the CEO of Orecco Electric. Thanks for visiting our website and I hope to be a friend with you. I have 20 years experience in electric power transmission for primary distribution and secondary distribution, I would like to share my experience with you in this field, please contact me to discuss when you have any question about our products, I’m happy to help you. I provide free consultant for many clients, and if you need any help on power transmission, reach me any with with blow button.

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