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Repair process for medium voltage circuit breakers containing SF6 . gas

Repair process for medium voltage circuit breakers containing SF6 . gas

Repair process for medium voltage circuit breakers containing SF6 . gas

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In power generation, transmission and distribution, at any stage, from production, transmission and distribution, medium voltage circuit breakers from 6 kV to 42 kV are indispensable. For example, with a hydroelectric turbine, the generator will generate a current with a voltage of 6-36 kV, with a very large current, from here using a terminal breaker to introduce a transformer, raising the current to 110 kV ( 123Kv) or 220 kv (245 kV). Terminal circuit breaker is also a special medium voltage circuit breaker, called GCB (generator circuit breaker).
After the current is raised to the grid from 110K -220 kV- 500 kV (123 kv-245Kv -550 kV), then it is transmitted (transmission) and then it is lowered to the grid or consumers from the grid. 110Kv – 22 KV (popular in Vietnam) today.

When going to large factories, or a residential area, people often build 110 kV substations to distribute to 22 kV highways, at these stations, there is a modern electrical switchboard system including, protection, distribution, fault reporting, here also contains medium voltage circuit breakers to bring out the roads and bring electricity to consumption.

These medium voltage lines (mainly 22 kV (24 kv) in Vietnam at present) are used to install loops for modern power stations with 3 basic components: breaker (containing SF6 gas), transformer, low voltage distribution cabinets, of course there are some other elements in medium voltage cabinets (MV – Medium voltage) such as TU, TI monitoring and measuring.

Thus, the above has presented the importance of medium voltage circuit breakers using SF6 gas, depending on the needs of use with high or low current, the structure of the circuit breaker (electrical cabinet) will be different. , in other articles, ABB Asia Co., Ltd. will analyze more so that users can understand better.

Here we will present the basic steps of the SF6 . gas-containing medium voltage circuit breaker repair procedure.

I.Main workload

II.Preparation and construction measures

II.1 Preparation

a/ Prepare the ground before construction

b/ Prepare equipment, tools and supplies:

c/ Allocation of construction personnel:

d/ Tools and construction equipment:

No Category Unit Quantity
1 Máy nén khí Máy 1
2 Máy hàn tig, kèm bình Argon Máy 1
3 Máy hút chân không Máy 2
4 Máy nạp khí SF6 Máy 3
5 Máy rò (ngửi) khí Sf6 Máy 3
6 Dụng cụ (tool set) (đủ bộ) Bộ 1
7 Roăng, mỡ Hộp 3
8 Hệ thống máy, thiết bị thí nghiệm Bộ 1
9 Khí SF6 Bình 1
10 Máy hút bụi Cái 1

II.2 Construction methods

1/ Checking procedure before SF6 . gas leak

2/ Procedure for checking leak point

3/ Process of detecting detection points

5/ Done


  1. When the construction needs to cut off the power, the construction unit will directly contact the investor and the power management board to take safety measures and deliver the grid for construction.
  2. All construction sites have signs
  3. The construction unit has a registration form for direct commanders, safety supervisors, and working workers.
  4. Check that the ground is closed.
  5. Finishing work on the day the construction team leader conducts the final inspection to ensure the safety of energizing.
  6. It is strictly forbidden for workers to drink alcohol or use other stimulants during working hours.
  7. All workers participating in the construction must be trained in electrical and occupational safety.
  8. All employees participating in the construction of the project are fully equipped with tools and labor protection equipment such as:
    • Protective clothing
    • Protective plastic caps
    • Safety shoes


1. Installation work

After construction, the site must be redone around the construction site as it was in its original state. During construction, it is necessary to pay close attention to protect the equipment around the entire construction work, clean it, and at the end of the day check the construction tools carefully to clean up to avoid loss. and cause accidents to people.
The power sources used in construction must be safe for everyone, strictly comply with the regulations on order, safety and industrial hygiene of the area.

2. Maintain hygiene

The transportation of tools for work must comply with the regulations of the factory management board.

3. Protection of technical infrastructure works

During the construction process, the contractor absolutely does not adversely affect the existing technical infrastructure system.

Some outstanding technical services of ABB Asia in 2023

  1. SF6 suction service with 1-3h time for all GIS, GCB . stations
  2. Vacuum service down to 1mbar  to 2h, for tanks, chambers 6-10 mr
  3. Service of recovering and thoroughly treating toxic gases for factories
  4. Repair service of liquefied gas tanks with pressure, clogged pipes
  5. Boiler Repair Service
  6. Technical services for cold rooms, refrigerated containers
  7. Mixed gas supply service for vegetables and fruits, exporting to Europe and America
  8. Recovery service, high pressure compression, extremely large flow

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