Repairing RMU cabinets in Sapa town

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On August 28, 2022, ABB ASIA’s expert delegation had a business trip to Sapa town – Lao Cai. Here, the company’s experts directly checked and repaired the RMU cabinets here.

What is an RMU cabinet?

RMU (Ring Main Unit) or medium voltage cabinet is an electrical equipment with the function of connecting, measuring and integrating fixed type breaker with transformer protection function.

RMU cabinets are small in size, highly reliable, safe, easy to maintain, easy to replace and expand. Depending on requirements, RMUs are available in different voltages suitable for both indoor and outdoor installation.

Construction of cabinet RMU

The RMU cabinet is connected by output and input cable compartments by isolating switches and the transformer output compartment uses load breakers and fuse protection.

Switching elements include load breakers, circuit breakers and earthing switches, busbars and terminals. The elements are placed in the SF6 gas tank (made of special substances that are resistant to the environment such as dirt, grease, not rust).

RMU cabinets are divided and connected with each other by separate compartments, with 2 compartments, 4 compartments, 6 compartments RMU standards depending on customer requirements with functions.

In the past, most protection schemes for medium/low voltage transformers in the distribution network used common circuit breakers and fuses. It’s a simple and cost-effective solution. On the other hand, circuit breakers in the past were often expensive and used in high/medium voltage (HV/MV) stations instead of medium/low voltage (MV/LV) stations.

Recently, medium voltage cabinet manufacturers such as Schneider Electric have designed compact RMU cabinet circuit breakers incorporating SF6 gas insulators, self-powered relays and transformers with optimal design for a total cost of ownership. equivalent to the solution of circuit breakers and medium voltage fuses.

One of the reasons that electricity and private customers choose the circuit breaker solution is the requirement to improve service quality while optimizing investment costs. Circuit breakers with self-powered relays are easier to install than medium voltage fuses and are suitable for combined protection upstream and downstream.

Here are some pictures from the project

The image of the RMU cabinet has a gas leak


Remove and clean the Schneider RMU cabinet before finding the gas detection point


Recharge SF6 for RMU Schneider


Use the SF6 gas detector to find, detect and mark gas leaks on RMU Schneider cabinets


Replenish SF6 gas for RMU Schneider cabinets after re-welding the gas leak point


Discuss with customers about the treatment direction after detecting the gas leak point


ABB Asia Co. Ltd.  +84 902 336 426 provides the following services:

1/ New construction, installation, maintenance of substations from 22kV-110kV, underground cable 22-110kV.

2/ Repair medium voltage cabinets (RMU) 22kV- circuit breakers up to 500kV.

3/ Construction and installation of gas supply works, tanks, liquid gas tanks, supply stations, gas filling, liquefied gas

4/ Service of suction, recoverry,  filtration and filling of SF6 gas

5/ Provides ultra-pure gas, calibration gas, multi-component mixing gas up to ppm.

6/ Construction, installation and maintenance of refrigeration systems, cold rooms, clean rooms, central air conditioning systems

Checking leak on RMU ABB brand in Viet nam, then fix it for client.

ABB Asia Co. Ltd.

North Vietnam

  • Vinhomes Ocean Park Gia Lam., Ha noi

Central Viet nam

  • Hai Linh ward – Nghi Son city–Thanh Hoa Pro.

South Viet nam

  • 11A Hong Ha -Tan Binh Dis. – Ho Chi Minh
  • My Xuan ward – Phu My city – Vung Tau

Tel/zalo/whatsapp: +84 902 336 426 (zalo/whatsapp)

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Email 2:

Website 1: (Global)

Website 2: (Viet nam)

Website 3: (Viet nam)

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