Technology Into Life

Grid automation indoor control cabinets

Today's urban medium voltage cable network includes a lot of switchgear/ ring main units (RMUs) and transformers in secondary substations that manage the distribution of electricity via cable lines. RMUs in secondary substations can be placed in a building of their own, e.g., a compact secondary substation or integrated into an electrical room in a bigger building, such as a shopping center. 


To minimize the outage time and improve SAIDI (System Average Interruption Duration Index) and SAIFI (System Average Interruption Frequency Index) values, the indoor control cabinets bring online monitoring possibilities of the transformer and the RMU's switches and breakers. With online monitoring, you gain real-time information of the connection situation at each secondary substation. The control cabinets enable remote control functions with secure communication for executing commands when a fault in the grid occurs. 


ABB products and solutions


The likelihood of faults and the need for remote control varies in the network. Further, distribution grid reliability is prioritized differently in different network sections. The prioritization is based on the analysis of supply criticality. The level and roll-out order of the automatization varies accordingly. ABB’s control cabinet solutions have implemented a flexible approach to meet these requirements. The solutions available are grouped based on their capabilities into four levels: (1) monitoring, (2) control for providing fault isolation and power restoration, (3) measurements for enabling power flow management and (4) protection for improving safety and bringing protection selectivity further in the network.


The model works so that the functions available on a lower level are also available on higher levels. For example, remote monitoring and control (level 2) are also available on levels 3 and 4. Level 4comprises all the functions of levels 1-3 with the addition of protection functions.  In most networks, a combination of all four levels of distribution grid automation exists simultaneously.


The grid automation control cabinets for indoor applications are:

GAI2 for remote monitoring and control operations, including fault passage indication

GAI3 for measurements, utilizing modern sensor technology in the RMU to provide important information on the energy flow, load, and quality of each measuring point in the secondary substation. A transformer temperature can also be measured.

GAI4 for protection, providing selective protection together with the breaker and improving the quality and reliability of the grid, with the support of the integrated communication protocols.

Technical highlights

With the indoor control cabinet, it is possible to control one breaker and eight objects

Together with the sensor technology and the relay the cabinet provides precise measurements for protection or fault passage indication (FPI). Additional FPI functions can also be integrated into the cabinet. 

The control cabinets support IEC 60870-5-101 and IEC 60870-5-104, or Modbus and DNP3.0, as well as native IEC 61850 communication protocol

Supported communication interfaces are galvanic and fiber optic Ethernet or serial interfaces

Why ABB?

Proven state of the art technology

The control cabinets have been tested and found to excel also in harsh climates

Ease of use: easy to erect on site, start-up and take into use

and easy to monitor and maintain

Wide range of standardized communication protocols

Life cycle extension of earlier investments and improved reliability of the grid