CEMIG monitors condensive Bushings using a Treetech System

CEMIG’s – Companhia Energética de Minas Gerais (State of Minas Gerais Power Utility Company) strategic location and large market serviced place it among Brazil’s largest and most important power utility services.

CEMIG’s concession area covers approximately 96% of the territory of the state of Minas Gerais, Southeast region of Brazil, an area of 567,478 mil km2, the equivalent to a country of the size of France. CEMIG has 54 generation plants in operation, 5 of which in partnership with corporate groups, with a predominantly hydro-electric generation base, producing energy to meet the needs of over 17 million people in 774 municipalities in Minas Gerais. In 2004, CEMIG delivered 37,897 GWh of power.

CEMIG is also present, in power generation and sales ventures in the states of Santa Catarina (generation), Rio de Janeiro (sales and generation), São Paulo (sales), Espírito Santo (generation) and Rio Grande do Sul (sales).

In order to have the electric energy reach the close to 6 million consumers, CEMIG manages the Latin America’s largest power distribution network and one of the world’s four largest, covering 367,437 thousand km.

In partnership with Treetech, CEMIG started monitoring the Condensive Bushings deployed in high-voltage equipment, in order to collect important variables for early detection of deterioration of bushing insulation. The Treetech solution is the BM Bushing Monitor, which allows on-line monitoring of the insulation’s capacitance and dissipation factor (tangent delta, with bushings energized.

The system monitor 3 HSP 500kV and three 230kV bushings on the same three-phase, 500-230kV 400MVA transformer through the BM-MMI interface module and 2 BM-MM monitoring modules, in addition to the respective adapters installed on each bushings test tap.

The set up also includes a digitizing system in the substation control room, where all the information is kept available on a database server. In addition to this facility, it is also possible to access the memory of the BM using a cellular phone modem and download the entire database set stored in the memory of the equipment. This Access can be done from anywhere with a phone line or Internet access.