According to the National Electrical Coordinator, “the intervention in the protection system was carried out without informing the CDC (National Energy Dispatch Center) of the Coordinator and without the corresponding work permit.”

The National Electric Coordinator (CEN) provided new details of the blackout that affected 14 of the 16 regions of Chile during the afternoon of January 25 of this year, forcing the Government to declare a curfew.

The autonomous, public-law body that, as its name suggests, is in charge of coordinating the operation of the national electrical system, submitted a report to the Superintendency of Electricity and Fuel (SEC) in response to a letter from the supervisor, explaining that the Colombian parent company, ISA InterChile, caused the blackout with an unreported maneuver and without the respective work permit.

Among the main points of the letter, the SEC requested the “causes and analysis of the failure, indicating its nature, evolution, and immediate and mediate causes, as well as the actions that the CEN has implemented or has planned to implement to avoid or reduce the probability of occurrence of events with similar characteristics that put the continuity of the electrical supply at risk.”

The response of the CEN

In his response, to which BioBioChile had access, the Electrical Coordinator began by indicating that, until moments before the forced disconnection by protections of both circuits of the 2×500 kV Nueva Maitencillo – Nueva Pan de Azúcar line, the National Electric System (SEN) “was operating in a stable manner.”

However, the CEN explained that since 1:35 p.m. there was a limitation report in force, submitted by InterChile, through which the power transmission company reported that "a failure was verified in the main communications module of function 87L for circuits 1 and 2 of the NMAI-NPAN line (Nueva Maitencillo – Nueva Pan de Azúar). The backup communications system is fully operational for the protection functions of both 500 kV circuits of the NMAI-NPAN line."

In this scenario, the Electrical Coordinator indicated to the SEC, "given the redundant protection scheme that both circuits of this transmission line have, and there being no warning from the Interchile CC regarding the possibility of any improper operation of protections or that in the event of a failure the protection scheme would not act adequately, the normal operation of the National Electric System should be maintained."

Without warning and without permission

However, according to the CEN, at 3:15 p.m. and while the personnel in charge of ISA InterChile "were on site trying to normalize the communications channel of the line differential function (87L) of the protection system No. 1 for both circuits of the 2×500 kV Nueva Maitencillo – Nueva Pan de Azúcar line, after its resynchronization attempt, the unexpected actuation of said function 87L on both circuits of the aforementioned transmission line occurred, which should not have occurred."

Five days after the incident, the Colombian-owned firm itself informed the CEN that “at 15:15 (hours), in the attempt to recover the channel and during the resynchronization of the differential line function of the aforementioned protections, an unexpected and unforeseen action of said protection function occurred.”

Regarding the latter, the CEN was categorical in its response to the SEC, stressing that “the intervention in the protection system was carried out without informing the CDC (National Energy Dispatch Center) of the Coordinator and without the corresponding work permit.”

As a consequence of said maneuver carried out by ISA InterChile, without permission and without notice, both circuits of the 2×500 kV Nueva Maitencillo – Nueva Pan de Azúcar line were closed, unleashing a domino effect that spread to the parallel 220 kV transmission system “due to the magnitude of the untimely increase in the level of load transfer, causing the opening by protections of the 220 kV circuits that operated in parallel with the 500kV system.”

In effect, the CEN adds, the National Electric System “was separated into two electrical subsystems.”