On Thursday 07/03/19 at 16:52 hours, two of the three 765 kV lines from Guri (on the Malena - San Gerónimo B section) were on fire due to a forest fire in the line corridor due to lack of maintenance.
This caused the disconnection between the power loads and the main source of generation (Guri), or what is known as "load rejection", which caused the immediate shutdown of three units of the Guri dam (Units 15, 17, and 19).
This output is the result of the overspeed to which these machines were subjected when the associated protections ran, causing the 5CM protection to actuate, causing the immediate mechanical stop.
In spite of being a clearing of electrical lines in the San Geronimo Substation, for this case the protection that removes the service units are the mechanical overspeed protections.
Since the frequency of the system was very high, it was necessary to manually remove Guri Unit No. 12 and all the Macagua dam 2 Units that were in service at that time, plus Caruachi Units 1 and 4, and the operating unit of what is known as Plant Sidor (the only thermal generator), which caused the total collapse of the system (blackout).
The National Electric System (SEN) had a separation scheme for areas, which allowed separating the different areas.
that had their own generation from the rest of the country.Unfortunately they could not avoid the dragging of the Great Caracas due to the very weak generation that must be contributing the thermal generation plants located there, being the demand of the Great Caracas in the order of about 2000 MW and I don't think they are self-sufficient, which is why the Greater Caracas was also lost.The rest of the SEN inevitably collapses due to the shutdown of 765 kV lines, and the shutdown of 400 kV lines also coming from Guri, Macagua and Caruachi.
During the last few years adjustments of protections have been made to allow for the daily security violations of energy transport from Guri, it is possible that at this time they are making it difficult to re-establish electric service, experts say.
It was foreseeable that a second general blackout would occur while maneuvers were being made to restore it.
Unfortunately, experts in the field are out of the corporation and re-establishing service in a network such as Venezuela is complex.
Many transient type surges must be occurring when circuit breakers are closed. It is not known if those responsible are trained to face the maneuvers and the possible consequences.
Original thread in Spanish by Maibort Petit