Confirmed by one PGCB official. The blackout happened exactly this way said above.
The trip occurred on BD substation drawing power from India due to fault in line. It could happen anywhere in BD.
There were some problems with NLDC. Manually maintaining load.
Also PGCB, NLDC, PDB, DESA, DESCO, RPCL etc etc, power companies combined indecision made a huge role for long black out. It was job of PGCB. Which at last solved it.
Our rental power stations of small units made a huge role for this blackout. They cant maintain well in high voltage and under frequency.
132 kv lines gone for upto 145 kv. But our transmission lines aren't in that bad condition as the finance minister said. Our distribution lines are only in bad condition. Though for this huge voltage no equipments were damaged around the country.
Only some protection devices burned.
The system is improving and there is a plan to divide power grid in East and West section. The full report by a committee is underway.
@scorpionx @BDforever