Based on the press release, the source of the problem was at the Malakal Power Plant (MPP), specifically the switchgear in the Malakal substation
The main cause was insulation failure involving the current transformer and the insulation connecting the main line leading to the ALCO generator. A current transformer is designed to provide a current in its secondary coil proportional to the current flowing in its primary coil.
This equipment is necessary for transforming higher electrical current into lower values ideal for relaying and metering purposes.
These current transformers are tightly sealed and coated with special fibra-like insulating materials that sustain high voltage exposure.
These materials are used in parts of electrical equipment, also called insulators or insulation, intended to support or separate electrical conductors without passing current through themselves. The term is also used more specifically to refer to insulating supports that attach electric power transmission wires to utility poles or pylons. Because the insulations had saturated or deteriorated the electric current was not passing through but instead flowed outside onto the ground causing a ground fault. This ground fault caused the Malakal Substation to shut down affecting all running units in both the Malakal and Aimeliik power plants.
With the Malakal Generators shut down, the Aimeliik Power Plant (APP) was shut down as well. MPP and APP both provide Koror and Babeldaob with 10 Megawatts (MW) of power which is the current average demand. However, with the MPP down, APP shut down as well because of under frequency meaning Aimeliik was only producing 5MW to a 10MW demand. This under frequency caused the APP to shut down.
In cases where the MPP shuts down its engines, the ALCO generator in the MPP is used as a backup generator to start all the engines in the MPP: the Caterpillar, the Wartzilla and the Mitsubishi 12 and 13. This particular case however, involved the current transformer that connects this ALCO generator to the MPP. With this important connection burnt out, there was no source of power to the MPP.
PPUC crew then decided to have the APP provide power through its backup generator to the MPP to start the engines. This is normally done by having the Caterpillar (CAT) engine in the APP provide power to start the MPP Generators. Coincidentally when the APP crew had tried to start the CAT, the starter and the breaker encountered problems. This was the first time that this has ever happened and was totally unexpected from the mechanics. PPUC crew had to transport a starter from MPP to APP in order to get it running.
It took PPUC crew about 7 hours to trouble shoot the breaker problems in Aimeliik and repair the problems at the Malakal Substation.
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