By Adedayo Akinwale in Abuja
The Abuja Electricity Distribution Company (AEDC) has denied the claim by the Transmission Company of Nigeria (TCN) that one of its feeders caused Sunday’s fire outbreak at its Apo Transmission Station in Abuja.
The TCN had claimed that one of the feeders of AEDC that has a history of incessant tripping caused the recent fire outbreak at the Apo transmission station, resulting in the loss of 45MVA transformer and several other fittings.
But a statement Tuesday by AEDC General Manager, Corporate Communications, Mr. Oyebode Fadipe, said that the basic engineering explanation was that while the 33kV line belongs to AEDC, the protection system at the source belongs to TCN.
Against this background, AEDC therefore recommended a complete overhaul of the protection architecture of the TCN facility at Apo and elsewhere within AEDC’s franchise area.
Fadipe stated: “We are saddened by the fact that instead of doing a root cause analysis of the immediate and remote causes of the fire outbreak, which consumed such an expensive and critical asset with the intention of preventing a reoccurrence, the TCN has resorted to a blame game with a defence that is not in tune with standard engineering practice.
“For a transformer to go up in flames, both the line and transformer protection apparatus belonging to TCN failed completely. It is the reason for the total failure of their protection architecture that should be investigated. The transformer that caught fire belongs to TCN. The protection apparatus for it are in the custody of and under the maintenance and ownership of TCN.
“In any power system all over the world, tripping from outgoing circuits of feeders as a result of fault is an expected component of operations hence elaborate protection system is provided for such transformers against faults from outgoing feeders. These basic protection schemes are expected to fence the transformer from internal and external faults that usually occurs while in circuit.”
Fadipe explained that for such a facility, there are four levels of protection.
He said: “There is the protection at the feeder level (feeder H13 accused of causing the fire and property of AEDC). The 2nd level of protection is the protection that exists on the 33kV incomer (property of TCN) and this exists between the secondary side of the transformer and the busbar in the control room of TCN.
“The 3rd level of protection which is in-built in the transformer are of various types and they include winding temperature, oil temperature, pressure relief, buckholz, standby earth fault and restricted earth fault. This is also within the control of TCN.
“The 4th level of protection for such a facility is the protection on the 132kV side of the 45MVA, 132/33kV side of the transformer. This is also under the control of TCN. Of the four levels of protections, three of them which are the most critical are owned, controlled and maintained by TCN.”
Fadipe stressed that the essence of these multilayer protection scheme was to ensure that where one of the protection devices fails, the others would come to the rescue of the electrical apparatus.
He added that in the logic of TCN, the failure of one is the failure of others whereas the activation and performance of the other three, which is under its control was not dependent on the one (feeder H13) alleged to have triggered the fire incident.
AEDC however commended the Fire Service of the NNPC and Federal Capital Territory for saving AEDC customers from what could have been a calamity of immense proportion.
It also assured them that it would continue to invest in its network in order to provide customers with world class service.