TCN Asks AEDC To Close Supply Gap As Apo Transformer Trip Causes Blackout

The Transmission Company of Nigeria (TCN) said one of the 100MVA 132/33kV transformers at Apo substation developed a fault and tripped at about 12:56 a.m. on 22 May 2026, which it blamed on heavy rain that fell that day, the company’s general manager, Public Affairs, Ndidi Mbah, stated on Saturday.

TCN said initial inspection showed oil spillage around the transformer and that further checks by its maintenance crew had revealed faults with the red and yellow phase 33kV bushings. It said the red-phase bushing had been resuscitated and work was ongoing on the yellow phase.

The transmission company said it had asked the Abuja Electricity Distribution Company (AEDC) to take supply for customers on the affected outgoing 33kV feeders from other TCN feeders within AEDC’s franchise area to close the supply gap while repairs continued.

TCN also said its engineers were working to restore the transformer and apologised for the inconvenience caused to AEDC and affected customers.

Explaining, TCN said “Initial inspection revealed oil spillage around the transformer. However, further investigation by TCN maintenance crew revealed faults with the red and yellow phase 33kV bushings of the 100MVA power transformer.

“Presently, the red phase bushing has been resuscitated, while work is ongoing on the yellow phase.

“In view of this incident, TCN has requested that Abuja Electricity Distribution Company (AEDC) take supply for customers on the outgoing 33kV feeders connected to the affected 100MVA transformer at Apo Substation from other TCN feeders within its franchise area, pending completion of repairs.

“Our engineers are working assiduously to restore the transformer and sincerely apologise for the inconvenience the incident has caused AEDC and electricity customers fed from the affected feeders.”

AEDC said in a follow-up notice on its social media handle that it had received TCN’s directive but that the alternate feeders could not reach all the areas hit by the outage.

The distribution company said the transformer tripped on differential protection in the early hours of Friday, 22 May, creating a capacity constraint at the Apo transmission substation and affecting several feeders serving parts of Abuja.

AEDC said the available alternate power routes could only serve customers in parts of Kogi and Niger states and therefore could not restore supply to some Abuja areas. It said it was working closely with TCN to support repair and restoration efforts and expected power to be returned to the impacted lines as soon as possible.

AEDC acknowledged the TCN’s directive, and notifying its customers, but regretted that the supply from those alternative feeders unfortunately couldn’t be distributed to the areas impacted by the tripping of the 1LOOMVA transformer on differential protection indication in the early hours of Friday, 22 May 2026, which resulted in capacity constraint at the Apo Transmission Substation, affecting supply to several feeders serving parts of Abuja.

It however assured that with the efforts being made by both parties, power supply was expected to be restored to the impacted lines a soon as possible.

“These alternative power routes can only meet our customers in Kogi and Niger. Notwithstanding, we wish to inform our esteemed customers that we are working assiduously with the TCN to support restoration efforts and reduce the impact on affected customers,” AEDC said.