Power producer put on notice over blackouts

Kampala. Electricity Regulatory Authority (ERA) has given Eskom Uganda up to September to fix the faults that led to power blackouts at Nalubaale and Kiira power stations in June.
The South African electricity company is responsible for maintenance and operation of Kiira and Nalubaale hydroelectric power stations.
The two power dams, located in Jinja, eastern Uganda, generate a combined capacity of 380MW of electricity.
A letter written to the managing director of Eskom Uganda Limited, dated July 17, 2017, that Daily Monitor has seen, demanded feedback on what it highlighted as a “total power system failure” that occurred on June 22 at the two power stations.
Following the notification of station blackout by Eskom Uganda, the power sector regulator noted that the South African electricity company is not fixing the things it is supposed to with urgency, leaving the stations exposed to uncertainty.
“The failed earth shield hook had been going through gradual failure which was worsened at the time of the incident (Power system failure),” the letter addressed to Eskom Uganda managing director, reads in part.
“There was evidence of burning as seen on some of the components which included exploded insulation discs, burnt blue phase conduct or failure on Njeru feeder, signs of burning on the main bus bar and some of the panels,” the correspondence further noted.
It also emerged that a similar incident occurred in September 2016. The failure was from the same substation tower though on a different section of the earth shield.
Good condition earth shield is crucial in protection against the effect of lightening among other things.
Before the September 2016 incident, the correspondence to Eskom chief executive officer said there was no work done on the earth shields for the time the South African company has operated the plant.
Worth noting is that Eskom engaged Uganda Electricity Transmission Company Limited (UETCL) to inspect the status of the substation earth shields and replace the defective ones within a week (ending July 7).
Eskom has also submitted the protection system operation sequence of events log to a private consultant and UETCL for investigation. Eskom further plans to inspect and test all the bus zone protection relays and examine the 132KV substation earth shields to ensure the incidence does not reoccur.
For that, ERA directed Eskom to submit its asset condition monitoring strategy by July 31.
It should also submit an update on refurbishment works, Inspect and replace all the worn out earth shield clamps for both 132kV and 33kV substations with better designed clamps not later than September 30.
The company was also directed to develop a maintenance work plan for inspection of the earth shields in the substation by July 31.
It should also demand and receive from Umeme and other contractors, work completion reports for the previous works undertaken in the shared facilities. This is in addition to submitting to ERA a copy of earth shield works completion report by Umeme by September 30.
“Review the generation facilities protection systems to ensure that such failures are localised to avoid system collapse. And a report should be submitted by September 30,” Ms Ziria Tibalwa Waako, ERA CEO further stressed in her letter.

Eskom statement
A press release by Eskom Uganda, following the power blackout at Nalubaale and Kiira plants stated that on June 22, 2017 at around 17:48hrs, a blackout occurred at Nalubaale and Kiira Power Stations managed by Eskom Uganda Limited.
Preliminary findings show that the incident was triggered by an overhead earth shield wire which broke and fell on the live equipment below.
“The incident happened during stormy weather conditions. The fallen earth wire short circuited both bus bars causing all connected generators and loads to trip,” the statement read in part.
“Eskom engineers swung into action to handle the emergency. The damaged equipment was isolated and the system made ready for system restoration as coordinated by the system Operator. The first unit was on load and started supplying power within one hour. Full generation at the Complex was restored within three hours after the incident.
“Eskom in partnership with Uganda Electricity Transmission Company Limited (UETCL) and UMEME shall jointly investigate the cause of the incident and put in place measures to avoid a repeat,” it added.