No light shed on Nov 29 and Dec 3 blackouts

Root causes of power outages still unidentified by eight-member committee, sabotage by CEB staff not ruled out

A committee that investigated the total blackout of December 3 last year has been unable to find evidence to substantiate the Ceylon Electricity Board’s (CEB) claim that its root cause was an earth fault.

It has also not found grounds to “eliminate the allegation” that the outage, along with a similar one on November 29 last year, was caused by deliberate actions of the CEB staff involved in the operation and maintenance of transmission assets ( transmission protection equipment in particular), the eight- member committee’s interim report, leaked to media, said.

“The verbal explanations presented at length to this committee by various branches of the CEB have so far failed to establish a cause of the failure backed by scientific data or any other proof,” it said.

Appointed by the Power Ministry, the committee was asked to probe the power system failure on December 3. But it also examined the total blackout that took place November 29 because of similarities between the two ( both initially involving the Kotmale- Biyagama 220 kV transmission line).

“The CEB has stated the root cause to be an earth fault on both occasions,” the report, leaked to the media, said.

“We have so far been unable to find any physical proof or confirmation, or technical reasoning that would substantiate this claim made by the CEB officials.”

Within hours of the outage on December 3, then CEB General Manager M. R. Ranatunga told media he suspected sabotage due to CEB engineers deliberately prolonging restoration activities. The Criminal Investigation Department was also deployed.

The committee referred to data, information, reports, manuals, etc, made available by the CEB on request. It made site visits and interviewed at least six senior CEB officials. It expects to provide a more detailed analysis, conclusions and recommendations in the final report.

During investigations, the committee was “surprised to learn” that certain records for December 3 related to lines one and two of the Biyagama grid substation were not available and "the explanation received on the missing records was that a possible overwriting may have taken place due to short internal memory storage capacity of the relay."

“However, CEB engineers have not shown us any statement in the manufacturer’s literature that confirmed this position,” the report said. This, and other observations, "raises an uncertainty whether records have been altered, we believe further investigation by experts of the OEM or an independent IT professional conversant with the equipment is warranted."

The CEB’s transmission network has a transmission system with state- of- the- art protection equipment from leading manufacturers around the world, its interim conclusions say. Many transmission substations have world class disturbance fault recorders so that in- charge CEB engineers are able to analyse and identify any disturbance of the system quickly and precisely.

“It is not possible, therefore, that the incidents on November 29 and December 3 are events that have evaded a highly sophisticated monitoring and protection system so no credible explanation can be found as to the cause of these two system failures,” it said.

“If that were the case, millions of dollars CEB has invested on installing, upgrading and maintaining transmission assets over the years have not paid off.”

“We express strong doubts that the protection relays have been accessed by those with level 1 access privileges and the records have been tampered with,” it asserts.

“It is paramount, therefore, to investigate this issue and implement the necessary safeguards and checks for personnel accessing relays, DFR [ digital fault recorder] and substation automation systems.”

The committee was headed by Prof. Lilantha Samaranayake f rom t he Unive r s i t y of Peradeniya's Department of Electrical and Electronic Engineering.

The CEB has lodged its response to the committee. It maintains that during the incident on December 3, a phase C-earth fault had occurred in the Biyagama- Kotmale line 2, resulting in single pole tripping of a circuit breaker.

“According to the schematics, Circuit Breaker open status shall be received only when all three phases are open. However, due to an error in field wiring Circuit Breaker status was received incorrectly to the control panel.” the committee said.

In layman terms, this means the wires were wrongly connected in the protection system.

“Inspection of field wiring in Kotmale line 1 and 2 has confirmed that the connections made in the central cubicle box of the circuit breaker are not as per drawing,” it said, elsewhere.