A team of Canadian consultants assigned to investigate the July 15, 2006 islandwide power cut has raised “serious questions” as to why system defects at the Jamaica Public Service (JPS) Company Limited were not recognised and dealt with promptly.

In a report tabled in the House of Representatives on Tuesday, the team said that among the immediate causes of the outage was the failure of the protections at Duncans substation to clear the short circuit on the Bogue-Duncans line in a timely manner.

“This failure was due to the dc breaker, supplying the relevant relays, being in the open position for no explainable reason and the alarm that would have warned staff in the control room being disconnected, also for no apparent reason,” the report said.

It said that, in addition, the A-phase voltage signal to the Spur Tree protections was not available “a serious issue for the integrity of the protection systems”.

“All of the above raise serious questions as to why system defects were not recognised and dealt with promptly,” the team said.

The team also said that they discovered that the Jamaica power system is “inherently vulnerable to transient instability,” a failure mode that can take just a few seconds to initiate system collapse.

“This has serious implications for the Jamaica Public Service Company Limited’s (JPS’s) reliance on the Under Frequency Load Shedding (UFLS) scheme, as a first line of defence against generation/load imbalance, when the system is at risk of becoming unstable,” the report added.

The team said the premature and incorrect tripping of generators at Bogue and Jamaica Energy partners (JEP) 1 and 2 led to a severe imbalance between generation supplies and the load demand, as well as the failure of the UFLS scheme to trip sufficient load to balance the system.

“This is an endemic problem because the UFLS cannot trip load fast enough when there is system instability. The risk of future all-island shutdowns will remain high until these and other problems are ameliorated. These problems should be dealt with as soon as possible,” the report said.

The team also commented that, while the JPS concluded that the faulted line cleared itself in less than a second, they could show evidence from the analysed data that the fault stayed on the Bogues-Duncans line for an extended period of time, and that the settings on the back-up relays at Kendal and Bellevue were such that they could never see the faulted line”.

“These differences have serious implications for the end goals of providing better reliability,” the report stated.

The team, composed of individuals from two Canadian firms – Gowlings Consulting Inc, and Rusnov Associates Limited- studied the technical, engineering and operational issues which led to the blackout, as well as the regulatory and legal frameworks involved, at the request of the Ministry of Industry, Technology, Energy and Commerce.

They made a number of recommendations including: correcting the immediate causes of the blackout; improve the effectiveness of protection systems; strengthen power system planning processes; improve operations and situational awareness; improve energy preparedness and system restoration; improve facilities maintenance; and improve personnel training.