Enemalta has denied that a widespread power cut last week was caused by faulty settings at Malta’s end of the interconnector with Sicily.
The State energy provider yesterday insisted the power cut was a result of a lightning strike in Sicily, denying a story that appeared in the Times of Malta.
This newspaper yesterday quoted senior Enemalta sources contradicting statements made soon after the partial blackout by Energy Minister Konrad Mizzi, who said the outage was triggered by a fault in Sicily.
The sources claimed preventive settings at Magħtab were too low for the load which the interconnector was carrying at the time of the incident – 190MW.
This newspaper is today publishing a statement it received from the Italian company manning the Sicilian grid – Terna Rete Italia – in which it said the fault originated at the Magħtab terminal station.
The correspondence was received last Tuesday morning. For some reason, a few hours later, Terna “replaced” the statement with a joint press release with Enemalta, outlining the conclusions of the inquiry into the incident.
Still, the joint explanation seemed to corroborate the claim that the blackout was not due to a fault at Ragusa.
In their statement the two companies said protection systems at the Magħtab terminal station of the Malta-Italy interconnector had disconnected the electricity supply to prevent damage to the Maltese network, after lightning struck parts of the Sicilian network.
This triggered the automatic load shedding system, disrupting supply to several localities, the statement said.
However, Enemalta yesterday insisted this newspaper’s story was unfounded and baseless, reiterating that the disruption was caused by a lightning strike in Sicily.
Enemalta said this generated a surge in current which was registered at a six millisecond interval at the Ragusa and Magħtab terminal stations. This surge lasted for 1.4 seconds, which by international standards was an extremely long duration.
Consequently, the automatic system protection relays at Magħtab triggered the circuit breakers, to protect the interconnector which could have otherwise been damaged and remained unavailable for a longer time.
“The system protection operated perfectly to achieve its main objective – safeguarding the crucial interconnector equipment from the risk of permanent damage or undue pressure,” the State energy company said.
It noted that settings were perfectly in line with specifications of the original project design, which had been reviewed by all stakeholders and related international consultants.
Enemalta said that media allegations that “settings were too low for the high voltage carried” were untrue and technically incorrect, since voltage had nothing to do with issues related to earth current disturbances. Had the protection been “faulty” Enemalta would have risked damaging its infrastructure, it said.
“Since protection systems had worked perfectly, Enemalta was able to re-synchronise the Maltese and Italian networks in a very short time as soon as it received confirmation that the earth current disturbance in Sicily had been cleared.”
The company pointed out that the fact that no electricity supply disruptions were recorded in Sicily had no bearing on the consequences of the disturbance on the Maltese network, since the two grids had different specifications and levels of redundancy based on their respective capacities.
Enemalta said that, together with Terna, they were working to analyse all current systems involved to verify if additional measures could be taken to minimise the effects of such inevitable situations.
keith.micallef@timesofmalta.com
Translation of initial Terna statement
The initial statement issued by Terna on Tuesday, later “replaced” by a joint statement:
“We have been informed from Terna that there was no fault in the interconnector, which remained in service. The source of the fault was the untimely intervention of the protection systems at the Magħtab electricity station, manned by Enemalta, which has prevented the flow of energy from Italy to Malta, hence resulting in a blackout.”
ENEMALTA, TERNA's REPLY THIS MORNING
Following the publication of today's story, Enemalta and Terna issued another joint statement reiterating that the electricity supply disruption on August 6 was the result of a disturbance caused when a severe lightning storm hit the south-east Sicilian network infrastructure.
"The automatic protection relays at the Magħtab Terminal Station in Malta triggered the circuit breakers at the Magħtab Terminal Station to disconnect supply and protect the interconnector transformers and related infrastructure.
"In this regard, the protection relays operated adequately and on time to safeguard the interconnector’s equipment from the risk of permanent damage or undue pressure. These preliminary considerations are the results of the joint inquiries performed by the Maltese and Italian engineers.
"Further analysis is still ongoing to confirm if any additional measures can be taken to minimise the effects of such inevitable situations" they said.