Incorrect labelling caused Tuesday blackout

Lawrence Seretse | Tuesday January 21, 2014 17:27

 

One of the first things to be identified, according to insiders at Morupule B, was that wrong labelling caused the outage.

“The Chinese had labelled two different valves with the same name, Jacking Oil, instead of one being labelled Lubrication Oil.  Normally when the unit is running Jacking Oil Valve is open while Lubricating Oil Valve is closed.

 This is to supply oil to bearings and all parts that need constant lubrication when the unit is running,” explained a source.

He said when the operator found that ‘Jacking Oil Valve’, which should have been labelled Lubrication Oil Valve, was closed while the unit was running.  He picked it as an abnormal situation and proceeded to open it.

“In actual fact it was the lubrication oil that he cut hence protection devices picked the loss of lube oil as is called in industry jargon and tripped the unit.  The error of labelling was realised and corrected accordingly,” he clarified.

He further explained that the second trip [Unit 4 again] was apparently caused as a result of a unit circuit breaker opening.

“This meant auxiliary power could not be supplied to unit auxiliaries (equipment that directly keeps the unit running, that is, various air fans, pumps, motors and others). Normally when this happens there is an automatic switch-over so that the other running unit [in this case Unit 1] supplies the other unit auxiliaries,” he said.

Source said: “However, this switch-over did not happen hence the unit tripped. The causes of the unit breaker trip as well as the failure of change-over are still being investigated.”

The complexity of the defect and the requisite skills would determine the down time to fix these faults.  He explained that some defects like the poor labelling are called ‘nuisance trips’ and do not require any skill but rather vigilance.

“The issue now becomes, how many of such (mistakes) did the Chinese do?  It is a time-consuming task to go through every equipment of the plant to check for such,” he said.

The insider revealed that some defects that can be fixed in a very short period of time occur in areas where it is very hot.  Boiler operating temperature is 850-900°C hence much of the time would be consumed by cooling down of the plant. Typically, the cooling down of the plant would take a minimum of 48 hours depending on the location of the fault. The cost to identify and rectify the problems would certainly run into millions of Pula depending on the down time, skills needed and spares required.

“The people best placed to give cost estimates in terms of lost MW are the National Control Centre in Segoditshane,” said the source.

He said some outstanding defects are well documented and known by Botswana Power Corporation (BPC) while others are discovered during the running of the plant.

 “Certainly we expect the Chinese to disclose their shoddy work,” he said.

Currently, Unit 1 and 4 are running but only Unit 1 was running during the Tuesday load shedding.

He said: “The output from any one of these generators depends on many factors and varies from day to day. Even temperature rise has a bearing on how we operate these machines.”

About sourcing of power from other countries he asserted that it is still an ongoing process since South Africa can no longer afford to supply Botswana.

Mozambique is one of the countries the Ministry of Minerals, Energy and Water Resources has had negotiations with.

Meanwhile, CNEEC has distanced itself from the unfortunate faults that caused the Tuesday blackout. They allege that when they handed over Unit 4 to BPC at the beginning of January it was on grid and running smoothly.

CNEEC maintained that STEAG was incapacitated when it comes to operating Chinese equipment and it was the only possible reason why the blackout occurred.

“We do not know what happened, ask BPC,” a source at CNEEC said, “They took over the unit and all its operations.  The possibilities of the remaining plant producing a little more than 90MW cannot be ruled out,” he noted.

The CNEEC source claims that STEAG is unfamiliar with Chinese equipment, but BPC will not come clean about this. He said that they might not have been paying attention to the coal supply, which gets a bit tricky and challenging during rainy periods.

“BPC and people at seniority level know where the problem is and they can avoid these things if they continue to hire Chinese companies,” he claimed.

Efforts to reach BPC proved futile at the time of going to press.