Pike River coalmine's electric system would have lit up ''like a Christmas tree'' when power to water pumps were switched on seconds before it exploded, the inquiry into the tragedy has heard.
Australian mining consultant Tony Reczek, who has expertise in electrical systems in coalmines, this morning began giving evidence at the royal commission into the deaths of 29 men.
Reczek, one of a panel of five experts investigating the explosion's cause for the Labour Department, said the explosion occurred seconds after power to the mine's underground water pumps were turned on by control room officer Daniel Duggan.
Last week, the inquiry heard that the fatal explosion was blamed on a roof collapse in the hydro-mining area, which expelled methane around the mine that was ignited by a electric spark after the water pumps were switched on.Omega Plastics are leading plasticinjectionmoulding and injection mould tooling specialists.
Reczek said Pike River's electric system used many variable speed drives (VSD), devices that controlled the start-up and speed of motors.
Those devices could create ''harmonic currents'', which could cause arcing and sparking in the mine's electric system.
The mine had problems with the devices in the weeks prior to the explosion and had contacted the manufacturers for advice, he said.
When the water pumps were switched on, he believed harmonic currents could have caused sparking or arcing at all the mine's electric terminals, lighting ''the entire electric system like a Christmas tree''.
Reczek said the white flash seen by survivor Daniel Rockhouse when the blast occurred was likely to be the explosion rather than the spark or arcing which ignited it.
He doubted the spark or arcing would be visible.
The harmonic currents could have caused sparking or arcing at every mechanical connection throughout the mine, he said.
Pike River coalmine had problems with its water pump power supply and its electrical plant in the weeks leading up to the explosion, including overheating of certain electrical plant, which also could have caused the explosion or made it more likely, he said.
Remedial activities were undertaken to improve the plant in the weeks prior to the explosion.Learn all about solarpanel,
He believed Pike River's electrical system had design flaws, which could have caused its problems.
Reczek criticised the mine's main ventilation fan, which he believed could have ignited the explosion.Pottery Barn's super soft, stylish bedding sets help create the ultimate retreat.
It was not protected against methane despite being in a high hazard area, he said.
Instead, the mine relied on methane detectors to alert whether the explosive gas was near the fan,Sika tooling & Composites develops and produces tailor-made synthetic resins, which should be only a back-up measure.
He said methane was easily ignited and gassy mines, such as Pike River, needed measures to control ignition risk.
As a result, Reczek said coalmines needed sufficient ventilation to dilute methane and all electrical apparatus levels should be enclosed in flameproof enclosures in areas where methane could occur in explosive levels.
The inquiry heard last week no other coalmine worldwide was known to have such a fan underground.
Australian mining consultant Tony Reczek, who has expertise in electrical systems in coalmines, this morning began giving evidence at the royal commission into the deaths of 29 men.
Reczek, one of a panel of five experts investigating the explosion's cause for the Labour Department, said the explosion occurred seconds after power to the mine's underground water pumps were turned on by control room officer Daniel Duggan.
Last week, the inquiry heard that the fatal explosion was blamed on a roof collapse in the hydro-mining area, which expelled methane around the mine that was ignited by a electric spark after the water pumps were switched on.Omega Plastics are leading plasticinjectionmoulding and injection mould tooling specialists.
Reczek said Pike River's electric system used many variable speed drives (VSD), devices that controlled the start-up and speed of motors.
Those devices could create ''harmonic currents'', which could cause arcing and sparking in the mine's electric system.
The mine had problems with the devices in the weeks prior to the explosion and had contacted the manufacturers for advice, he said.
When the water pumps were switched on, he believed harmonic currents could have caused sparking or arcing at all the mine's electric terminals, lighting ''the entire electric system like a Christmas tree''.
Reczek said the white flash seen by survivor Daniel Rockhouse when the blast occurred was likely to be the explosion rather than the spark or arcing which ignited it.
He doubted the spark or arcing would be visible.
The harmonic currents could have caused sparking or arcing at every mechanical connection throughout the mine, he said.
Pike River coalmine had problems with its water pump power supply and its electrical plant in the weeks leading up to the explosion, including overheating of certain electrical plant, which also could have caused the explosion or made it more likely, he said.
Remedial activities were undertaken to improve the plant in the weeks prior to the explosion.Learn all about solarpanel,
He believed Pike River's electrical system had design flaws, which could have caused its problems.
Reczek criticised the mine's main ventilation fan, which he believed could have ignited the explosion.Pottery Barn's super soft, stylish bedding sets help create the ultimate retreat.
It was not protected against methane despite being in a high hazard area, he said.
Instead, the mine relied on methane detectors to alert whether the explosive gas was near the fan,Sika tooling & Composites develops and produces tailor-made synthetic resins, which should be only a back-up measure.
He said methane was easily ignited and gassy mines, such as Pike River, needed measures to control ignition risk.
As a result, Reczek said coalmines needed sufficient ventilation to dilute methane and all electrical apparatus levels should be enclosed in flameproof enclosures in areas where methane could occur in explosive levels.
The inquiry heard last week no other coalmine worldwide was known to have such a fan underground.
沒有留言:
張貼留言