UPDATE 1-South Africa's Eskom to increase power cuts as more coal units down

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JOHANNESBURG, Oct 27 (Reuters) - South Africa's state power utility Eskom said it would increase scheduled power cuts from midday on Wednesday because of further breakdowns at its coal-fired power stations.

Eskom regularly implements outages in Africa's most industrialised economy because of faults at its ailing coal fleet which has held back economic growth.

The outages will increase from "Stage 2" to "Stage 4," requiring up to 4,000 megawatts (MW) to be shed from the national grid, until Friday 5 a.m. (0300 GMT). After that they will be scaled back to Stage 2 until Saturday at 5 a.m.

"Over the past 24 hours a unit each at Medupi, Kusile and Matla power stations tripped while a unit each at Lethabo and Arnot power stations were forced to shut down," Eskom said in a statement.

"This constrained the power system further requiring extensive use of emergency reserves."

Eskom said total breakdowns amounted to almost 15,000 MW, while over 5,000 MW was out on planned maintenance. The utility has a nominal capacity of around 46,000 MW and supplies over 90% of the country's electricity. (Reporting by Alexander Winning; editing by David Evans)