PLN network vulnerable to disruption

PLN network vulnerable to disruption

The Jakarta Post, Jakarta

State electricity company PLN said the power outages that hit
most of Jakarta and its surrounding areas on Thursday evening and
Friday morning were caused by "disturbances" in its transmission
lines, and dismissed concerns the blackouts were precursors to a
power crisis.

PLN, however, has not yet been able to establish the exact
cause of the disturbances, saying the outages could be the result
of anything from a "simple kite string containing a bit of copper
to lightning".

PLN corporate secretary Muljo Adji AG said the company was
continuing to search for the cause of the two power outages,
which left 4.5 million customers without electricity for hours.

"So far we haven't been able to identify the cause of these
disturbances," Muljo said.

PLN attributed the blackout on Thursday evening to a
disturbance at its 100-kilometer-long high-voltage transmission
line connecting two relay stations in Cibinong, some 50
kilometers south of Jakarta, and Cilegon, some 60 kilometers west
of the capital.

Through this line, the two relay stations supply electricity
to Jakarta and West Java from power plants in the region and in
East Java.

Another disturbance was behind Friday's power outage, this
time at the transmission line connecting relay stations in
Cibinong and Sigalung, 50 kilometers southeast of Cibinong.

Here too PLN is still searching for the cause of the
disturbance, Muljo said.

"The problem with disturbances in transmission lines is that
they are hard to detect," he said.

Although the lines are supported by giant steel towers, they
can be easily disrupted if something becomes entwined in their
high-tension cables.

"It could be the string of a wayward kite that contains a bit
of copper or simply lightning," Muljo said.

If the kite string touched two of the tower's three high-
tension cables it could cause a short-circuit, and if there was a
fire the protection system would immediately cut off the power
supply, he explained.

"Meanwhile, there would be nothing left of the string for us
to locate."

But when asked how this could have happened at two separate
locations at nearly the same time, Muljo could not answer.

He admitted transmission lines were vulnerable and did not
dismiss the possibility of sabotage.

"We haven't found any indications of this (sabotage) ... but
it's possible."

National Police chief Gen. Da'i Bachtiar, however, ruled out
the possibility that sabotage was behind the blackouts.

On Friday afternoon, electricity gradually returned to homes
and offices in Jakarta and surrounding towns. But some areas on
the outskirts of the capital remained without power into the
evening.

Muljo said the disturbances in the transmission lines were
temporary, but had forced the 3,400-Megawatt Suralaya coal-fired
power plant in West Java to shut down.

Muljo said it took several hours to get the power plant back
onstream once it had been shut down. This, he said, was what kept
several areas in the dark for several hours.

PLN general manager of power distribution in Jakarta and
Tangerang, Margo Santoso, said the blackouts had nothing to do
with too much power demand overburdening the transmission lines.

"If that were the case, we would have asked large industrial
customers to unhook themselves from our system and use their own
power supplies to prevent the blackouts," he said.

Recent talk of a power crisis has concerned consumers, with
PLN frequently warning that it may not be able to meet the
nation's growing thirst for electricity.

Indonesia lacks new investment to cope with a surge in power
demand. PLN and experts have warned that without additional power
plants and transmission lines, the country may have to cope with
more blackouts as soon as two years from now.