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configuration comprising two parts: a 300-amp
Accusine PCS harmonic filtering and reactive
power compensation system, supported by a
static bank of capacitors (600kVar).
“We could have opted for a bigger Accusine
PCS unit and eliminated the static bank entirely,”
says Davies, “but for us a smaller unit with the
complementary static bank was a more costeffective
option. It works perfectly, with the static
bank correcting for the base load and lifting the
power factor correction to a certain level.
“The Accusine takes over from there, catering
for the more variable fluctuations. The advantage
of the Accusine is its speed – it performs the
correction in milliseconds. The static bank unit
is too slow, but it doesn’t have to deal with the
fluctuations.”
The site now operates with a power factor
correction ratio of 0.97 – and the penalty charges
have disappeared.
The most interesting part of the power factor
solution, says Davies, is that the load on the
transformer has been reduced. “That not only
translates into better overall reliability because
there’s less heat in the cables, but it’s also given
us scope to expand and adapt the site to market
developments.”
In fact, the sawmill has subsequently installed
a new kerf saw – it now represents the biggest
single load at the site – which allows crews to
process and optimise second-grade timber more
easily. “Overall, the new power factor correction
system has already generated thousands of
dollars in savings.”
Harmonics
So far, rogue harmonics haven’t been a problem
at the sawmill, but Davies is well aware that they
might become an issue as new technology is
introduced. “A significant advantage of having
the Accusine unit installed is that it also operates
as a harmonic filter. If harmonics did become a
problem, we would simply activate the Accusine’s
existing filter component.”
He says monitoring the site’s electrical load is
now simple thanks to the feedback provided by
the Accusine system. “The unit’s multi-functional
display provides good data, and I’m hoping to
install a SCADA system at some point to generate
monitoring, trending information and alarms more
easily.”
Project at a glance
Project type:
Low Voltage Power Compensation
and Filtering
Location:
Pukepine Sawmills Ltd., Tauranga,
New Zealand
Applications:
Hybrid VAR Compensation System
Main Products
> Accusine PCS
> Varset power factor correction units
Schneider Electric News December 2012 11