KIUC Currents - Kauai Island Utility Cooperative

On average, KIUC experiences shorter outages
compared with other utilities as shown in figure
3. KIUC has a number of quick start generating
units that allow staff to react to outages by
bringing new units on in a timely manner in the
event of an interruption.
Figure 4 shows the frequency of outages.
The lower the number the better. In this index,
KIUC’s outage frequency is higher than other
Hawai‘i utilities.
This is primarily due to the “fuse­saving”
philosophy implemented in KIUC’s distribution
protection scheme, compared with the “tripsaving”
philosophy used by HECO. While the
number of interruptions are higher with fuse
saving, the outage duration usually is lower.
At KIUC, the distribution breaker is tripped
instantaneously to clear a temporary fault
without blowing a fuse. In most cases, the
distribution breaker recloses and the temporary
fault is cleared with no sustained outage.
However, the distribution breaker will “blink”
all customers on that given circuit.
At HECO, the distribution breaker is slow to
trip, allowing the fuse to blow to clear the fault.
Even if the fault was temporary, the fuse will
blow, causing a partial outage on the circuit.
The fuse must be manually replaced.
Figure 5 shows a breakdown by frequency
for the year 2009. Loss of power supply and
acts of nature are among the top two reasons
for outages.
Figure 5—2009 Sustained Interruptions by Frequency
Figure 3—CAIDI
Figure 4—SAIFI
Power Supply—25%
Acts of Nature—25%
Transmission—12%
Distribuon—18%
Scheduled—