5.2. ERMUSR 02-11-2014 Elk River
Municipal Utilities UTILITIES COMMISSION MEETING
TO: FROM:
Elk River Municipal Utilities Commission Wade Lovelette—Technical Services
John Dietz—Chair Superintendent
Al Nadeau—Vice Chair
Daryl Thompson—Trustee
MEETING DATE: AGENDA ITEM NUMBER:
February 11, 2014 5.2
SUBJECT:
2013 Electric Reliability Report
BACKGROUND:
Minnesota Rules Chapter 7826 Public Utilities Commission Electric Utility Standards cover
safety, reliability, service, and reporting requirements. Per 7826.0100(A), municipal utilities are
exempt from these requirements. However, the Elk River Municipal Utilities Commission
adopted a number of parts of this chapter as a Distribution Reliability Standard policy requiring
annual reporting on system reliability.
DISCUSSION:
In 2013, our reliability index numbers remain excellent. These reliability index numbers reflect
the condition of our robust electrical system as well as the superb response time from our local
line crews. This also reflects the local accountability, long term visioning on system design, and
ongoing system maintenance. The table below reflects the number of customer outage minutes
from 2004 through 2013.
Year #of Customers # of Outage Minutes # of Outages
2004 7773 393,926 84
2005 8398 558,140 59
2006 8804 314,510 73
2007 9163 67,845 47
2008 9067 155,768 57
2009 9170 46,706 49
2010 9207 526,144 77
2011 9576 297,359 51
2012 9285 71,496 57
2013 9285 55,451 31
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A number of reliability indexes are used in the electric industry to make it easier to compare
performance of electric utilities. These reliability indexes are:
Average Service Availability Index (ASAI)
ASAI is a measure of the average availability of the sub-transmission and distribution
systems to serve customers. It is the ratio of the total customer minutes that service was
available to the total customer minutes available in a time period. This is normally expressed
as a percentage.
ERMU's 2013 ASAI is 99.999% Availability. Last year was 99.999% Availability.
Customer Average Interruption Duration Index (CAIDI)
CAIDI is defined as the average duration (in minutes) of an interruption experienced
by customers during a specific time frame. It is calculated by summing the customer
minutes off during each interruption in the time period and dividing this by the number of
customers experiencing one or more sustained interruptions during the time period. The
resulting unit is minutes. The index enables utilities to report the average duration of a
customer outage for those customers affected.
ERMU's 2013 CAIDI is 118.23 minutes. Last year's CAIDI was 66 minutes.
System Average Interruption Duration Index (SAIDI)
SAIDI is defined as the average interruption duration for customers served during a specified
time period. It is determined by summing the customer minutes off for each interruption
during a specified time period and dividing that sum by the average number of customers
served during that period. The unit is minutes. This index enables the utility to report how
many minutes' customers would have been out of service if all customers were out at one
time.
ERMU's 2013 SAIDI is 5.97 minutes. Last year's SAIDI was 7.7 minutes.
System Average Interruption Frequency Index (SAIFI)
SAIFI is defined as the average number of times that a customer is interrupted during a
specified time period. It is determined by dividing the total number of customers interrupted
in a time period by the average number of customers served. The resulting unit is
"interruptions per customer."
ERMU's 2013 SAIFI is 0.0505. Last year's SAIFI was 0.117.
Another statistic staff gets concerned about is the average length of any outage. Elk River
Municipal Utilities' 2013 average length of outage was 120.61 minutes. In 2012 the average
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length of outage was 119.32 minutes. Electric utilities with a high percentage of underground
facilities will exhibit higher length of outage time than electric utilities with more overhead
facilities.
Staff reviews these statistics in detail to find ways to continually improve our system. These
statistics are very good compared to other utilities. In 2013, birds and animals caused the greatest
number of outages. Birds and animals resulted in 29.03% of our outage incidents, and
contributed to 4.93%of total outage time. Outages resulting from branches and/or trees made up
0.00% of our outage incidents and contributed to 0.00% of our outage time. This low percentage
is a reflection of the good tree trimming our crews do during the winter. Overall, weather related
outages accounted for 16.12% of the incidents and 83.26% of our outage time. Many investor
owned and cooperative run utilities "storm normalize"their reliability numbers by removing
"major outages"due to storms from their reliability index number calculations. Our reliability
numbers have not been storm normalized. Our numbers reflect these major outages and
represent what our customer actually experienced in 2013. Overall, our electric distribution
system is robust and our reliability is very high.
APPA compares our utility with other public power utilities in region 3. In comparison:
Average SAIFI for all utilities that use the eReliability Tracker, belonging to our
region, and are grouped in our customer size class
Our utility's SAIFI: 0.0505
Average SAIFI for Utilities Within our Region 0.6304
Average SAIFI for Utilities Within Your Customer Size Class 1.0026
Our utility's SAIDI: 5.97
Average SAIDI for Utilities Within our Region 214.0614
Average SAIDI for Utilities Within our Customer Size Class 201.0751
Our utility's CAIDI: 118.23
Average CAIDI for Utilities Within our Region 168.5448
Average CAIDI for Utilities Within our Customer Size Class 161.156
Our utility's ASAI: 0.9999999
Average ASAI for Utilities Within our Region 0.9995927
Average ASAI for Utilities Within our Customer Size Class 0.9996174
I plugged this year's numbers in the above tables to compare with APPA's numbers. This year
our outages will be submitted to APPA throughout the year and they will include them in the
tables. We will be using the eReliabilty Tracker to record all of our outages going forward.
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