5.2 ERMUSR 04-11-2023Elk River
Municipal Utilities UTILITIES COMMISSION MEETING
TO:
FROM:
ERMU Commission
Mike Tietz —Technical Services Superintendent
MEETING DATE:
AGENDA ITEM NUMBER:
April 11, 2023
5.2
SUBJECT:
2022 Annual Reliability Report
ACTION REQUESTED:
Receive the 2022 Annual 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 several parts of this chapter as a Distribution Reliability Standard policy requiring
annual reporting on system reliability.
DISCUSSION:
In 2022, our reliability index numbers remain very good. 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
for the last 10 years.
Year
# of Customers
# of Outage Minutes
# of Outages
2013
9285
55,451
31
2014
9426
243,965
44
2015
9449
225,337
41
2016
10862
432,310
59
2017
11489
354,625
40
2018
12158
117,055
51
2019
12463
312,885*
59
2020
12604
197,884
51
2021
13038
628,670
61
2022
13228
174,500
50
*118,978 of these minutes are due to two separate transmission outages.
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Listed below are a number of reliability indices that are used by the electric industry to make it
easier to compare performance among utilities along with ERMU's 2021 and 2022 statistics.
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 2022 ASAI is 99.9974% Availability ERMU's 2021 ASAI is 99.9914% 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 sustained' 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 2022 CAIDI is 90.146 minutes ERMU's 2021 CAIDI is 126.25 minutes
System Average Interruption Duration Index (SAIDI)
SAIDI is defined as the average interruption duration (in minutes) for customers served
during a specified time period. It is determined by summing the customer minutes off for each
sustained' interruption during a specified time period and dividing that sum by the average
number of customers served during that period. The resulting 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 2022 SAIDI is 13.289 minutes ERMU's 2021 SAIDI was 49.261 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 sustained' interrupted
customers in a time period by the average number of customers served. The resulting unit is
"interruptions per customer."
ERMU's 2022 SAIFI is 0.147 ERMU's 2021 SAIFI was 0.39
' Only outages lasting longer than five minutes are included in the calculations, as defined by IEEE 1366.
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Staff reviews these statistics in detail to find ways to continually improve our system. These
statistics are very good when compared with other utilities. As indicated by the following pie
chart and statistics list, you can see the causes for the outages experienced in 2022.
Equipment Worn
4%
Electrical Failure
6'/
Manufacturing Defect
6%
Vehicle Accident
6%
Gtner
14%
Equipment
120
Squirrel
12%
LI
c�
6
0
Equipment
6
Vehicle Accident
3
4
Tree Manufacturing Defect
3
0
4Y-
Electrical Failure
3
<T>
Equipment Worn Out
2
0
2
VE
Equipment Replacement
1
0 .
Other - Wildlife
1
0 .
Human Accident
1
0 .
Contractor -Dig -In
1
4
isIdlife
1
AM
Total
50
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 customers experienced in 2022. Overall, our electric
distribution system is very resilient, and our system reliability remains excellent.
Please receive the attached American Public Power Association's (APPA) eReliability Annual
Report which contains published averages that can be used to better understand the
performance of our electric system relative to other utilities nationally and to those within their
region or size class.
ACTION REQUESTED:
Staff requests the Commission receive and file the APPA eReliability Tracker 2022 Annual
Report for Elk River Municipal Utilities.
ATTACHMENT:
• APPA eReliability Tracker 2022 Annual Report for Elk River Municipal Utilities
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