Section PSC 113.0602 - DefinitionsIn ss. PSC 113.0602 to 113.0605, the following definitions shall apply:
(1) "Average number of customers served" means the number of active metered customer accounts as available in a utility's interruption reporting database on the day that an interruption occurs.(2) "Circuit" means a set of conductors serving customer loads that are capable of being separated from the serving substation automatically by a recloser, fuse, sectionalizing equipment, etc.(3) "Component" means a piece of equipment, a line, a section of line, or a group of items which is an entity for purposes of reporting, analyzing and predicting interruptions.(4) "Customer" means a separately-metered electrical service point for which a separate bill is rendered, i.e., each meter represents a customer.(5) "Customer interruption" means the loss of service due to a forced outage for more than five minutes, for one or more customers, which is the result of one or more component failures. For example, a downed house service is one interruption and a disconnected hot leg of a triplex house service, known as a "half-light" condition, is one customer interruption. However, failure of a transformer serving four customers is four customer interruptions.(6) "Customer interruptions caused by power restoration process" means when customers lose power as a result of the process of restoring power (such as from switching operations and fault isolation). The duration of these outages is included in the customer-minutes of interruption. However, only the customers affected by the power restoration outages that were not affected by the original outage are added to the number of customer interruptions.(7) "Customer-minutes of interruption" means the number of minutes of forced outage duration multiplied by the number of customers affected. For instance, a 90 minute forced outage on a circuit serving ten customers would total 900 customer-minutes of interruption.(8) "Electric distribution line" means circuits operating at less than 50,000 volts.(9) "Forced outage" means an outage which cannot be deferred.(10) "Major catastrophic events" means train wrecks, plane crashes, or explosions that are beyond the utility's control and result in widespread system damages causing customer interruptions that affect at least ten percent of the customers in the system or in an operating area and/or result in customers being without electric service for durations of at least 24 hours.(11) "Major storm" means a period of severe adverse weather resulting in widespread system damage causing customer interruptions that affect at least ten percent of the customers on the system or in an operating area and/or result in customers being without electric service for durations of at least 24 hours.(12) "Momentary interruption" means an interruption of electric service with a duration shorter than the time necessary to be classified as a customer interruption.(13) "Operating area" means a geographical sub-division of each electric utility's service territory that functions under the direction of a company office and may be used for interruption reporting under this part. These areas may also be referred to as regions, divisions, or districts.(14) "Outage" means the failure of a power system component that results in one or more customer interruptions.(15) "Outage duration" (reported in minutes) means the one minute or greater period from the initiation of an interruption to a customer until service has been restored to that customer.(16) "Partial circuit outage customer count" means where only part of a circuit experiences an outage, the number of customers affected is estimated, unless an actual count is available. When power is partially restored, the number of customers restored is also estimated. Most utilities use estimates based on the portion of the circuit restored.(17) "Planned outages" means those outages which the utility schedules. When customer service interruptions are necessary, the utility should notify affected customers in advance. These interruptions are sometimes necessary to connect new customers or perform maintenance activities safely. They shall not be included in the calculation of reliability indices. Note: Also see s. PSC 113.0502, Planned service interruptions.
(18) "Police actions" means request or order of police or fire officials to interrupt service due to an emergency.(19) "Reliability" means the degree to which electric service is supplied without interruption.(20) "Reliability indexes" include the following performance indices for measuring frequency and duration of service interruptions that have been developed by the Edison Electric Institute (EEI), the Institute of Electrical and Electronics Engineers (IEEE), the Canadian Electric Association (CEA) and the American Public Power Association (APPA). They are recognized as standard definitions for the electric utility industry and may be applied to entire distribution systems, operating areas, sub-operating areas or individual circuits. Customer interruptions attributed to major storms, major catastrophic events, or police actions, as defined herein, shall be included in the calculation of these indices throughout this standard. (a) System Average Interruption Frequency Index (SAIFI). The SAIFI index is the average number of interruptions per customer during a year. It is determined by dividing the total annual number of customer interruptions by the average number of customers served during the year. SAIFI = total number of customer interruptions
average number of customers served
(b) System Average Interruption Duration Index (SAIDI). The SAIDI index is the average customer-minutes of interruption per customer. It is determined by dividing the annual sum of customer-minutes of interruption by the average number of customers served during the year. SAIDI = sum of customer-minutes of interruption
average number of customers served
(c) Customer Average Interruption Duration Index (CAIDI). The CAIDI index is the average customer-minutes of interruption per customer interruption. It approximates the average length of time required to complete service restoration. It is determined by dividing the annual sum of all customer-minutes of interruption durations by the annual number of customer interruptions. CAIDI = sum of customer-minutes of interruption
total number of customer interruptions
Wis. Admin. Code Public Service Commission PSC 113.0602
CR Register, July, 2000, No. 535, eff. 8-1-00; CR 02-027: am. (8), Register December 2002 No. 564, eff. 1-1-03.