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Substation Inspection Program
Mission Substation IncidentMission Substation Incident
The event occurred on December 20, 2003 during the peak Christmas shopping season
A fire occurred in a 12kV cable feeding a switch on the second floor of a 3 story indoor substation
The substation receives power from 115kV underground cables and distributes 4 and 12kV within SF
The fire caused a complete outage of the substation, effecting about 100,000 customers, some for as long as 32 hours
Timeline
15:51—The network cable failed explosively. No customers lost power
15:51—A circuit breaker protecting the “N” bus also operated
17:24—The fire migrated to a bus duct above the switch and the burning bus caused the circuit breaker protecting another switch cabinet to operate, causing an outage to 3112 customers
Timeline
17:42—A switchman was sent to Mission substation to investigate the incident
17:57—All transmission circuit breakers were opened, causing an outage to approximately 100,000 customers
Section of Damaged “N” Bus
The Damaged Cable
Investigation
CPUC assembled a team of engineers, analysts and attorneys to investigate the incident.
During one of the interviews, the CPUC asked if there had been any previous incidents at Mission Substation involving fire.
Yes, a previous incident occurred in 1996. The incident was very similar to the fire that
occurred in 2003.
Mission Substation Incident-1996
A vertically installed PILC cable caught on fire Smoke from that fire caused a short across the
“N” bus Around 1:00am, a PG&E employee went to
the substation to use a restroom and discovered the fire.
Mission Substation Incident-1996
Three key recommendations from that investigation were:
Initiate fire penetration sealing program between floors.
Review procedures for responding to abnormal operating conditions, such as circuit breaker trips
Evaluate a cost effective method of smoke detection.
Mission Substation Incident
PG&E did not implement any of the key recommendations at Mission Substation by the time the incident occurred in 2003.
CPUC published its report CPUC moved toward an Order Instituting
Investigation (OII)
Mission Substation Incident
PG&E disputed our finding that the remedial measures would have made a difference.
PG&E decided to settle the dispute via the Mission substation settlement agreement.
Settlement
PG&E, the City and County of San Francisco and the CPUC agreed that PG&E will pay $6.5 million, to various causes: $500,000 to the States General Fund $3.0 million for reliability improvements to PG&E $750,000 for a fire safety program for SFFD $750,000 for CCSF to build needed infrastructure to
improve public safety $1.0 million for a Hunters Point Substation Improvement
Program $500,000 to support the Commission’s undertaking to
create a substation inspection program.
Creation of Inspection Program
Meet with Five Investor Owned Utilities (PG&E, PP&L, SCE, SDG&E & SPP)
Attended Training and Conferences concerning Substations and Equipment
Attended CAISO audits of Utility’s Substation Programs
Two Choices
Prescriptive Benefits
Easy to Audit Easier to Understand Easily defined criteria
Problems May require work to be
done that is not needed Does not account for
differences
Performance Benefits
Gives utilities flexibility Accounts for differences
Construction Environment Operation
Problems Harder to audit
Picked Middle Ground
Proposed General Order has both Prescriptive Parts and Performance Based Parts
The Proposed General Order(As written today)
Six Sections General Provisions Definitions / Acronyms Construction Requirements Operation and Maintenance Program Reporting Requirements Maps and Drawings
13 pages
Section IGeneral Provisions
Purpose Applicability Scope of Rules* Investigation of
Accidents Saving Clause
“These rules are not intended as complete construction, inspection, or maintenance specifications, but embody only the minimum requirements which are most important from the standpoint of safety and reliability of service.”
Section IIDefinitions / Acronyms
Defines key terms used throughout the general order
Example“Visual Inspections” are inspections that are designed to identify obvious problems and hazards.
Section IIIConstruction Requirements
General Provisions Guarding Marking Safety Factor Requirements Secondary Oil Containment Switches
Section IVOperation and Maintenance Program
General Provisions
Inspection Procedures
Maintenance Procedures
Section VReporting Requirements
Operation and Maintenance Plan – Utilities must file a copy of their Operation and Maintenance Plan yearly
CPSD Audits – Pre Inspection Report due 30 Calendar Days before Audit
Section VIMaps and Drawings
Types of Maps and Drawings
Single Line Diagram Meter and Relay
Drawing Physical Layout (e.g.
Architectural drawings)
Map/Drawing Updates
180 Days
Creation of Inspection Program(The Future)
Before an OIR is opened will meet with: Electric Utilities Rail Transit Agencies
Legal Review of the Proposed General Order Open an OIR –
Workshops Briefings Hearings???
Start Inspections
Questions