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