CAUSE AND PREVENTION OF HUMAN ERROR IN ELECTRIC UTILITY OPERATIONS - SPP

CAUSE AND PREVENTION OF HUMAN ERROR IN ELECTRIC UTILITY

OPERATIONS

Terry Bilke

Midwest ISO

ABSTRACT

Trends in the electric utility industry have increased the chances and costs of errors by power system

operators. Competition is dictating that more be done with available assets. There are fewer field personnel.

Cost, rather than reliability and ease of operation is taking priority in new power distribution equipment.

Computers, which can be used to simplify work , are installed primarily to process more information and allow

the operator to do more.

Although this study touches on many aspects of electric operations, it focuses on errors committed by

the people running the nerve center of the industry, the power system dispatchers or operators. By the nature of

the job, these people are the most visible when something goes wrong. The effects of their mistakes are

immediate and potentially costly. This is in contrast with engineering or management mistakes which might

never be detected even though things later goes awry because of them.

Even though errors are taken seriously by the industry, little has been done to formally track and reduce

their occurrence. The two cases found relied on the principle that lack of concentration was the primary cause of

mishaps. In other words, the dispatcher must be "fixed" if the situation is to improve. This theory is in contrast

with other process industry and manufacturing approaches to prevent errors, defects and accidents.

This study started with a survey of dispatchers from 18 utilities representing nearly 2000 years of

operating experience. Operators identified underlying error causes and suggested improvements. In addition,

other fields were examined to find ways to track and reduce errors. Quality management and reliability

engineering principles were found that apply to error reduction. The cognitive science and industrial safety

professions also have concepts that prove useful in understanding and eliminating mistakes.

This paper should provide a better understanding of human error. It is intended to give practical

information to operating personnel. It offers suggestions, tools and a plan that any utility can use to reduce the

likelihood of errors in its control centers, power plants and out in the field.

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It's been said that those who cannot remember the past are doomed to repeat it. If we learn from others,

we need not commit the same mistakes. Not only must dispatchers learn from their coworkers, but companies

should share information for everyone's benefit. That is why this paper also recommends the establishment of a

utility error database.

Terry Bilke

Midwest ISO

701 City Center Drive

Carmel, IN 46032

317/249-5463

tbilke@

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CAUSE AND PREVENTION OF HUMAN ERROR IN ELECTRIC UTILITY

OPERATIONS

TABLE OF CONTENTS

INTRODUCTION .................................................................................................................................. 1

BACKGROUND ....................................................................................................................................... 1

WHAT CAN BE DONE? ........................................................................................................................... 2

INCREASED CONCERN ............................................................................................................................ 2

OBJECTIVES .......................................................................................................................................... 3

SIGNIFICANCE ....................................................................................................................................... 3

OPERATING ERROR OVERVIEW ............................................................................................................... 4

TYPES OF SWITCHING OR OPERATING ..................................................................................................... 5

Scheduled Switching ......................................................................................................................... 5

Routine Switching............................................................................................................................. 6

Unscheduled Switching..................................................................................................................... 6

Emergency or Forced Switching ....................................................................................................... 7

TRENDS IN THE SYSTEM OPERATOR JOB ................................................................................................. 7

Competition and the FERC............................................................................................................... 8

Computers ........................................................................................................................................ 8

CHANGES IN THE OPERATORS ................................................................................................................. 9

COGNITIVE SCIENCE AND THE THEORY OF ERROR.............................................................. 10

INTRODUCTION.................................................................................................................................... 10

Problems Defining Errors............................................................................................................... 10

Problems with Error and Safety Data ............................................................................................. 10

Difficult to Quantify Error Costs .................................................................................................... 11

Myths Associated with Errors ......................................................................................................... 11

ERRORS ARE MULTIDIMENSIONAL ........................................................................................................ 12

ERROR CLASSIFICATIONS AND DEFINITIONS .......................................................................................... 13

Two Broad Categories .................................................................................................................... 14

Definitions...................................................................................................................................... 14

Importance of Operating Error Definition ...................................................................................... 15

LEVELS OF PERFORMANCE ................................................................................................................... 15

Skill Based Performance................................................................................................................. 16

Rule Based Performance................................................................................................................. 16

Knowledge Based Performance....................................................................................................... 17

Performance Levels Applied to Operations ..................................................................................... 17

MAJOR ERROR TYPES .......................................................................................................................... 18

Slips ............................................................................................................................................... 18

Lapses or Omissions ....................................................................................................................... 22

Rule Based Mistakes....................................................................................................................... 23

Knowledge Based Mistakes............................................................................................................. 24

Violations ....................................................................................................................................... 26

Latent Errors .................................................................................................................................. 27

ERROR DETECTION .............................................................................................................................. 28

Performance Level Summary .......................................................................................................... 30

HUMAN ACTION MODEL ...................................................................................................................... 31

Background .................................................................................................................................... 31

Components.................................................................................................................................... 32

Human Variability .......................................................................................................................... 36

Problems in Complex Systems......................................................................................................... 37

How People Make Observations ..................................................................................................... 38

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Problems with Communication ....................................................................................................... 39

INDUSTRY'S PERSPECTIVE ON HUMAN FAILURE ................................................................... 42

INTRODUCTION.................................................................................................................................... 42

QUALITY CONTROL/QUALITY MANAGEMENT ....................................................................................... 42

Who is Responsible for Errors? ...................................................................................................... 42

Two Types of Errors or Defects....................................................................................................... 43

Process Variation and Improvement ............................................................................................... 46

Human Error and Remedies from a Quality Perspective ................................................................. 47

Useful Quality Control/Quality Management Tools ........................................................................ 48

HUMAN RELIABILITY ........................................................................................................................... 50

Error Estimates .............................................................................................................................. 51

INDUSTRIAL SAFETY ............................................................................................................................ 53

Who Contributes to Errors in Other Industries?.............................................................................. 54

Accident Frequency ........................................................................................................................ 55

Accident Reports and Analysis........................................................................................................ 56

SURVEY RESULTS............................................................................................................................. 59

INTRODUCTION.................................................................................................................................... 59

THE SURVEY ....................................................................................................................................... 59

CAUTIONS INTERPRETING THE DATA .................................................................................................... 60

SUMMARY RESULTS ............................................................................................................................. 60

ERROR RATE ....................................................................................................................................... 61

REPORTED ERROR CAUSES ................................................................................................................... 61

ERRORS VS. WORKLOAD ...................................................................................................................... 62

Survey Response ............................................................................................................................. 64

Related Study.................................................................................................................................. 64

ERRORS VS. THE USE OF PLANNERS ....................................................................................................... 66

ERRORS VS. COMPANY SIZE ................................................................................................................. 67

ERRORS VS. EXPERIENCE ..................................................................................................................... 68

Related Study.................................................................................................................................. 69

ERRORS VS. TRAINING ......................................................................................................................... 69

SHIFT SCHEDULE-ERRORS VS. DAY OF THE WORKWEEK ........................................................................ 69

Alternate Analysis........................................................................................................................... 70

Related Study.................................................................................................................................. 71

Conclusions .................................................................................................................................... 72

SHIFT SCHEDULE-ERRORS VS. TIME OF DAY.......................................................................................... 73

Cognitive Science ........................................................................................................................... 73

Other Study .................................................................................................................................... 75

SURVEY ESTIMATE ON SLIPS (OPERATING THE WRONG DEVICE)............................................................ 75

COMMUNICATIONS PROBLEMS ............................................................................................................. 76

AUTOMATIC DEVICES OPERATING UNEXPECTEDLY (TRAPS) .................................................................. 76

PROCEDURE AND MAP ERRORS............................................................................................................. 76

THE SWITCHING PROCEDURE WAS WRITTEN INCORRECTLY ................................................................... 76

UNSCHEDULED JOBS ............................................................................................................................ 76

DISTRACTIONS .................................................................................................................................... 76

OTHER ................................................................................................................................................ 77

LINKS BETWEEN ERROR CATEGORIES ................................................................................................... 77

TROUBLE AREAS FOR NEW AND EXPERIENCED OPERATORS ................................................................... 77

EPRI SWITCHING SAFETY STUDY ........................................................................................................ 78

SHARING INFORMATION ....................................................................................................................... 79

IMPROVING OPERATIONS ............................................................................................................. 81

ERROR ANALYSIS ................................................................................................................................ 81

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