Frequency of Maintenance Tests

NETA recognizes that the ideal maintenance program is reliability-based, unique to each plant and to each piece of equipment. In the absence of this information and in response to requests for a maintenance timetable, NETA's Standards Review Council presents the following time-based maintenance schedule and matrix.

One should contact a NETA Full-Member company for a reliability-based evaluation.

The following matrix is to be used in conjunction with NETAÕs Frequency of Maintenance Tests table. Application of the matrix is recognized as a guide only.

Specific condition, criticality, and reliability must be determined to correctly apply the matrix. Application of the matrix, along with the culmination of historical testing data and trending, should provide a quality electrical preventive maintenance program.

MAINTENANCE FREQUENCY MATRIX
 

EQUIPMENT CONDITION

POOR

AVERAGE

GOOD

EQUIPMENT RELIABILITY REQUIREMENT

LOW

1.0

2.0

2.5

MEDIUM

0.50

1.0

1.5

HIGH

0.25

0.50

0.75

Based on the table and the following equipment schedule, equipment in average condition with good reliability would be tested and serviced as follows:

                                Main switchgear                              Every 3 Years

                                Transformers Dry Type                   Every 3 Years

                                Metal Enclosed Busways                   Every 3 Years

                                Low Voltage Air Switches                 Every 4-5 Years

                                Low Voltage Molded Case Breakers    Every 4-5 Years

                                Protective Relays                             Every 1.5 Years

                                Ground Fault Relay Systems             Every 1.5 Years

                                A. C. Motors                                  Every 3 Years

                                M. C. C. Low Voltage                     Every 3 Years

APPENDIX B (cont.)

Inspections and Tests

(Frequency in Months)

Multiplier for Inspections and Tests

(Multiply Value by Matrix)

Section

Description

Visual

Visual & Mechanical

Visual & Mechanical & Electrical

7.1

Switchgear & Switchboard Assemblies

12

12

24

7.2

Transformers

7.2.1.1

Small Dry-Type Transformers

2

12

36

7.2.1.2

Large Dry-Type Transformers

1

12

24

7.2.2

Liquid-Filled Transformers

1

12

24
 

Sampling

 -

 -

12

7.3

Cables

7.3.2

Low-Voltage Cables

2

12

36

7.3.3

Medium- and High-Voltage Cables

2

12

36

7.4

Metal-Enclosed Busways

2

12

24
 

Infrared Only

 -

 -

12

7.5

Switches

      

7.5.1.1

Low-Voltage Air Switches

2

12

36

7.5.1.2

Medium-Voltage Metal-Enclosed Switches

 -

12

24

7.5.1.3

Medium- and High-Voltage Open Switches

1

12

24

7.5.2

Medium-Voltage Oil Switches

1

12

24

7.5.3

Medium-Voltage Vacuum Switches

1

12

24

7.5.4

Medium-Voltage SF6 Switches

1

12

24

7.5.5

Cutouts

12

24

24

7.6

Circuit Breakers

7.6.1.1

Low-Voltage Insulated-Case/Molded-Case CB

1

12

36

7.6.1.2

Low-Voltage Power CB

1

12

36

7.6.1.3

Medium-Voltage Air CB

1

12

36

7.6.2.1

Medium-Voltage Oil CB

1

12

36
 

Sampling

 -

 -

12

7.6.2.2

High-Voltage Oil CB

1

12

12
 

Sampling

 -

 -

12

7.6.3.1

Medium-Voltage Vacuum CB

1

12

24

7.6.4.1

Extra-High-Voltage SF6

1

12

12

7.7

Circuit Switchers

1

12

12

7.8

Network Protectors

12

12

24

APPENDIX B (cont.)

Inspections and Tests

(Frequency in Months)

Multiplier for Inspections and Tests

(Multiply Value by Matrix)

Section

Description

Visual

Visual & Mechanical

Visual & Mechanical & Electrical

7.9

Protective Relays
 

Electromechanical

1

12

12
 

Electronic

1

12

12

7.10

Instrument Transformers

12

12

36

7.11

Metering Devices

12

12

36

7.12

Regulating Apparatus

7.12.1.1

Step-Voltage Regulators

1

12

24
 

Sample Liquid

 -

 -

12

7.12.1.2

Induction Regulators

12

12

24

7.12.2

Current Regulators

1

12

24

7.12.3

Load-Tap-changers

1

12

24
 

Sample Liquid

 -

 -

12

7.13

Grounding Systems

2

12

24

7.14

Ground-Fault Protection Systems

2

12

12

7.15

Rotating Machinery

      

7.15.1

AC Motors

1

12

24

7.15.2

DC Motors

1

12

24

7.15.3

AC Generators

1

12

24

7.15.4

DC Generators

1

12

24

7.16

Motor Control

7.16.1.1

Low-Voltage Motor Starters

2

12

24

7.16.1.2

Medium-Voltage Motor Starters

2

12

24

7.16.2.1

Low-Voltage Motor Control Centers

2

12

24

7.16.2.2

Medium-Voltage Motor Control Centers

2

12

24

7.17

Adjustable Speed Drive Systems

1

12

24

7.18

Direct-Current Systems

7.18.1

Batteries

1

12

12

7.18.2

Battery Chargers

1

12

12

7.18.3

Rectifiers

1

12

24

7.19

Surge Arresters

7.19.1

Low-Voltage Devices

2

12

24

7.19.2

Medium- and High-Voltage Devices

2

12

24

APPENDIX B (cont.)

Inspections and Tests

(Frequency in Months)

Multiplier for Inspections and Tests

(Multiply Value by Matrix)

Section

Description

Visual

Visual & Mechanical

Visual & Mechanical & Electrical

7.20

Capacitors and Reactors

7.20.1

Capacitors

1

12

12

7.20.2

Capacitor Control Devices

1

12

12

7.20.3.1

Reactors - Dry-Type

2

12

24

7.20.3.2

Reactors - Liquid-Filled

1

12

24
 

Sampling

 -

 -

12

7.21

Outdoor Bus Structures

1

12

36

7.22

Emergency Systems

7.22.1

Engine Generator

1

2

12
 

Functional Testing

 -

 -

2

7.22.2

Uninterruptible Power Systems

1

12

12
 

Functional Testing

 -

 -

2

7.22.3

Automatic Transformer Switches

1

12

12
 

Functional Testing

 -

 -

2

7.23

Telemetry/Pilot Wire SCADA

1

12

12

7.24

Automatic Circuit Reclosers and Line Sectionalizers

  

7.24.1

Automatic Circuit Reclosers, Oil/Vacuum

1

12

24
 

Sample

 -

 -

12

7.24.2

Automatic Line Sectionalizers, Oil

1

12

24
 

Sample

 -

 -

12

7.27

EMF Testing

12

12

12