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Fault Location, Testing & Tracing:

“How to Avoiding Unplanned Outages”

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Moderator n  Ron Spataro

AVO Training Marketing Manager

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Q&A n  Send us your

questions and comments during the presentation

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Today’s Presenter n  Mark Franks

•  AVO Training Institute, •  Senior Cable Instructor and Curriculum Advisor

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Current Cable Status n  U.S. plagued with cable outages n  Cable systems nearing end of life n  Studies reveal poor workmanship n  Lack of training connected to

failures n  Lack of up to date fault locating

techniques n  Inadequate/no diagnostic testing

programs

Estimate of the Size of the Cable Technologies

Installed on U.S. Utility Systems

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Types of Cables

EPR

XLPE

Secondary

Three Phase PILC

Understanding Cable Components

Underground Residential Distribution

Shielded

Cable Component Function

■  Conductor- carries the load ■  Strand Shielding-prevents corona in conductor/smooth surface ■  Insulation- provides voltage rating ■  Insulation Shielding (Non-Metallic & Metallic)-equal electrical

stress for insulation ■  Bedding Tape- binds wire shielding strands ■  Jacket- provides protection for cable during and post installation

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Cable Splices n  Requires expert workmanship n  Numerous technologies available n  Represents majority of outages n  Affected by environment

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Importance of Cable Prep

■  Preciseness ■  Clean surfaces ■  Exact components

Electrical Stress Distribution in Splice

Molded Spice Installation

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Power Cable Termination n  Required for connecting to equipment

n  Provides method to terminate conductive shielding a distance from exposed conductor end

n  Provides tracking and flashover protection

n  Distance from conductor end to shield referred to as creepage distance

n  Requires similar workmanship level as spicing

Power Cable Termination without Stress Relief Cone

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Power Cable Termination

n  Stress relief cone provides stress relief. n  Can be hand-taped, preformed, or High-K material .

n  Electrical stress is reduced by employing the use of a stress cone.

Power Cable Termination with Stress Relief Cone

96-0314-1

Heat Shrink Class I Termination

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Conditions Causing Cable Faults n  Most often poor workmanship

n  NEETRAC conducted by Georgia Institute of Technology indicates 42.7% outages due to faulty splices and terminations

n  Many cable failures are caused by damage during installation by improper pulling and handling

n  Defects inherent with manufacturing process

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Estimated North American MV Cable System Failures by Equipment Type

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Typical Power Cable Defects That Cause Failure

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Cable Failures

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Termination Failure n  Failure due to poor workmanship

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Cable Fault Location n  Identifying faulted cable n  Tracing cable path n  Secondary fault locating n  Time Domain Reflectometer n  Thumper/Tracer/Arc Reflection n  Test after repairs

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Cable Identification n  Safety n  Poly phase n  Time saver

FIGURE 14Use of the Flexible Clamp

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Locating

■  Reduces cost ■  Minimizes outage time ■  Enables magnetic

trace ■  Increases accuracy

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Secondary Fault Locating

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Earth Gradient

Fault Tracing

Time Domain Reflectometer

■  Used for localizing ■  Locates opens and

shorts ■  Distance ■  Technology used in

conjunction with thumper for arc reflection

Illustration of a Pulse Propagating along a Cable

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Thumper/Tracer/Arc Reflection

n  Thumper n  Magnetic/Acoustical Trace n  Arc Reflection

Thum

per

0 16 kVolts

Thumper is connected Start to raise voltage

Breakdown! Note the breakdown voltage

8 4 12

Fault Location Process Breakdown Test

Thum

per

Thumper Operation

Charge up capacitor in thumper

Release HV Pulse onto cable HV Pulse reaches fault and creates an arc EM pulse and sound pulse emitted

EM pulse and sound wave travel at different speeds

Magnetic and Acoustical Tracing

Thum

per

On Screen

LV Pulse already captured Charge capacitors in Thumper Release energy through “Choke” filter HV pulse creates arc, LV pulse reflects off Electronics calculate distance to fault

Real Trace

Arc Reflection

fault

end

Pre-Location with HV Cable Fault Locator

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Test After Fault Repair n  Increases reliability n  Overall reduces costs n  Recommend VLF test

VLF Test Values

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Need for Training

n  Worker safety is the priority n  Significant work practices and procedures n  Vast array of technologies n  Training substitute for lack of tenure

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Summary n  US companies can expect fault location to be a significant

part of operations and maintenance

n  Cable outages will continue to plague the industry

n  Modern fault locating equipment, trained technicians and the practice of testing after repairs should improve reliability

n  Better efficiency and accuracy in fault locating can be achieved by more comprehensive training in a “real world” environ

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Hands-On Cable Training

n  AVO Cable U was designed as a technologically advanced “real world” place for every electrical cable installation, testing and diagnostic application.

n  Medium-Voltage Cable Technician Certification: •  Cable Splicing & Terminating, Medium-Voltage, •  Cable Fault Location & Tracing, Medium-Voltage

§  Medium-Voltage Cable Diagnostics & Testing: •  Certification Cable Testing & Diagnostics, Medium-Voltage

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Save the Date for Our Next Webinar

Tuesday September 19, 2017 at 1pm – 2pm CDT

“Electrical Cable Safety: Switching and Clearing, Grounding and Test Area Protection”

Presented by: Mark Franks, AVO Training Institute, Senior Cable Instructor and Curriculum Advisor

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Questions? After more than 50 years, AVO Training remains a global leader in safety and maintenance training for the electrical industry. We deliver an engaging, hands-on experience for our clients in a professional, real-world environment. We strive to provide industry relevant courses in a practical and flexible learning environment through an ongoing commitment to quality service, integrity, instruction, and client satisfaction. Our goal is to convey practical job skills and career development for our clients and students by saving lives through a world-class learning experience.