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Pilot Program on the Application of Electronic Resettable Sectionalizers to

Improve Reliability

SWEDE ConferenceMay 1, 2008

Van NguyenThu-Van.Nguyen@CenterPointEnergy.com

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Pilot Program Review

• Circuit History on Hockley (HK) -04 and -06– Circuit Demographics– Reliability Performance

• Root Cause Analysis on Circuit Operations and Fuse Outages– Review of Outage Data in Early 2005– Potential Solutions

• Course of Action for Electronic Resettable Sectionalizers (ERS )– Functions– Advantages– Safety Concerns– Implemented by Early 2006– Education

• Performance Results for 2006 and 2007

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Circuit History

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HK-04 Lateral

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Circuit History (con’t)

• Reliability Performance on HK-04– 10% SAIDI circuit in 2003, 2004 and 2005– Excessive circuit operations in 2004– 9 specific fuses accounted for 60% of total

circuit SAIDI minutes from potential temporary events (lightning, wind, wildlife, etc…) in 2004

– Similar performance in 2003 and 2005

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Circuit History (con’t)

• Reliability Performance on HK-06– 10% SAIDI circuit in 2004 and 2005– Excessive circuit operations in 2004– 5 specific fuses accounted for 58% of total

circuit SAIDI minutes from potential temporary events in 2004

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Root Cause Analysis

• Review of Outage Data in Early 2005– 60% (HK-04) and 58% (HK-06) of total circuit SAIDI

mins from potential temporary events in 2004– Excessive circuit operations in 2004

• HK-04 – 27 operations• HK-06 – 36 operations

– Source of excessive operations unknown– Fault current data ( < 1kA to > 4kA ) from relays

indicated activities may be at multiple points

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Root Cause Analysis (con’t)

• Review of Outage Data in Early 2005– Lightning analysis investigation

• No static construction• Flat, grasslands, agricultural areas• Temporary events such as lightning and wind• Erratic fault current values• Correlation between outages and lightning strikes

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Mapping of Hockley Circuits

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Lightning Data Plot for 2004

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Root Cause Analysis (con’t)

• Investigation of Potential Solutions– Installation of lightning arresters

• Effective but costly– Installation of static neutral

• Effective but costly– Remote controlled equipment

• Limited effectiveness– Electronic resettable sectionalizers (ERS)

• Effective and economical

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Course of Action

• Functions of ERS Devices– Works in conjunction with upstream reclosing

protective device– Similar in operation as a typical sectionalizer

• Registers current greater than its actuating level• Registers loss of voltage • Device opens on predetermined number of counts of

fault current AND loss of voltage– 1, 2 and 3-count devices can be placed in series

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Course of Action (con’t)

• Advantages of ERS Devices– Allow temporary faults to clear without

experiencing a sustained interruption– Less expensive alternative to reclosers to isolate

faulted (sustained) sections of conductor– Fits into standard fuse cutout body– Simple to install and implement– Ideal for replacing existing fuses

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Course of Action (con’t)

• Safety Concerns on ERS Devices– Must be used in conjunction with an upstream

reclosing protective device– Cannot be blindly used to replace fuses– Detailed engineering analysis must be

performed prior to implementing– Lack of familiarity by line crews on the

operation of ERS devices

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Course of Action (con’t)

• Implemented by Early 2006– Protection analysis conducted by engineering– Breaker coordination with hydraulic reclosers– HK-04

• 3 hydraulic reclosers installed• 9 fuses replaced with ERS devices

– HK-06• 1 hydraulic recloser installed• 5 fuses replaced with ERS devices

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Hockley-04 Oneline

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Recloser 127Z

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Sectionalizer 112N

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Hockley-06 Oneline

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Course of Action (con’t)

• Education– Line crews trained on application– Article published in company-wide newsletter– Stenciling nomenclature (###N or N###)

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Stenciling Nomenclature

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Performance Results for 2006

• HK-04 and HK-06 – 47% combined decrease in SAIDI values– Neither repeated as 10% SAIDI circuits

• Pilot program deemed successful• CPE approved the deployment of ERS

devices on other circuits

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Performance Results for 2007

• HK-06 was not a 2007 10% SAIDI circuit

• HK-04 was a 2007 10% SAIDI circuit– 16% of total circuit SAIDI mins from potential

temporary events behind line fuses– Trees, collisions, material failures and unknown

causes also contributed to SAIDI mins

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Questions?