SF6 Leak Repair Case Study ConEd West 49th Street GIS Jonathan Brengel, ConEd Liisa Colby, The Colt Group

Agenda Station Overview SF6 Emissions Summary Leak Identification Repair History Alternative Solutions Repair Cost Issues Moving Forward The Leak Repair Process Other SF6 Repair Examples

Station Overview

Station Overview West 49th Street Substation reduces voltage from 345 kV to 138 kV Five 345 kV feeders Two from Sprain Brook Substation Two from East 13th Street Substation One inter-utility feeder from Public Service Electric and Gas Company Eleven 138 kV feeders from the station supply W 42nd St., W 50th St., W 65th St. and Astor Substations Gas Insulated Switchgear (GIS) at the station was put into service in 1978 No design requirements to control leakage were in place in 1978 Fifteen SF6 insulated 345 kV and 138 kV bus sections Five autotransformers Ten 345 kV circuit breakers

SF6 Historical Emissions 2,049 lbs. of SF6 Emissions from West 49th Street in Accounts for ~17% of total SF6 emitted for entire company in 2015 *Gas call data improvements were implemented during 2014 resulting in enhanced data accuracy during the 2nd half of 2014 onward Areas of greatest concern Transformer 3 secondary bus, Bus Section 3, Transformer 5 secondary bus 49th Street Substation SF6 Annual Emissions Summary   2014 2015 YTD Total SSO SF6 Emissions (lbs) 15,901 12,682 Total 49th Street (lbs) *1,576 2,049 % of Total SSO Emissions 9.91% 16.20%

SF6 Historical Emissions Transformer 3 Secondary Bus Section 24 gas calls in 2014 For each gas call a mechanic attempted to find a leak Average leak identification time of 4 hours x $85/man-hour x 24 gas calls = $8,160 366 lbs. SF6 emitted 2015 27 clamps, 8 bypasses and 9 patches on bus work currently *Gas call data improvements were implemented during 2014 resulting in enhanced data accuracy during the 2nd half of 2014 onward TR3 SF6 Annual Emissions Summary   *2014 2015 Total TR3 Secondary Bus (lbs) 421 366 Total Bus Section 3 (lbs) 263 217 Total TR5 Secondary Bus Section (lbs) 88 249

 Leak Identification & Sampling Techniques Minimize number of samples ZERO Purge SF6 Analysis Previously emitted 2 lbs per sample 500-700 lbs released per year New DILO SF6 gas analyzers Improved tool for leak detection FLIR GF306 SF6 Camera  11

49th Street Substation SF6 Repair Summary SF6 Leak Repair Status 94 100 35 49th Street Substation SF6 Repair Summary Total clamps installed (including on bypasses) Total bypasses Total patches Total Active leaks Clamp on leaking bypass in Transformer 3 Secondary Bus Clamp on leaking flange in Bus Section 7 Welded patch on secondary CCPD

Colt Clamp Temporary Repairs $263,000 in O&M spent in 2014 on clamps $324,000 spent in O&M already through September of 2015 Estimating $162,000 to be spent on clamps/repairs during remainder of year ~$4,000 to $15,000 per clamp Concern with added weight, structural integrity, bus failure, etc. Aluminum clamps may also be used - Lighter weight but more expensive Moving forward, all clamps require supports 2 year Warranty

Examples: Colt Clamp Repairs

Permanent Repairs Eliminate centralized gas fill system Remove clamps on leaking welds and re-weld/repair (outage required) Currently planning to remove 5 clamps and repair welds on TR5 secondary during fall outage NDE testing on patches/welds that aren’t clamped to identify possible future leak areas Replace temporary bypass piping clamps with stainless tubing and DILO self-sealing fittings

Equipment Replacement Install a circuit breaker on each 138 kV feeder leg (2 circuit breakers, disconnect switches, all buswork) Estimated at $2.3 million per each 138 kV section (equipment cost only) Maintain reliability advantages Replace a 345 kV Bus Section (circuit breaker, potential transformer, disconnect/ground switches, bus, LCC, adapter flanges and structures) Estimated at $1.75 million per bus section (equipment cost only) ~14 to 16 month delivery and installation

West 49th Street 2015 Annual SF6 O&M Costs Additional Costs West 49th Street 2015 Annual SF6 O&M Costs Item Total Cost Clamp Installation $486,000 SF6 Gas Added ($8.50/lb) $19,920 Daily Leak Locating/Repairs $180,000 Split TR Secondary Alarm Points $74,000 Install Supports on Existing Clamps $42,000 Fall Outage Leak Repairs $173,000 Chem Lab - Gas Sampling/Outage Support $29,400 TOTAL PROJECTED COST $1,004,320 *Project annual costs based on actual spent YTD

Issues Lack of O&M funding No long range plans to replace equipment and no plan for added capacity Limited availability for outages

Moving Forward How do we help meet future goals? 15,000 lbs. – 2015 (equivalent to 7% of nameplate) 14,000 lbs. – 2016 proposed goal 13,000 lbs. – 2017 proposed goal Continue to leverage capital programs Circuit Breaker Reliability Program SF6 GIS Bus Overhauls AGS Retirements SF6 Peer Management Team SSO/EH&S-Air/Chem Lab/Engineering/TLC Monthly meetings to keep lines of communication open Maintain focus, identify and work through issues together

The Leak Repair Process

Options for dealing with leaks: Let it leak If oil is getting out, air and moisture are getting in Re-gasket or replace Cost, outage time, resources required In-house Repair (Epoxy) Not always effective Use Outside Repair Specialists An alternative worth considering

No need to drain the oil or gas or depressurize Benefits of Online Leak Repair for HV App No need to drain the oil or gas or depressurize Many repairs can be made under pressure – energized The sealant is not an epoxy – it’s flexible and easily removed

Epoxy – can’t be easily removed Do-it-yourself Kit Common Misconceptions of Leak Repair It’s a band-aid What is temporary? Epoxy – can’t be easily removed Do-it-yourself Kit Concerns about the sealant

A Proven Process 15,323 jobs completed since 2002 6,286 Flanges 5,691 Valve packings 1,045 Custom clamps & enclosures 875 Drain plugs 287 Cover plates 91 Miscellaneous 38 Tap changer flanges 24 CTs 987 re-pumps over twelve years or 6.4%. A 93.6 success rate

The History of Online Leak Repair

Leak Sealing Today Pressures up to 7,500 psig Temperatures from Cryogenic to 1800 F

After 20+ Years of Experience

Oil Leak Flange Repair using “Drill & Tap” injection

About The Sealant Independent Lab Report Results: Dissolved Gas in Oil (DGA) Dielectric strength Minus 40 degrees C/F – 40 degrees C/F Sealant is NOT an epoxy - It’s flexible and easily removed.

Manufacturer Warranty TC Flange Repair Sealant injected via Injectable Bolts Repair made with unit in service

Custom Clamps & Enclosures Thread Leak on Valve (Bar Clamp) 33

Alliant Energy Eddyville Substation 69 kv SF6 Breaker Eddyville, Iowa SF6 Leak Repair Example Alliant Energy Eddyville Substation 69 kv SF6 Breaker Eddyville, Iowa

Client options Let it leak. Not an option, environmental concern Re-gasket. Time to take the breaker out of service was the primary issue. Would require 5 days of down time, loss of transmission and $20,000.00 in costs Leak Repair – Installing custom enclosure and injecting sealant. Determined the optimal solution Justification: Reduced downtime for critical apparatus. Just 1 day of down time and $20,860.00 to fix all leaking components Savings = 4 days of transmission

SF6 Circuit Breaker - Casting Leak .

SF6 Circuit Breaker - Casting Leak SF6 Leaks SF6 Circuit Breaker - Casting Leak

Ongoing Research….

Clamp Removal

Sealant Removal

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