Mitigating Contamination Related Issues on T&D Equipment Lily Hoyer Simon Chan
Substation Insulator Pollution Contamination Management
PRESENTED BY LILY HOYER T&D ASSET MANAGEMENT ENMAX POWER CORPERATION Contents INTRODUCTION ENMAX INSULATOR FLASHOVER STATISTICS PRESENTED TO 2012 APIC POWER AND ENERGY INNOVATION FORUM MITIGATION MANAGEMENT PILOT PROJECT CONCLUSION
INTRODUCTION OF INSULATOR CONTAMINATION Insulator: isolation from the energized high voltage bus to ground Insulator pollution contamination 4
How does your car look in winter? Road salt on the car 5
INTRODUCTION OF INSULATOR CONTAMINATION Insulator flashover: surface discharge when moisture condenses on solid insulation subject to particulate pollution Factors of insulator flashover: Moisture condensation Pollution (By location) Industrial areas: fly-ash, variety of dust Agricultural areas: soil dust, fertilizers Highways: salt from roads during winter time By components: Soluble: Salt or Sodium Chloride Non-Soluble: Calcium Chloride, carbon, and cement dust ect. 6
INTRODUCTION OF INSULATOR CONTAMINATION Sequence of events leading to flashover Deposit of pollution on the insulator surface Surface layer is moistened by fog, misty rain Surface layer is heated Heating results in local drying and dry bands formed Partial arc occur across dry bands Increased partial discharge Partial discharges are connected to a complete flashover Video of the surface discharge 7
ENMAX EXPERIENCE OUTAGE STATISTICS CAUSED BY INSULATOR FLASHOVER 2008 with most interrupted customers and longest interruption duration Average Interruption time in minutes has significantly reduced since 2009 # of Customers Interrupted 90000 80000 70000 60000 50000 40000 30000 20000 10000 0 6 2 3 3 2 0 0 2007 2008 2009 2010 2011 2012 Year 70 60 50 40 Average Interruption 30 Duration (min.) 20 10 8
MITIGATION MANAGEMENT Time based preventive maintenance program Review and enhance our substation washing program (Sub washing committee was formed in 2008) Meets twice a year to review frequencies Analyzes past year s sub washing for effectiveness Corrective maintenance program Visual inspection Anticipation of the contamination (weather condition change) 9
SUBSTATION WASHING PROGRAM IN DETAIL Factors of determining sub washing frequency Location of the sub (near high way, industry, river, land elevation) Area external to the sub (construction, type of roads) Past history of insulator flashover Type of insulators (polymer, porcelain) Type of bus (H bus-water drainage) Insulator hats are installed (prevent water drops freezing from skirt to skirt) Criticality of the sub (control center input) Management and Field input 10
H bus vs. Round bus
Types of Insulator in Enmax Porcelain Silicone covered porcelain Polymer
Substation Washing types High pressure washing Flood washing Corn blast washing Hand wash
Washing Experience hand wash Scratches on silicone coated porcelain insulator by hand wash
Washing Experience Polymer seam Seam of polymer insulators introduced in manufacturing process
Substation Washing types vs. Insulator type High pressure washing Flood washing Corn blast washing Hand wash Porcelain Insulators Silicon coated Insulators Polymer Insulator
# of Substations Substation Wash Schedule Washing schedule 12 10 8 6 4 2 0 Distribution of Sub Washing Frequency 2/year 1/year 1/2 years 1/3 years 1/4 years Washing Frequency Ongoing review of the washing frequency
PILOT PROJECT DOBLE IPM Initialized in 2009 to utilize condition monitoring of pollution severity based on leakage current Installed Doble IPM in Fall 2010 on one substation next to highway and river
PILOT PROJECT DOBLE IPM Location
20 DOBLE IPM METHODOLOGY
21 LOCATION OF THE CURRENT SENSOR 138 kv
22 CURRENT SENSTOR MOUNTING LOCATION
23 DOBLE IPM METHODOLOGY
Evaluation of Pollution Level High cumulative charges + High peak currents (with high counts) High level of pollution Dry & polluted insulator -> lower peak current; Foggy, high humidity morning -> Flashover??? 24
Imax Calculation Maximum peak leakage current is defined as Imax= (SCD/15.32)^2 SCD_138 = 2514.6/145 = 17mm/kV SCD: Specific Creepage Distance in mm/kv KV is the maximum phase to phase voltage 138kV insulator: Creepage distance is 99 inch. Guideline for peak leakage current threshold value is set at 25% of Imax I_138_threhold = 308 ma (???) 25
DOBLE IPM LEAKAGE CURRENT MEASUREMENT Plot from Jan April 2012 26
DOBLE IPM LEAKAGE CURRENT MEASUREMENT March 15, 2012 Substation wash 27
Doble IPM EXPERIENCE Limitation in Leakage current method in Calgary winter (dry and heavy polluted insulator -> small leakage current) Benchmark is not available (Doble threshold value too high) Lack of Doble support 28
Conclusions Washing committee enhanced sub washing program: less flashover outages and duration of outage decreases Equipment upgrade is ongoing: H bus replacement, porcelain insulator replacement Leakage current detection: correlation to relative humidity, ESDD (equivalent salt deposit density) tests 29
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PRESENTED BY SIMON CHAN T&D ASSET MANAGEMENT ENMAX POWER CORPERATION I Contents EFFECTS OF CONTAMINATION PRESENTED TO 2012 APIC POWER AND ENERGY INNOVATION FORUM MITIGATION METHODS
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Effects of Contamination Effects of contamination include: Flash Over on Equipment (Equipment failure) Electrical Tracking (Wood Pins, Cross Arms) Pole Fires Material Failures (Automatic Sleeves) Exterior Rusting, peeling of paint. Consequences Poor reliability Safety $$$ 33
Equipment/Material Flashover Padmount Switchgear Rusting, peeling of paint on exterior. Higher risk of flashovers 34
Electrical Tracking Wood Pins Androlite Arms Wood Cross Arms Insulators 35
36 Wood Pin
37 Androlite Arms
Pole Fires Pole fires caused by contamination can only occur under the following conditions: Leakage current from energized equipment. Heat
Road Salt vs Pole Fires
MITIGATION METHODS Androlite Conversion Insulator Washing Switch Cleaning Material Standard Change Pole Fire Mitigation Program Wood Pin Program Padmount Painting/Exterior Replacement 40
Androlite Conversion Flattening Androlite Configuration to Current Construction Standards
Insulator Washing Maintenance Program EPC initiated a multi-year insulator washing maintenance program. Priority is on City of Calgary Priority One sanding routes. Extra emphasis on areas where pole fires occurred previously. Twice a year cycle. Late March to early April. Late September to early October
Insulator Washing Maintenance Program
Pad Mount Switch Dry Ice Cleaning Contaminants have caused flashovers to Live Front Pad Mount Switch Gear. EPC has implemented a 5 year inspection and dry ice cleaning cycle for switches. EPC is exploring possibilities of dry ice cleaning for Distribution Automation Pad Mounted Switches.
Material Standard Changes Porcelain to Polymer Porcelain insulators Over insulated 34 kv polymer insulators. Change to Porcelain Fused Cut Outs and lightning arrestors to Polymer. Cross Arms (Wood to Fiber glass) Fiber glass replaces deteriorated wood crossarms.
Material Standard Changes
Material Standard Changes
Material Standard Changes Cut Outs 48
49 Splices
Splices Automatic to Compression Sleeves Initial samples Corrosion found. Corrosion was more evident near major roadways. In 2011, only compression splices are to be used for all new construction and repair work. Ongoing further investigation of automatic splices. 50
Pole Fire Mitigation Program In 2001, EPC initiated a multi-year over-insulation and insulator washing maintenance program. A total of $.57M were spent in the next seven years (2001 2007). No structures that had been mitigated with upgraded insulation have been involved in pole fires.
Pole Fire Mitigation Program EPC has seen an increase in contamination of the distribution overhead structures. In 2008, there were 76 pole fire incidents causing nearly 96000 customer interruptions and significant customer interruption time.
53 Pole Fire Locations
Incidents Pole Fire Mitigation Program 80 Pole Fires 70 60 50 40 30 20 10 0 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 (YTD) Year
Pole Fire Mitigation Program Alternatives Considered 1) Do nothing 2) Dry Ice Washing 3) Bonding 4) Over Insulation
Pole Fire Mitigation Program Over Insulation Wood crossarm Fiberglass crossarm Porcelain insulator 34 kv class polymer insulator Porcelain cutout Polymer cutout
Pole Fire Mitigation Program
Pole Fire Mitigation Program Current Progress Primarily focus is on mitigating overhead structures with equipment only. Mitigated nearly 70% of these structures. Expected completion 2014.
59 POLES MITIGATED
Wood Pin Program Prevalent standard of insulator support until early 1970s when steel pins become industry standard. Increased risk to the safety of the general public and EPC employees. Minimize hazards.
Wood Pin Program Material Change Wood pins to Steel Pins Contamination due to road salt increased rate of deterioration in wood pins due to electrical tracking.
Wood Pin Program Started in 2008 Nearly 4000 Structures containing wood pin to replace. Expected completion in 2014.
Equipment Painting/Exterior Replacement Existing Padmount Painting Program Typically 2000-3000 pad mounted equipment a year. Severe deterioration Replacement of doors and tops 63
Questions?? Simon Chan, schan@enmax.com Lily Hoyer, lhoyer@enmax.com Change this under "View" menu, Header/Footer options