Con Edison of New York FFR PPE TESTING

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2007 APPA Engineering and Operations Technical
Conference Atlanta, Georgia April 13-18,
2007 Nailing the Basics Earns Princeton, IL RP3
Diamond Award Jason Bird City of Princeton,
IL Ron Till SC Electric Company April 16, 2007
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Background
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Background

• County Seat of Bureau County Illinois
• Area about 7.0 mi2
• Population about 7,500 (2000)
• City Owned Electric and Telecom Utilities
• 19 Electrical and Power Plant Employees

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Background

• Approximately 4,300 Customers
• 12 distribution circuits
• 70 overhead line
• 30 underground

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Background

• Receives bulk power at 138 kV
• 2 major substations
• 138 kV gt 34.5 kV and 12.47 kV
• 34.5 kV gt 12.47 kV and 2.4 kV
• Eight (8) multi-fuel engine-generators sets
• Used for summer peak shaving or export

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The Challenge

• Major substation upgrade planned, but City didnt
  have proper information to specify equipment or
  implement protection settings
• Short-circuit study required
• Coordination study required

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The Challenge

• Nearly 80 of the time transformer primary fuse,
  line fuse, and feeder breaker would operate
• No reclosing relay on feeder breakers meant
  extended outages to Customers for transient
  faults
• Need to improve reliability to Customers

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The Solution

• SC engineers spent 2 days in the field
  collecting data for the studies.
• Nameplate information
• Line conductor sizes, configurations and lengths
• Verified existing system maps
• Review existing transformer and line fusing
  practices

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The Solution

• An accurate model of the Citys distribution
  system was constructed
• Ran short-circuit studies in compliance with ANSI
  C37 standards to evaluate fault currents with and
  without generation
• Conducted coordination studies with and without
  influence of generation

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Study Results

• Indicated that the overcurrent protective devices
  were applied within their ratings with 38 MW of
  local generation off-line, but...
• Fault currents on the 12.47 kV system exceeded 18
  kA (sym.) when on-line
• Existing OCBs in station and distribution class
  cutouts potentially over-dutied

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Study Results

• New breakers in substation would cover the
  interrupting ratings while generation was
  on-line.but devices beyond substation would not
• Coordination study confirmed that high available
  fault currents made coordination with existing
  devices difficult

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Proposed Changes

• Evaluate ratings of distribution class cutouts
• City was already using Positrol Fuse Links, so
  for purposes of establishing interrupting
  ratings, assumed Type XS Open Cutouts had been
  applied universally on system
• Largest fuse link in inventory was 100 Amperes,
  so two styles of cutouts to choose from

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Proposed Changes

• Type XS Fuse Cutout
• Extra-Heavy-Duty Style
• 100 A Max.
• 14.4/15.0 kV Nom./Max.
• 110 kV BIL
• 12.0 kA, Asym.
• 8.6 kA, Sym.
• one-shot rating, based upon replacement of
  cutout tube

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Proposed Changes

• Type XS Fuse Cutout
• Ultra-Heavy-Duty Style
• 100 A Max.
• 14.4/15.0 kV Nom./Max.
• 110 kV BIL
• 16.0 kA, Asym.
• 10.6 kA, Sym.

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Proposed Changes

• With generators off-line, Extra-Heavy-Duty Style
  cutouts were capable of interrupting fault
  currents on any feeder when they were placed a
  minimum of 1,000 circuit-feet away from the
  substation
• Considered fault duty and X/R ratio
• ANSI C37.42-1996
• EHD tested at X/R 8
• UHD tested at X/R 12

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Proposed Changes

• However, when the generators are on-line, the
  available fault currents are too high.need to go
  with Ultra-Heavy-Duty Style cutouts or even Power
  Fuses close to or in the substation

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Proposed Changes

• SMD-20 Power Fuse
• Overhead-Pole Top Style
• 200 A Max.
• 17.0 kV Max.
• 110-150 kV BIL
• 22.4 kA, Asym.
• 14.0 kA, Sym.

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Proposed Changes

• SMD-40 Power Fuse
• Station-Vertical Style
• 400 A Max.
• 17.0 kV Max.
• 110 kV BIL
• 40.0 kA, Asym.
• 25.0 kA, Sym.

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Proposed Changes

• Fault Tamer Fuse Limiter
• 20 A Max.
• 15.0 kV Max.
• 110-125 kV BIL
• 12.0 kA, Sym.
• 15,700 Max. I2t

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Proposed Changes

• Listed the minimum number of circuit-feet and
  geographic locations for the application of each
  type of device with the generators on-line

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Benefits

• Protective devices applied within ratings
• Standardization of protective devices / switches
• Reliability has gone up
• Customer satisfaction has increased
• More time to perform maintenance / inspections

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Study Results

• Start by standardizing transformer fusing
• One simple chart for line crews
• Minimize stock on trucks
• Then select line fusing criteria

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kVA Ratings kVA Ratings   SC Standard Speed (TCC No. 123-6) SC "K Speed (TCC No. 165-6) SC "Fault Tamer (TCC No. 450-8)
Single-Phase Three-Phase FLA Fuse Link (Amperes) Fuse Link (Amperes) Fuse Cartridge(Amperes)
3 9 0.42 1 6K 10
5 15 0.69 2 6K 10
10 30 1.39 3 6K 10
15 45 2.08 5 6K 10
25 75 3.47 7 8K 10
37.5 112.5 5.21 10 10K 10
50 150 6.94 15 12K 10
75 225 10.4 20 20K 20
100 300 13.9 25 25K 20
167 500 23.1 40 40K -
250 750 34.7 65 65K -
333 1000 46.3 80 80K -
conn. ?-?, ?-Y, and Y-Y

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Existing Settings
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Alternate Settings
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Benefits

• Significant reduction in outages
• Smaller areas affected by outages when they do
  occur
• Only 27 of time transformer fuse takes out line
  fuse
• Better fusing schemes
• Customer satisfaction has increased
• Breaker lockouts have been significantly reduced