Presentation on theme: "IEC IEC Standard defines:"— Presentation transcript:
1IEC 61230 IEC 61230 Standard defines: Test durationTest method and configuration specificPeak current factorTolerancesIEC Standard does not define:Specified current test valuesPass / Fail rated values
2IEC 35kA Rating IEC 61230 35kA Rated values: J configuration test setupRated current – 35kATest duration – 17 CyclesPeak current factor – 2.6AC component of test – 115%Test 115% kA1st cycle peak current – 104.7kA
3IEC 40kA Rating IEC 61230 40kA Rated values: J configuration test setupRated current – 40kATest duration – 17 CyclesPeak current factor – 2.6AC component of test – 115%Test 115% - 46kA1st cycle peak current – 119.6kA
4IEC 55kA Rating IEC 61230 55kA Rated values: J configuration test setupRated current – 55kATest duration – 17 CyclesPeak current factor – 2.6AC component of test – 115%Test 115% - 63kA1st cycle peak current – 164.5kA
5ASTM F855 ASTM F855 Standard defines: Test durationSpecific test current valuesDefined X/R valuesCable test lengthsPass / Fail ratingsASTM F855 Standard does not define:Tolerances
11X/R Ratio Impedance Triangle X/R is a ratio determined by the system reactance “X” divided by the system resistance “R” looking back towards the power source at the time of a fault.X/R determines the DC component of a ground fault and will decay quickly to only AC symmetrical component of fault.Full DC offset occurs at the time when the DC component current is equal to the initial peak value of the AC current.A higher X/R ratio will lead to a longer DC offset where as a small X/R ration will lead to a rapid DC offset.High X/R ratios lead to more severe and damaging ground faults versus small ratios.High X/R ratios are useful for testing purposes to push equipment to its ultimate electrical and mechanical ratings and capabilities.Impedance TriangleApparent Power (kVA)Reactive Power (kVARS)Real Power (kW)
12IEC Ground Fault Testing Resulting waveform of 35kA ground fault test using high X/R ratio with peak current at kA. Full DC offset occurs at the 10th cycle of ground fault.
13IEC Duckbill Testing Duckbill Test Shot Duckbill Slow Motion Test Shot Duckbill Clamp certified to ASTM F855 5H and IEC kA Ratings1st Cycle Peak Current – 104kA, Symmetrical Current 40.3kADuckbill Test ShotDuckbill Slow Motion Test ShotDuckbill Test Shot w/ Ball Stud FailureSlow Motion Failure of Ball StudSolution to failure – 25mm Ball Stud torque rating too low for duckbill application. 30mm Ball Stud torque rating sufficient for use with Duckbill Clamp on ground end.
14IEC 30mm Ball Stud Clamp Testing 30mm Ball Stud Clamp tested to IEC kA Ratings1st Cycle Peak Current – 164kA, Symmetrical Current 63kA30mm Ball Stud Clamp Test Shot30mm Ball Stud Clamp Slow Motion30mm Ball Stud Clamp Heating Failure30mm Ball Stud Clamp Heating Failure Slow MotionSolution to failure – Thread inside of Ball Clamp to to increase surface area at bolt to clamp connection and to reduce arcing at bolt.
15IEC C-Clamp Testing 4” C-Clamp Test Shot 4” C-Clamp tested to IEC kA Ratings1st Cycle Peak Current – 119kA, Symmetrical Current 46kA4” C-Clamp Test Shot4” C-Clamp Slow Motion Test Shot4” C-Clamp Test Shot w/ Ferrule Failure4” C-Clamp Slow Motion Failure of FerruleSolution to failure – Failure was due to high current level and ferrule to clamp connection. Solution to failure is to change to a threaded fitting connecting the ferrule to clamp.
16Safety FirstFun Fact :In just 0.25 seconds, the temperature of the insulating jacket on a ground set reaches 290°F for a 35kA phase to ground fault with a ground set resistance of 1mΩ or less.