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Lightning Arresters and Their Application (System Reliability Enhancement) 2011 SWEDE Conference Steve Brewer Hubbell Power Systems/Ohio Brass SWEDE Conference.

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Presentation on theme: "Lightning Arresters and Their Application (System Reliability Enhancement) 2011 SWEDE Conference Steve Brewer Hubbell Power Systems/Ohio Brass SWEDE Conference."— Presentation transcript:

1 Lightning Arresters and Their Application (System Reliability Enhancement) 2011 SWEDE Conference Steve Brewer Hubbell Power Systems/Ohio Brass SWEDE Conference - April 2011

2 ® Outline Disconnector Reliability Line Insulator Protection Practical/Safety Topics Track Resistant Bracket SWEDE Conference - April 2011

3 ® Disconnector Reliability SWEDE Conference - April 2011

4 Proper Isolator Operation Ground lead separated Normal overcurrent sequence – Protection operates – System re-energized – Voltage holds – Service to end user restored Visual indication of failure SWEDE Conference - April 2011

5 Improper Isolator Operation Ground lead remains intact Normal overcurrent sequence – Protection operates – System re-energized – System trips until lock-out occurs – Service to end user NOT restored No visual indication of failure SWEDE Conference - April 2011

6 ® Resistor Graded Disconnector Time-Current Curve SWEDE Conference - April 2011

7 Capacitor Graded Disconnector Time-Current Curve SWEDE Conference - April 2011

8 ® Line Insulator Protection SWEDE Conference - April 2011

9 ® The Enemy SWEDE Conference - April 2011

10 Traveling Wave/ Overvoltage Protection Lightning hits mid-span Current divides and then propagates V = I x R

11 ® Surge Arresters - Concept Surge causes traveling voltage wave Voltage would be enough to flash-over insulation Surge arrester high resistance at L-G voltage Surge arrester low resistance at surge voltage Surge is diverted to ground Surge arrester high resistance again after surge Conduction time is too short for breakers to react

12 ® Case Histories SWEDE Conference - April 2011

13 ® National Grid Champion International Paper Co. – Operates 363 days/year, 24 hours/day – One interruption costs $50-100k No. 2 line kV, 70 years old – Hired PTI – Installed new OHSW – Improved footing resistances SWEDE Conference - April 2011

14 ® National Grid 115 kV Line without Surge Arresters SWEDE Conference - April 2011

15 ® National Grid 115 kV Line with Surge Arresters SWEDE Conference - April 2011

16 ® Suspended Line Arrester Configuration

17 ® Typical Dead-End Line Arrester Configuration SWEDE Conference - April 2011

18 ® Practical/Safety Topics SWEDE Conference - April 2011

19 ® Practical Issues Must use right rating and type – Too large as bad a too small Lead length affects protection Conductor Size - Min. # 6 AWG – Ground lead must be flexible Reuse of arresters – Not recommended Testing of Arresters – Thermal Imaging holds most promise DOT shipping considerations

20 ® Safety Issues Porcelain arresters – Most dangerous if do not blow up Disconnector operation – Brings line voltage to base of unit

21 ® Track Resistant Bracket SWEDE Conference - April 2011

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