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

2. SWEDE Conference - April 2011
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. SWEDE Conference - April 2011
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. SWEDE Conference - April 2011
Case Histories
SWEDE Conference - April 2011

13. SWEDE Conference - April 2011
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 10

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 Too large as bad a too small
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 Disconnector operation
Most dangerous if do not blow up
Disconnector operation
Brings line voltage to base of unit

21. Track Resistant Bracket
SWEDE Conference - April 2011