Circuit Breaker Failure and Restrike Monitoring
Christopher Hutchinson
Lehigh University, Energy Systems Engineering
ABSTRACT
This project will investigate the
current state of the art measurement
techniques for assessing the restrike
of circuit breakers when used on
utility systems for capacitor bank
switching, focusing on technologies
capable of capturing accurate real
time measurements of the restrike
voltage wave profile and identifying
the triggering event.
INTRODUCTION
Figure 1: Closed circuit breaker
Figure 2: Partially open circuit
breaker with restrike shown
• Restrikes cause poor quality of
power, and are damaging to
equipment.
• Monitoring of restrikes may provide
better quality of power to customers
and longer life to equipment
Picture 1: 500 kV circuit breaker
METHODS (cont)
• Voltage Measurement
• Difficult to measure directly off of capacitor bank
due to extremely high voltage (500 kV).
• Transformation may disrupt transient signal.
• Best course of action is to use PPL’s monitoring
line (220 V). It was determined that transience
would still be visible.
• Additional possible method is using an electric
field sensor to detect transient voltages. This
method is currently being investigated.
• Current Measurement
• Current is constant
throughout capacitor
bank, so measurement
may be take at any point
on the structure.
• Best course is to use a
current transformer
installed on the grounding
wire of phase A.
Picture 2: Capacitor bank structure
CONCLUSIONS AND
FUTURE WORK
• This project is currently ongoing.
• A reliable system using a current
transformer and a transimpedance
amplifier has been designed.
•  Voltage measuring will be
accomplished using PPL’s monitoring
line.
• A data acquisition device within
budget has been identified.
Picture 3: Current
measurement location
• Data Acquisition
• Suggested minimum sampling rate of 64 samples/
cycle (3,840 samples/sec).
• Data acquisition unit will work with a laptop
computer housed in the building with the voltage
monitoring line.
• Satisfactory laboratory testing will
result in system being installed at the
Albretis substation, followed by the
Juniata substation.
• Ideal results will show clear transient
voltages (Figure 3) and currents
(Figure 4) indicative of a restrike.
• This system could then be used at
other substations to monitor the
occurrence and frequency of restrikes.
METHODS
ACKNOWLEDGEMENTS
• Voltage and current measurement
techniques were identified and
tested in a small scale laboratory
setting.
• Data measurement system installed
at Albertis substation for full scale
test.
• System installed at Juniata
substation for measurement.
Figure 3: Restrike voltage
wave profile
Figure 4: Restrike current
wave profile
I would to thank Dr. Richard Decker
(Lehigh University) for working
diligently on this project with me. David
Soyster (PPL) has been an invaluable
resource as well. I would also like to
thank PPL engineers Nick Zeyman,
David Neff, and Jeff Gilbert.