IR Hot Spots

IR Hot Spots

Performing IR inspections on transmission lines is primarily conducted from a helicopter. With its ability to reach all points on your system with speed and efficiency, its makes it the preferred platform for inspections. However, many inaccurate results have been obtained because the helicopter platform cannot account for nor control many of the critical factors that affect IR accuracy and reliability.

How accurate and reliable are your aerial IR inspection reports? EPRI research has identified several factors that contribute to accuracy and reliability (Overhead Transmission Inspection and Assessment Guidelines – 2009. EPRI, Palo Alto, CA: 2009. 1017693):

Factors that influence the actual temperature of conductor hardware

  • Emissivity
  • Ambient conditions: Air Temp/Wind/Solar Absorption/Precipitation
  • Circuit Loading

IR Hot Spots

Factors that affect measurement accuracy

  • Emissivity
  • Distance to the object
  • Focus
  • Target size
  • Background
  • Reflection
  • Calibration
  • Spatial resolution
  • Geometry
  • Temperature scale

Convection cooling produced by the wind is the most significant factor in determining conductor or splice temperature. In fact, EPRI research and modeling suggests that wind speeds greater then 5mph begin to impact results and wind speeds grater then 15mph can produce meaningless results. Without knowing the wind speeds at the conductor, circuit loading and air temperature at the time of the picture, can efficient corrective action be recommended based entirely on observed delta temperatures?

IR Hot Spots
Powerline Patrol Services provides ground based IR inspections that control for accuracy and reliability and goes beyond just changes in temperature. We provide the critical elements behind the IR pictures that include ambient conditions at the conductor, distance, viewing angles and any factors we were not able to control for. We believe this approach reduces the false positives and identifies only those components that need corrective action.

The benefits of using Both UV and IR

Many utilities have realized the benefits of IR conductor inspections over the past 10 years and now UV provides the missing element with respect to insulators.

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