Miyerkules, Oktubre 12

Early Detection System

Thermographic Inspection and Ultrasound Inspection

What is Thermography?

Camera capture and converts the infrared radiation into a state that is visible to us. That is how we can see and measure the heat.

Emissivity or Emittance:

The intensity of the emitted radiation depends on two factors, the temperature of the object and the ability of the object to radiate

What makes Thermography so unique and useful?

Thermography provides us with a powerful tool for non-contact temperature measurement, usually surface temperature measurement. But we also need a basic understanding of how the surface is being heated and what might lie behind that temperature.

Why Thermal Scanning?

  1. Safe to use in high voltage, environmental & mechanical hazards
    • Non-contact measurement
    • Long distance measurement
    • Passive sensing is harmless
    • Thermal pattern is qualitative
    • Temperature measurement is quantitative
    • Non-destructive test (NDT)
  2. Cost saving for energy
    • Energy loss is avoided by early detection of faulty equipments
    • No shutdown required for inspection
  3. Cost saving for maintenance
    • Low repair costs due to early diagnosis of the problems
    • Equipment life is extended by pinpointing faulty components before costly damage

Ultrasound Inspection
  • Hear what can not be seen
  • See what can not be heard
  • Low heard through sound conducting obstacles
  • Detectable in high noise environment 
  • Distance from the power source
  • On line monitoring

Tracking, Arcing or Corona?

  1. Tracking
    • No heat, buzzing sound
    • Starts, gradually builds to crescendo, stops
  2. Arcing
    • Heat and buzzing sound
    • Abrupt start and stop, random
  3. Corona
    • Constant buzzing or sizzling sound
    • No heat detected on low voltage systems
Arcing detected with ultrasound on right hand 13.8 kV switchgear.

Ultrasound Inspection Methods - Outdoor
  • Scan 360 degree area
  • Back and forth
  • Up and down
  • Scan same object from different points
  • Parabolic
  • Use headset or loudspeaker

Ultrasound Inspection Methods - Indoor
  • Back and forth
  • Up and down
  • Scan closed panels 
  • Magnetic flexible wand on panels
  • Switchgear is quiet
  • Above dB micro V (SDT 170) should be investigated
  • Always use headset

Combine Ultrasound and Thermography  for more thorough inspections! 


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