DFA100 for Gas Insulated Substations


The DFA100, Dielectric Fault Analyzer, is our new handheld instrument for acoustic diagnosis of GIS. It is a battery-powered instrument for detection and location of defects in the insulation of GIS systems. The DFA100 includes an acoustic emission (AE) sensor to detect acoustic signals from a range of defects such as bouncing particles, protrusions and mechanical loose parts. DFA100 is a further development of its predecessor AIA, a widely known and accepted tool for diagnosis of GIS. 



  • Non-intrusive in-service test of GIS
  • Detection, location, and identification of PD, particles, protrusions and mechanical defects
  • Reliable condition assessment of GIS


  • Portable and handheld tool for inspection and monitoring of GIS
  • Condition based monitoring of GIS during commissioning and in-service
  • Design and factory testing during manufacturing
  • The DFA100 can be directly applied to any earthed component that is associated with apparatus under test


  • Rapid results – the DFA100 is quick and easy to configure, giving results in seconds
  • Reliability and ease of use – the DFA100 produces high quality results with high repeatability, allowing rapid and reliable decision-making
  • Battery operated – the DFA100 is a stand-alone handheld instrument, which can operate up to 4 hours on one charge
  • Wireless synchronization – the DFA100 is utilizing a wireless synchronization module for timing PD and mechanical activity against the power system frequency
  • Selectable settings – the DFA100 provides recommended settings for testing both SF6 filled and oil filled equipment 
  • Rugged and reliable – the DFA100 is an instrument with outstanding durability for field use
  • Simple, user-friendly PC interface – a simple interface allows the test results to be uploaded to a PC. Previous data and nameplate configurations can also be downloaded to the DFA100


DFA100 offers three measuring modes: continuous, phase, and pulse

Continuous mode:

The continuous mode is used for surveying the apparatus and locating the primary source of the acoustic emission (AE) signal. The continuous measuring mode provides four scales of acoustic signal measurement: the RMS signal, peak signal, degree of modulation with fundamental frequency, and degree of modulation with second harmonic frequency.

Phase mode:

The phase mode correlates the acoustic signal and the fundamental power signal, and generates an amplitude vs. phase plot. This information is used to determine the synchronizing nature of the acoustical discharges relative to the fundamental power signal. The patterns obtained are used to identify the nature of the source: PD, particles, and mechanical defects.

Pulse mode:

The pulse mode is primarily used for monitoring particles. The Pulse Mode plots the amplitude vs. time between hits.

Additional Applications

The DFA100 can optionally be equipped with insulated wave guides to detect internal PD on live equipment up to 145 KV.

Information sheets: