On Load Tap Changer Analyzer – TAP4

Ref : TAP-4

The TAP-4 is the first instrument to use vibro-acoustic measurement to perform tests on On-Load Tap Changers (OLTC).

Thanks to its innovative method based on recording and analysis of vibro-acoustic signals, the TAP-4, like a stethoscope will perform a complete check-up of the internal mechanical state of the OLTC without opening it!
It is able to detect a great variety of mechanical malfunctions : contact wear, arcing in diverter, arcing in selector, synchronism problem, drive mechanism problem, brake failure etc.

The TAP-4 is a universal device, it adapts itself to any type of transformers: MR Reinhausen, ABB, Ferranti, Federal Pioneer and others.

The instrument is used with a current sensor clamp and 1 to 3 accelerometers, therefore you can personalize it according to your needs. Also, its technology has been approved by Hydro-Québec and recognized by international associations such as IEEE and the Cigré.

We also pay strong attention to the high quality of our products so that they can resist impacts and extreme conditions (-20°C to 70°C) with a life expectancy that exceeds 15 proved years.

OpenZen TAP Software

The Tap-4 is driven with a powerful and user-friendly software, OpenZen-TAP, to record and analyze the OLTC events.

The software integrates many calculation and graphic functions to be able to build tests references and tests recordings for comparison analysis.


  • Database with over 70 OLTC models
  • Spots out malfunctions only detectable with a high sampling vibration (100KHz)
  • Can be used on any type of transformers
  • Efficiency in testing due to On-Line/Off-Line operation and non-intrusive methods
  • 2 years guarantee
  • Resolution: 16 bits conversion (+/-LSB)
  • Voltage range: +/- 10 V
  • Frequency range: DC to 300 kHz
  • Signal to noise ratio: Better than 80 dB
  • Sampling time: 10 μs
  • Sampling frequency: 100 kHz
  • Recording time: Unlimited