ULD-406 – Contact

The contact probe is an accessory of the ULD-40, our Ultrasonic Corona/Arcing Detector. The magnetic probe detects internal discharges caused by insulation breakdown in transformers, capacitors and switchgears.

The ULD-40

The ULD-40 is an ultrasonic detector designed for corona and arcing inspections for predictive maintenance in electric utilities. Corona effect occurs when electricity is discharges into the surrounding atmosphere form a high voltage source. Corona effects and electrical arcs in the air emit ultrasounds. The role of the ULD-40 consists of capturing emitted ultrasounds and of translating them into the audible range. This equipment is perfect for high voltage maintenance program.

Application of the contact probe

The magnetic probe detects internal partial discharges in:

  • Transformers
  • Capacitors
  • Switchgears
  • And more

The sound is propagated by longitudinal waves through virtually any mediums including metal, oil, air etc. Internal high voltage components noise will be heard with the ULD-406.


The contact probe provides and immediate and accurate indication of the presence of internal discharge activity. The magnetic sensor allows users to pinpoint the problem without interruption of service of the high voltage equipment. The probe is very easy to use and gives an excellent contact surface. Early detection of partial discharges in transformers, capacitors or switchgears prevents catastrophic failures.


  • Quick and easy detection of internal partial discharges in transformers, capacitors and switchgears to prevent failures.
  • Is not necessary to shutdown and de-energized the equipment under test
  • Magnetic sensor
  • Pinpoint the problem
  • Large contact surface, small to ease access to the equipment under test


ULD-406 English