Ultrasonic electrical discharge detector

Mechanical and Electrical Applications The range of ultrasonic detectors manufactured by SDT International are hand held, multi-functional instruments which detect, measure, record and analyse naturally occurring airborne and structure borne ultrasound. They also reproduce a faithful representation of the ultrasound in the audible spectrum for listening to, usually through headphones.

Ultrasounds are produced throughout any plant environment due to various forms of friction and act in a very predictable manner. The slightest change in condition is firstly evident in a change in the amount of friction. Valuable information is therefore obtained about the condition of plant and equipment by measuring, monitoring and analysing the ultrasound. Listening to the reproduction of the ultrasound through headphones also provides useful additional information.

Common sources of ultrasound are the friction associated with rolling element bearings, gears, couplings, turbulence in gases and liquids (such as at leaks and valves) and electrical discharges. The SDT ultrasonic detectors are designed for:

• Condition assessment and condition monitoring

• Equipment troubleshooting • Predicting mechanical and electrical faults and failures

• Leak detection and quantification (for energy conservation)

• Tightness (or seal integrity) testing The popular SDT 200 and SDT 270 ultrasonic detectors have built-in airborne ultrasonic sensors and hand-held contact sensors for general maintenance. There is also a wide range of specialised plug-n-play optional accessories available.

Mechanical An SDT ultrasonic detector, other than listening to ultrasound, also measures the ultrasound intensity emitted from a source in dBµV. Ultrasound intensity changes over time in sympathy with condition in rotating equipment such as bearings, gears and couplings. The more friction, the higher the dBµV value, the larger the cause for concern. This “friction” principle is also used for lubrication control.


Partial discharge such as arcing, tracking and corona give off ultrasounds and are all distinguishable. Locate and identify unwanted discharge in MV/HV substations, overhead transmission lines and switchgear, including those within closed panels.


Start typing and press Enter to search