EA Technology
UltraTEV Monitor
TM
Operating Manual
2178L014
7
2
Introduction
2.1
General
Partial discharges are electric discharges that do not completely bridge the electrodes. The
magnitude of such discharges is usually small; however they do cause progressive deterioration of
insulation that may lead to eventual failure.
Non-intrusive partial discharge detection provides a means for identifying these potential sources
of insulation failure that result not only in loss of supply to customers, but can also endanger staff.
A partial discharge emits energy in the following ways:
Electromagnetic:
Radio
Light
Heat
Acoustic:
Audio
Ultrasonic
Gases:
Ozone
Nitrous oxides
The most practical techniques for non-intrusive testing are based on the detection of the radio
frequency part of the electromagnetic spectrum and ultrasonic emissions. The UltraTEV Monitor has
been specifically developed to enable electromagnetic and ultrasonic activity to be monitored in a
single simple to use instrument.
2.2
Airborne Ultrasonic Discharge Activity
Acoustic emissions from partial discharge activity are normally at a frequency too high for the human
ear, i.e. ultrasonic. As the partial discharge progresses towards failure the frequency sometimes
decreases into the audible range.
Using an instrument to detect the ultrasonic signal has several advantages: instruments are more
sensitive than the human ear, are not operator dependent and ultrasonic frequencies are more
directional. The most sensitive method of detection is using an airborne ultrasonic microphone. This
method is very successful at detecting partial discharge activity provided there is an air path between
the source and the microphone. However, in the case of sealed switchgear with no air path, an
ultrasonic contact probe can be magnetically attached to the external surface of the switchgear to
monitor internal activity.
2.3
Electromagnetic Discharge Activity
When partial discharge activity occurs within high voltage switchgear it generates Transient Earth
Voltages (TEV) and electromagnetic waves in the radio frequency range.
Summary of Contents for UltraTEV Monitor
Page 1: ......
Page 2: ......
Page 3: ...UltraTEV Monitor Operating Manual Product Code UTM2 Version 4 October 2016...
Page 4: ...EA Technology UltraTEV MonitorTM Operating Manual 2178L014 1...
Page 78: ...EA Technology UltraTEV MonitorTM Operating Manual 2178L014 75...
Page 95: ...EA Technology UltraTEV MonitorTM Operating Manual 2178L014 92 27 Notes...
Page 112: ......