Megger TDS40, Руководство по эксплуатации, Страница: 35 / 71

4-35
4.2 Sheath Fault Location
Following a failed sheath test with DC voltage fault location based on the step voltage
method can be immediately performed at the cable under test with the test and diagnosis
system serving as voltage source.
The test current coming from the pulsed DC source is flowing into the ground at the point
of fault and results in a maximum step voltage at the fault. This peak is located with an
earth fault locator (e.g. ESG).
By turning the knob / push-button (Fig. 3, item 6) the
SFL operation mode has to be
selected. Afterwards, the voltage level (max. 10 kV) and the pulse rate can be selected as
described in the section before.
By changing the pulse rate you can vary the cycle period too (between 4 or 6 seconds).
E.g. the setting 4s 1:3 enables 4 seconds cycles where 1 second of high voltage is
followed by a 3 seconds dropout.
Fig. 15: Selection of the pulse rate
SFL mode
10kV
*4s 1:3
Set pulsing . OK?