(1) When it works without fault, Zo＝Zc, P＝0, no reverse.
(2) when the circuit is off line, Zo＝∞, P＝1, it reverse totally and the
polarity of the incoming wave and its reflex are the same.
(3) when the circuit is short circuit, Zo＝1, P＝－1, it minus totally
reverse and the polarity of the incoming wave and its reflex are the
opposite .
When there is an impulse electric wave, the impulse conveys on
the line by the speed of V, and reflex to the input terminal when the
row distance Lxmeets the fault point. The time of the reverse is T,
so the relation is on the below:
V is the speed of the electric wave of the line, and is related to the
linear circuit parameter and constant to an case which can be
detected by the instrument and calculated by computer. When the
displayer show the the impulse and the reverse wave from the fault
point in real time, we can get the time T by providing the
instrument’s time signal. So we can get the location of the fault
point from (2). Different kinds of faults has wave charts as below:
Method of impulse can easily detect the fault in the off line, short
circuit and cable’s low voltage grounding. In the situation of high
resistance fault, for it still shows high resistance in the condition of
low voltage impulse and makes no or few reverse wave. In this
