Cable fault locators are used for diagnostics of power cable lines, identification of their damage sites, requiring serious instrumentation. One of the most important problems of diagnostics of engineering utilities is location of cable line and pinpointing of damaged spot. As a result, these locate the exact place of damage.
CABLE FAULT LOCATION
A table below can help you select the right model of cable fault locator.
Types of cable damage diagnosed by cable fault locators equipment:
– single-phase to ground short circuit;
– phase fault;
– two-, three-phase ground short circuit;
– cable breakage without grounding or with grounding;
– both dangling and unbroken veins;
– intermittent breakdown, manifested in the form of short-circuit (breakdown)
at high voltage and disappearing
(floating) at rated voltage.
Main methods of pinpointing damage spot:
1. Loop method;
2. Method of invoice frame;
3. The method of oscillatory discharge;
4. Capacitive method;
5. Pulse method;
6. Induction method;
7. Acoustic method.
Induction method of fault location
This method is used to directly locate damage on the cable route when breakdown of the insulation lived among themselves or to the “ground”, a cliff with simultaneous breakdown of isolation between veins or to the “ground” to determine the cable route and its depth, to determine the location coupling positions.
The essence of the method consists
The method is based on detection of electromagnetic field changes with EM sensor. The electromagnetic signal is passing through the utility at certain frequency (512 Hz, 33 kHz) at current up to 10A. EM signal level depends on utility’s current distribution quality and position of locator sensor in relation to the cable.
Cable fault location equipment – Knowing the nature of the field change, and having enough experience, it is possible to determine the path of the cable laying and detect up to one hundred types of cable damage just by changing frame orientation. More precise results are obtained when electric current passes through the “strand” circuit, which was burnt down to «single-phase short circuits to two or three-phase in order to create artificial “cable sheath” chain, grounding the latter from both sides.