( U/G CABLE FAULT LOCATION SYSTEM)
To achieve high level or economic development extensive electrification is required to meet the growing demand of widely spread industrial manufacturing enterprises and also of increasing domestic consumption. This is made possible by large & wide networks of U/G power cables of diff materials & of diff. voltages.
Although U/G Cable system is considered to be reliable, but due to
various reasons like manufacturing defects, improper transportation & storage of cables, improper installation techniques, various mechanical damages, corrosion damage, abnormal thermal stress, over loading of cable, aging of cables they got damaged.
The Cable fault locating system focuses on localization & pinpointing of cable faults with the required accuracy and within economically justifiable time duration.
Working Principles : All cable fault locating systems are based on pulse reflection. When periodic pulses generated in the system are injected into the Cable Over Test., these are reflected back from those points in cable where there is change in impedance due to irregularities arises due to breaks shorts, and squeezes etc.
COMPACT SYSTEM - Compact System is a U/G Cable fault locating system of Germany make mounted on TATA 407 VAN used for Both HT & LT Cables & up to 160 Km. of length.
For XLPE Cables VLF Unit is provided.
With help of this system identification & route of cable can be found out
This system Consists of Three main Components.
Operation Modes :
- Pin pointing.
Testing : - DC Testing 80 KV.
Voltage 0 to 80 KV. DC.
IN = 15 ma.
Cable up to 66 KV can be tested.
2: Relocation :
- Pulse Echo Method : This method is suitable for prelocating fault distance of open Ckt & short Ckt. Below (40 ohms) fault.
- Impulse Current Method : It is suitable for prelocating low resistive / high resistive. Intermittent fault in a cable. A capacitive discharge is made on faulty core at it’s fault point due to which the surge pulse is reflected from the fault point to testing end and it is carried through a fault location which is connected inductively to the circuitry through impulse current transformer by which the pulse is reflected from fault point to testing end till the capacitive energy is dissipated. The fault echoes can be seen on the CRT Screen of fault locator.
- Surge Voltage Method :Same as impulse current method reuses universal coupling device for higher rating cable.
- Burning (ARM plus Method) : Attempt is made to reduce fault resistance by burning.
3: Pin Pointing :
It is necessary to pin point the exact location of the fault so that the existing cable can be repaired.