Which one is the Proper Fault Location Method ?
Typical Cable Faults Insulation Faults Partly flooded cable Totally flooded C b C a R b R a Recommended Fault Location Method Disturbing Voltage Murray Kpfmller 3-Point (a-b) 3-Point Graaf C unbalance R difference Low level Medium levelDC Medium levelAC High levelAC Intermittent Active Sensitive Active Sensitive Active Sensitive Active Sensitive Active Sensitive Active Sensitive Active Protected Active Protected Active Protected Active Protected Active Protected Active Protected Active Protected Active Protected Active Protected Active Protected Active Protected Active Protected Passive Passive Passive Passive Passive Passive Repeated Kpfmller Graaf Passive Passive To learn more click on the selected method! ELEKTRNIKA Disturbers ELEKTR NIKA The expected disturbing voltage depends on:
A.) The function of neighboring pairs in thecable Intermittent disturbing voltages are expected if the neighboring pairs are used for POTS DC disturbing voltage is expected ifthe neighboring pairs are used only for ISDN No disturbing voltage is expected if the neighboring pairs are used only for data transfer B.) The distance to electrical railway High disturbing AC voltage is expected if the cable is very close to the track Low disturbing AC voltage is expected if the cable is fare enough from the track ELEKTRNIKA Active Bridge Murray Method in Sensitive mode
Recommended when: only one wire of a pair is faulty the level of disturbing voltages are low The Murray method consists of 2 measurements: Measurement of disturbing voltages Bridge measurement with strap on the far end ECFL 30 automatically performs the 2 measurements with the help of the remote controlled switch ELC 30 The result of Murray measurement is: Lx/L In addition ECFL 30 provides: RL loop resistance FaE insulation resistance Rx resistance to fault Lx distance to fault The conditions of accurate results: Ia and Ib < 450 uA wire a= wire b FbE>1000 x FaE FbE>10 MOhm If the disturbing voltages overload the input repeat the measurement in Protected mode ELEKTRNIKA Active Bridge Murray Method in Protected mode
Recommended when: only one wire of a pair is faulty the level of disturbing voltages are medium The Murray method consists of 2 measurements: Measurement of disturbing voltages Bridge measurement with strap on the far end ECFL 30 automatically performs the 2 measurements with the help of the remote controlled switch ELC 30 The result of Murray measurement is: Lx/L In addition ECFL 30 provides: RL loop resistance FaE insulation resistance Rx resistance to fault Lx distance to fault The conditions of accurate results: Ia and Ib < 7 mA wire a= wire b FbE>1000 x FaE FbE>10 MOhm If the disturbing voltages overload the input repeat the measurement with the passive bridge of ECFL 30 ELEKTRNIKA Passive Bridge Murray Method
Recommended when: only one wire of a pair is faulty the level of disturbing voltages are high The Murray method requires manual bridge balancing with helipot M. the measuring voltage is connected to the ground wire a and wire b should be interconnected at the far end The far end can be automatically closed/open with the help of the remote controlled switch ELC 30 The result of Murray measurement is: Lx/L In addition ECFL 30 provides: RL loop resistance FaE insulation resistance Rx resistance to fault Lx distance to fault The conditions of accurate results: wire a= wire b FbE>1000 x FaE FbE>10 MOhm If the disturbing voltages overload the input repeat the measurement with the passive bridge of ECFL 30 ELEKTRNIKA Active Bridge Kpfmller Method in Sensitive mode
Recommended when: booth wires of a pair are faulty the level of disturbing voltages are low The Kpfmller method consists of 2 measurements: First measurement with open far end Second measurement with strap on the far end ECFL 30 automatically performs the 2 measurements with the help of the remote controlled switch ELC 30 The result of Kpfmller measurement is: Lx/L In addition ECFL 30 provides: RL loop resistance FaE and FbE insulation resistances Rx resistance to fault Lx distance to fault The conditions of accurate results: Ia and Ib < 450 uA wire a= wire b 0,5>FaE / FbE>2 FaE + FbE>100 x R loop If the disturbing voltages overload the input repeat the measurement in Protected mode ELEKTRNIKA Active Bridge Kpfmller Method in Protected mode
Recommended when: booth wires of a pair are faulty the level of disturbing voltages are medium The Kpfmller method consists of 2 measurements: First measurement with open far end Second measurement with strap on the far end ECFL 30 automatically performs the 2 measurements with the help of the remote controlled switch ELC 30 The result of Kpfmller measurement is: Lx/L In addition ECFL 30 provides: RL loop resistance FaE and FbE insulation resistances Rx resistance to fault Lx distance to fault The conditions of accurate results: Ia and Ib < 7 mA wire a= wire b 0,5>FaE / FbE>2 FaE + FbE>100 x R loop If the disturbing voltages overload the input repeat the measurement with the passive bridge of ECFL 30 ELEKTRNIKA Passive Bridge Kpfmller Method
Recommended when: booth wires of a pair are faulty the level of disturbing voltages are high The Kpfmller method requires 2 manual bridge balancings with helipot M. First balancing with open far end Second balancing with strap on the far end The far end can be automatically closed/open with the help of the remote controlled switch ELC 30 The result of Kpfmller measurement is: Lx/L In addition ECFL 30 provides: RL loop resistance FaE and FbE insulation resistances Rx resistance to fault Lx distance to fault The conditions of accurate results: wire a= wire b 0,5>FaE / FbE>2 FaE + FbE>100 x R loop In case of strongly intermittent disturbing voltages repeatthe measurement with the Graaf method ELEKTRNIKA Active Bridge Repeated Kpfmller Method
Recommended when: booth wires of a pair are faulty the level of disturbing voltages are intermittent That method is a sequence of repeated Kpfmller measurements consisting of 15 part measurements alternating : 8 measurements with open loop (L) 7 measurements with closed loop (K) The far end is automatically closed/open with the help of the remote controlled switch ELC 30 The Lx/L results are displayed in two columns and a histogram When the sequence is completed ECFL 30 selects the acceptable Lx/L results and calculates the average of the accepted results.The unacceptable results are omitted and marked with asterisks. ELEKTRNIKA Active Bridge 3-Point (a-b) Method in Sensitive mode
Recommended when: the insulation between wires and ground is good the insulation resistance between wires a and b is low some healthy pairs are available the level of disturbing voltages are low Faulty pair FaE Healthy auxiliary wires The 3-Point method consists of 3 measurements: First measurement when the measuring voltage is connected to wire a Second measurement when the measuring voltage is connected to the ground Third measurement when the measuring voltage is connected to wire c ECFL 30 automatically performs the 3 measurements with the help of the remote controlled switch ELC 30 The result of 3 Point measurement is: Lx/L In addition ECFL 30 provides: RL loop resistance FaE insulation resistance Rx resistance to fault Lx distance to fault The conditions of accurate results: Ia and Ib < 450 uA The insulation resistance of auxiliary wires must be thousand time as high than that of the faulty one. If the disturbing voltages overload the input repeat the measurement in Protected mode ELEKTRNIKA Active Bridge 3-Point (a-b) Method in Protected mode
Recommended when: the insulation between wires and ground is good the insulation resistance between wires a and b is low some healthy pairs are available the level of disturbing voltages are medium Faulty pair FaE Healthy auxiliary wires The 3-Point method consists of 3 measurements: First measurement when the measuring voltage is connected to wire a Second measurement when the measuring voltage is connected to the ground Third measurement when the measuring voltage is connected to wire c ECFL 30 automatically performs the 3 measurements with the help of the remote controlled switch ELC 30 The result of 3 Point measurement is: Lx/L In addition ECFL 30 provides: RL loop resistance FaE insulation resistance Rx resistance to fault Lx distance to fault The conditions of accurate results: Ia and Ib < 7mA The insulation resistance of auxiliary wires must be thousand time as high than that of the faulty one. If the disturbing voltage overload the input repeat the measurement with the passive bridge of ECFL 30 ELEKTRNIKA Passive Bridge 3-Point (a-b) Method
Recommended when: the insulation between wires and ground is good the insulation resistance between wires a and b is low some healthy pairs are available the level of disturbing voltages are high Faulty pair FaE Healthy auxiliary wires The 3-Point method requires 3 manual bridge balancing with helipot M. First balancing when the measuring voltage is connected to wire a Second balancing when the measuring voltage is connected to the ground Third balancing when the measuring voltage is connected to wire c The far end can be automatically closed with the help of the remote controlled switch ELC 30 The result of 3 Point measurement is: Lx/L In addition ECFL 30 provides: RL loop resistance FaE insulation resistance Rx resistance to fault Lx distance to fault The condition of accurate results: The insulation resistance of auxiliary wires must be thousand time as high than that of the faulty one. In case of strongly intermittent disturbing voltages repeatthe measurement with the Graaf method ELEKTRNIKA Active Bridge 3-Point Method in Sensitive mode
Recommended when: the gauge of wires in a pair are different some healthy pairs are available the level of disturbing voltages are low The 3-Point method consists of 3 measurements: First measurement when the measuring voltage is connected to wire a Second measurement when the measuring voltage is connected to the ground Third measurement when the measuring voltage is connected to wire c ECFL 30 automatically performs the 3 measurements with the help of the remote controlled switch ELC 30 The result of 3 Point measurement is: Lx/L In addition ECFL 30 provides: RL loop resistance FaE insulation resistance Rx resistance to fault Lx distance to fault The conditions of accurate results: Ia and Ib < 450 uA The insulation resistance of auxiliary wires must be thousand time as high than that of the faulty one. If the disturbing voltages overload the input repeat the measurement in Protected mode ELEKTRNIKA Active Bridge 3-Point Method in Protected mode
Recommended when: the gauge of wires in a pair are different some healthy pairs are available the level of disturbing voltages are medium The 3-Point method consists of 3 measurements: First measurement when the measuring voltage is connected to wire a Second measurement when the measuring voltage is connected to the ground Third measurement when the measuring voltage is connected to wire c ECFL 30 automatically performs the 3 measurements with the help of the remote controlled switch ELC 30 The result of 3 Point measurement is: Lx/L In addition ECFL 30 provides: RL loop resistance FaE insulation resistance Rx resistance to fault Lx distance to fault The conditions of accurate results: Ia and Ib < 7mA The insulation resistance of auxiliary wires must be thousand time as high than that of the faulty one. If the disturbing voltage overload the input repeat the measurement with the passive bridge of ECFL 30 ELEKTRNIKA Passive Bridge 3-Point Method
Recommended when: the gauge of wires in a pair are different some healthy pairs are available the level of disturbing voltages are high The 3-Point method requires 3 manual bridge balancings with helipot M. First balancing when the measuring voltage is connected to wire a Second balancing when the measuring voltage is connected to the ground Third balancing when the measuring voltage is connected to wire c The far end can be automatically closed with the help of the remote controlled switch ELC 30 The result of 3 Point measurement is: Lx/L In addition ECFL 30 provides: RL loop resistance FaE insulation resistance Rx resistance to fault Lx distance to fault The condition of accurate results: The insulation resistance of auxiliary wires must be thousand time as high than that of the faulty one. In case of strongly intermittent disturbing voltages repeatthe measurement with the Graaf method ELEKTRNIKA Synchronous Graaf Method
Recommended: for Fault Location of Totally Flooded Cables Graaf method can be used when no other method is applicable due to disturbing DC currents. That method is based on disturbing DC current measurement at the ends of the tested pair. The location of fault is calculated from the rate of the measured DC currents(I1 / I2 ) The level of disturbing DC currents is usually intermittent. For the sake of proper test result the master and slave instruments perform synchronous current measurements at the cable ends. In this case the current rate ( I1 / I2 ) does not depend on the actual value of disturbing currents. Notice: The current measuring method was invented by Dr Robert Van de Graaf in 1931 ELEKTRNIKA The Original Graaf Method and its Problems
The Theory was perfect: The result doesn't depend on the actual value of currents But in the practice it was not satisfactory due to the following problems: 1.)The sensitivity and accuracy of available current meters were not enough at that time 2.)The reading of meters was strongly subjective in case of intermitting currents ECFL 30 eliminates all the problems of the original Graaf method: 1.) The features of current meters are much better (Sensitivity:3 uA,Ri:1 Ohm,Accuracy: 0,3%) 2.) The master and slave instruments perform synchronous current measurements at the cable ends. ELEKTRNIKA Resistance Difference Measurement
Theactive bridge of ECFL 30 is accurate and comfortable Thepassive bridge of ECFL 30 is disturbing voltage tolerant ECFL 30 provides the following results: Ra, Rb, Rloop, R, % ELEKTRNIKA Capacitance Unbalance Measurement
Theactive bridge of ECFL 30 is accurate and comfortable Thepassive bridge of ECFL 30 is disturbing voltage tolerant ELEKTRNIKA THANK YOU FOR YOUR ATTENTION!