Which one is the Proper Fault Location Method ? Recommended Fault Location Method Disturbing Voltage Murray Küpfmüller 3-Point (a-b) 3-Point Graaf C unbalance.

Which one is the Proper Fault Location Method ?

Recommended Fault Location Method

Disturbing Voltage▼

Murray▼

Küpfmüller▼

3-Point (a-b)▼

3-Point▼

Graaf▼

C unbalance▼

R difference

Low level

Medium level DC

Medium level AC

High level AC

Intermittent

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Typical Cable FaultsTypical Cable Faults

Insulation Faults

Partly flooded

cable

Totally flooded

cableC b ≠ C a R b ≠ R a

Active Sensitive

Active Sensitive

Active Sensitive

Active Sensitive

ActiveSensitive

ActiveSensitive

Active Protected

Active Protected

Active Protected

Active Protected

ActiveProtected

ActiveProtected

Active Protected

Active Protected

Active Protected

Active Protected

Passive Passive PassivePassive

Active Protected

Active Protected

Passive Passive

PassiveGraafRepeatedKüpfmüller

To learn more click on the selected method!

Passive

Disturbers

The expected disturbing voltage depends on: 

A.) The function of neighboring pairs in the cable  Intermittent disturbing voltages are expected if the neighboring pairs are used for POTS 

DC disturbing voltage is expected if the 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

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Active Bridge Murray Method in Sensitive mode

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  ■ Ф wire a=Ф wire b  ■ FbE>1000 x FaE  ■ FbE>10 MOhm If the disturbing voltages overload the input repeat the measurement in Protected 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

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Active Bridge Murray Method in Protected mode

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  ■ Ф wire a=Ф 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

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

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Passive Bridge Murray Method

The result of Murray measurement is: Lx/LIn addition ECFL 30 provides:  ■ RL loop resistance  ■ FaE insulation resistance  ■ Rx resistance to fault ■ Lx distance to fault

The conditions of accurate results:  ■ Ф wire a=Ф 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

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

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Active Bridge Küpfmüller Method in Sensitive mode

The result of Küpfmüller 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  ■ Ф wire a=Ф 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

Recommended when: ■ booth wires of a pair are faulty■ the level of disturbing voltages are low

The Küpfmüller 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

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Active Bridge Küpfmüller Method in Protected mode

The result of Küpfmüller 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  ■ Ф wire a=Ф 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

Recommended when:■ booth wires of a pair are faulty■ the level of disturbing voltages are medium

The Küpfmüller 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

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Passive Bridge Küpfmüller Method

The result of Küpfmüller measurement is: Lx/LIn 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:  ■ Ф wire a=Ф wire b  ■ 0,5>FaE / FbE>2  ■ FaE + FbE>100 x R loop In case of strongly intermittent disturbing voltages repeat the measurement with the Graaf method

Recommended when:■ booth wires of a pair are faulty■ the level of disturbing voltages are high

The Küpfmüller 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

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The Lx/L results are displayed in two columns and a histogram

Active Bridge Repeated Küpfmüller Method

Recommended when: ■ booth wires of a pair are faulty■ the level of disturbing voltages are intermittent

That method is a sequence of repeated Küpfmüller 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

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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.

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

The result of 3 Point measurement is: Lx/LIn 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

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

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Healthy auxiliary wires

Faulty pair FaE

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

The result of 3 Point measurement is: Lx/LIn 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

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

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Healthy auxiliary wires

Faulty pair FaE

Passive Bridge 3-Point (a-b) Method 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

The result of 3 Point measurement is: Lx/LIn 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 repeat the measurement with the Graaf method

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

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Healthy auxiliary wires

Faulty pair FaE

Active Bridge 3-Point Method in Sensitive mode

The result of 3 Point measurement is: Lx/LIn 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

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

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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 result of 3 Point measurement is: Lx/LIn 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

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

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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 result of 3 Point measurement is: Lx/LIn 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 repeat the measurement with the Graaf method

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

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Synchronous Graaf Method

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 )

Recommended: for Fault Location of Totally Flooded Cables

The level of disturbing DC currents is usually intermittent. For the sake of proper test resultthe 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

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The Theory was perfect: The result doesn't depend on the actual value of currents

The Original Graaf Method and its Problems

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.

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Resistance Difference Measurement

The active bridge of ECFL 30 is accurate and comfortable

The passive bridge of ECFL 30 is disturbing voltage tolerant

ECFL 30 provides the following results: Ra, Rb, Rloop, Δ R, %

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Capacitance Unbalance Measurement

The active bridge of ECFL 30 is accurate and comfortable

The passive bridge of ECFL 30 is disturbing voltage tolerant

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