6.5 DC Fault Location with MURRAY Method
The Murray-method applicable when the two wires of the pair have the
same gauge (
∅), the same length, are made of the same material and
only one of them is leaky. To provide the specified accuracy, the good
wire’s insulation resistance between wire and ground must be at least
1000 times greater then the faulty wire’s insulation resistance between
wire and ground. The insulation resistance of the healthy wire must be
higher than 10 MΩ even if the fault resistance of the faulty wire is smaller
than 10 kΩ. The passive bridge of KMK 8 measures accurately even in
the presence of AC interference voltages on the line.
The measurement can be performed if the healthy and faulty wires are
taken from different pairs. That solution can be applied when all the two
wires of the faulty pair are wet but another healthy pair is available. The
two pairs must be in the same cable
Test Procedure
• Select the DC FAULT LOCATION/MURRAY METHOD
• Press ENTER and then the measuring arrangement appears
.
The far ending of the tested pair should be joined manually or by means
of the remote controllable loop-closing device KLC 8.
• Start the measurement with the START/STOP key
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