Megger SG32-1500M, Руководство пользователя

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SG32-UG-EN-V01 Dec 2016
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a “dead short” to earth/ground that would be extremely difficult, if not
impossible to pinpoint using acoustic methods.
c. Another effective method of HV Pre-location is the ICE / Impulse
Current method also known as Impulse Surge. This method is effective
for pre-locating high-resistance faults (arc resistance greater than 200
Ω )
where the Arc Reflection method does not work effectively. The Impulse
Current method is similar to the Arc Reflection method in that both
methods send high energy pulses down the cable which are used to break
down the fault. When using the Impulse Current method, a current
coupler is switched into the surge return circuit and is used to measure
the high frequencies transients, seen as a series of spikes each separated
by the time taken for the transients to travel time from the fault back to
the SG32.
It should be noted that the first displayed pulse includes the “ionisation
delay” and should not be used for measurement. In general, the second
or third pulses can be used. Later pulses can distort the measurement as
they have been attenuated by the cable during the multiple reflections.
d. Once the fault has been pre-located by using any of the above methods,
the fault can be pinpointed either by acoustic /electro-magnetic
combination method. Set the SG32 to Impulse Current and set the
discharge voltage to a voltage similar to that used previously. Note: The
lowest possible voltage should be used (as long as it is high enough to
ignite the fault and create a flashover) as this ensures that the maximum
energy is available, making pinpoint location easier. Set the discharge rate
as desired and use the Digiphone Plus Pinpointer to pinpoint the exact
location of the fault.