| |
| The
ARC Stabilisation Unit ARF-1 |
Pulse
echo is the simplest method of fault location, but its use is severely
limited, not being suitable for flashing or high impedance faults.
To overcome these limitation and still use pulse echo techniques
a new method known as arc stabilisation can be used. As the name
suggests the aim is to stabilise an arc at the point of fault, this
arc then being seen and recorded by a suitable pulse echo set. |
Such
an instrument capable of stabilising an arc at the point of fault
is the ARF-1 available from Crotech. The ARF-1 is a compact, easy
to use Arc Stabilisation Unit suitable for use in a modular system
or a cable test van. The ARF-1 is an effective aid to prelocating
the majority of cable faults, quickly, accurately and is suitable
for use by operators of all experiences. |
| Test
Method |
The
energy pulse of a shock discharge generator is applied to the faulty
cable through the arc stabilising unit ARF-1. This pulse ignites
the fault and generates a short-term arc at the fault. Simultaneously,
the ARF-1 triggers the pulse echo set and takes a standard pulse
reflection measurement into what is seen as a short circuit. A typical
configuration is shown in figure 1. The pulse reflected back by
the stabilised arc at the point of fault reaches the pulse echo
set via the high voltage seperating filter "F" and is
stored in the internal memory. This trace is then compared with
a previously recorded trace of the same core, the fault position
is clearly identifiable as the point of divergence between the two
traces. All switching elements necessary for triggering and the
coupling of the pulse, are contained in the ARF-1. After the pre-location
using the arc reflection method, the decoupling elements is bypassed
using a manual switch and the shock discharge generator is ready
for use on its own for acoustic pin-point fault location. |
| Technical
Data |
| Recommended |
SWT-32
1000 Jules. |
| Surge
Generators |
SWT-32D
2000 Jules . |
| ARC
Duration |
>5.0ms
at 8kV
>1.0ms at 32kV. |
| Dimensions
(L x W x H) |
525
x 255 x 490. |
| Weight |
21
Kg.. |
|
|
