WCA July 2007

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Technology News
49
Wire & Cable ASIA – July/August 2007
By helping cable products meet their
technical specifications, Cropico
precision measurement instrumentation
also ensures that valuable copper raw
material is used efficiently.
The in-line installation of Cropico
D05000 microhmmeters as part of
copper cable production facilities
enables highly accurate low resistance
measurements to be undertaken to
ensure that products meet relevant
technical performance standards and
specifications.
Installation of the D05000 in-line as part
of the production process also eliminates
waste material by cutting off cable
samples and then scrapping the offcuts.
In addition, by constantly monitoring
the resistance value of the cable, the
system also ensures the cost effective
use of copper raw material in the
manufacturing process.
Given the relatively high price of copper,
this factor is a significant consideration
in the cable manufacturing process.
All cable products are designed
and manufactured to close electro-
technical tolerances in keeping with the
requirements of a host of international
product and performance standards.
The cable’s resistance value is
critical in this respect – if resistance
is too high, then the current carrying
capability of the cable is reduced.
Since cable resistance reduces as the
diameter is increased, it is important
that the specified resistance per metre
is achieved in relation to the optimum
diameter of the cable.
Being too generous with the cable
diameter means more copper is being
used than necessary. As copper is
the main contributor to the cost of a
cable, for maximum manufacturing
cost efficiency it is crucial that the
required resistance is achieved with
the minimum cable diameter.
The D05000 uses true four-wire Kelvin
resistance measurement technology to
eliminate lead resistance errors. This
system, alongside auto averaging of
test current and automatic temperature
compensation, ensures the highly
accurate measurement of resistance
in the cable during the manufacturing
process.
In typical manufacturing environments,
the Cropico D05000 is linked to
a specialist clamp which holds a
standard 1 metre length of cable or
wire in place as the copper strands
pass along the bobbin extruder.
The clamp incorporates separate
current and potential measurement
connections, which are attached to the
cable for resistance measurements to
be made.
There are three cable models in
the Cropico range and these offer
the ability to accurately clamp and
measure cable up to 1,000mm2. There
is a model that has an integrated
water bath which will automatically
bring the cable under test to a specific
temperature.
Programmable current levels and
the selection of different test speeds
give the Cropico tester flexibility to
accurately measure the resistance
values of different cable products.
These include single end and plain
soft wires through to bunched,
stranded and large diameter rope type
conductors.
Accurate and reliable in-line cable
resistance measurements taken in
this way enable cable manufacturers
to maintain optimum operating
efficiencies in terms of copper raw
material use.
There are four models in the
D05000 series which form part
of a comprehensive range of
microhmmeters and precision
measurement instrumentation.
Cropico Ltd – UK
Fax : +44 191 586 0227
Email :
Website:
Precision increasing efficiency
Making savings on raw materials ▲