EoW November 2010

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EuroWire – November 2010 45
Compounds & colourings
Durable, flexible
semicon jacketing
Dow Endurance™ DHDA-7708 BK is
appropriate for medium, high and
extra-high voltage (MV, HV, EHV)
applications and can be applied as a
thin layer over an existing jacketing
grade during manufacture or as a
cable jacket extruded entirely of this
semiconducting compound.
The compound provides a reliable
earth (ground) continuity path to allow
integrity testing of the cable jacket
upon installation or years later. The
material can be used in any situation
where graphite has traditionally been
used, but is a particularly good choice
where cables are installed in air, for
example, in duct systems or tunnels
– or where ground conditions make
testing graphite-coated cables difficult.
Unlike graphite, Dow Endurance
DHDA-7708 BK resists being washed
and abraded from the surface of the
cable during installation and over years
of service.
When used as the sole jacketing
material, Dow Endurance DHDA-7708
BK provides continuous earthing
(grounding) along the entire cable.
This affords additional protection from
surges and transients, such as lightning.
The compound can be used for both
land and subsea cables.
In addition to delivering the important
conductive properties for monitoring
and electrical functionalities, Dow
Endurance DHDA-7708 BK also delivers
excellent protective characteristics
required for jacketing over MV, HV and
EHV power cables.
It provides the mechanical strength
and durability of a normal insulating
jacket.
Compared to conventional thermo-
plastic semiconductive materials, this
compound is said to offer improved
environmental stress-crack resistance,
better thermomechanical and low-
temperature properties (flexibility in
colder climates), easier strippability
and stronger cut-through and abrasion
resistance.
The compound also offers reduced
moisture vapour transmission and
adhesion to strippable insulation shield
– all while reducing system cost at the
time of installation and over the life of
the cable.
DowWire & Cable – Switzerland
Website:
Doubling the throughput of
additive feeders
An advanced model of the Maguire® MGF gravimetric feeder is said to provide more
than double the throughput of the original system, but has the same compact size.
Used for feeding colourants and additives into plastics processing machines, the new
MGF system is driven by a motor that is smaller than that in the earlier feeder but
delivers material at rates of up to 36kg (80lb) per hour, compared with the previous top
throughput of 13.6kg (30lb).
Also new is a networking option; controllers for the MGF feeders can now be net-
worked with Maguire’s Gravimetric Gateway™ or G2™ software. This program provides
exhaustive material-usage reports, displays alarms from anywhere in the network, gives
access to specific machines from remote locations and monitors inventory levels.
“The increased throughput of the MGF feeder increases the applicability of this system
without any compromise in compactness and affordability,” said Paul Edmondson,
general manager of Maguire Europe. “At the same time, this advanced system
enables more companies to obtain the advantages of gravimetric feeders over the
volumetric devices that currently dominate the industry. Gravimetric feeders are less
complicated, easier to use and more accurate.”
The accuracy of the MGF feeder stems from the use of load cells to monitor the loss in
weight of colourant in a hopper (mounted on the load cell) as the material is fed into
the processing machine by an auger.
Software in the feeder control scans data on colour consumption every half-second and
automatically adjusts dispensing when a predetermined amount of accumulated error
is detected.
“By responding exclusively to accumulated error over a given period of time, Maguire’s
proprietary software focuses on real changes in throughput, not transitory or
anomalous changes caused by vibration, clumping, or surges,” Mr Edmondson said.
“Thus the system provides real-time control and smooth metering consistency.”
Maguire Products Inc – USA
Website:
High-throughput MGF gravimetric feeder ▲