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7.2WFNHO80

Description
specialty fuses 72kv80a3"motorstart
CategoryCircuit protection   
File Size2MB,65 Pages
ManufacturerBussmann (Eaton)
Download Datasheet Parametric View All

7.2WFNHO80 Overview

specialty fuses 72kv80a3"motorstart

7.2WFNHO80 Parametric

Parameter NameAttribute value
ManufactureCooper Bussm
Product CategorySpecialty Fuses
RoHSN
Current Rating80 A
Voltage Rating AC7.2 kV
Mounting StyleStud
Termination StyleBolt Dow
Indicator StyleStriker Pi
PackagingBulk
ProducMedium Voltage Fuses
Factory Pack Quantity1
TypeMotor Fuse Links DIN
Unit Weigh453.592 mg
High Voltage Fuse Technology
For the protection of equipment operating above 1000 volts AC
Current Limiting
Current limiting HV fuse links split into three
internationally recognised types:
back-up
(or
partial
range)
fuse links, which will interrupt any current
from their rated breaking capacity down to a minimum
breaking current specified by the manufacturer; and
general purpose
fuse links, which will interrupt all
currents from rated breaking capacity down to a
current that will melt the elements within one hour.
A third type is the full range fuse. This term applies
to fuse links that can interrupt any current below
the rated breaking capacity that melts the fuse
elements satisfactorily.
Current limiting
back-up fuse links
are the closest in
construction to LV cartridge types. However, a longer strip
element with many more restrictions is necessary to
produce the large number of series arcs needed to
interrupt a high voltage. Fuse manufacturers achieve
this by coiling the element around a ceramic core with a
star shaped cross section. In this way, a 1m long element
can be fitted into a 250mm long fuse body. If the adjacent
coils are too close, there will be a flashover between
them and this sets a practical limit on how long an
element can be crammed into a particular cartridge, and
how many elements can be used in parallel.
Cross Section
End cap
Porcelain barrel
Star core
Moisture tight seal
Star core
Silver ceramic
point contact
Striker coil
Granular
Quartz
Fuse elements
Porcelain barrel
Fuse elements
Granular Quartz
Striker coil
Expelled striker
Like an LV cartridge fuse link, an HV fuse link of this
type has a ceramic body.
Many HV current limiting fuse links are also fitted with
a
striker mechanism.
This not only provides the user
with a visual indication that the fuse link has operated,
but can also be used to operate other switchgear. In
this way, a fuse on a single phase system can cut off all
three phases if a fault occurs.
Striker mechanisms are driven by explosive charges or
compressed springs. Both are triggered by a thin fuse
wire running the length of the fuse, usually through the
centre of the star shaped core. The wire is connected
in parallel with the elements, so a current flows
through it when the elements melt. The current
heats up the wire and detonates the explosive
charge, or melts the wire andreleases the spring,
pushing the striker pin out of the fuse link’s end
cap. A lock washer mechanism makes it impossible
to push the pin back into the fuse body.
There are several variations on this design for specific
applications. For example, the elements in three-
phase motor protection fuse links are corrugated to
withstand the cyclical mechanical stresses induced
by the high starting and stopping currents drawn
by the motor.
1
For
more information visit our website
www.bussmann.com

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