Subminiature time delay fuse

Details Subminiature time delay fuse Subminiature time delay fuse

2000-08-25

2002-10-01

Vortman, Anatoly (Department: 2835)

Electricity: electrothermally or thermally actuated switches

Electrothermally actuated switches

Fusible element actuated

C337S187000, C337S228000, C337S229000, C361S626000

Reexamination Certificate

active

06459356

ABSTRACT:

FIELD OF THE INVENTION
This invention relates generally to cable television systems and electronic devices used in such systems, and more specifically fuses included in electronic devices.
BACKGROUND OF THE INVENTION
A communication system
100
, such as a two-way cable television system, is depicted in FIG.
1
. The communication system
100
includes headend equipment
105
for generating forward signals that are transmitted in the forward, or downstream, direction along a communication medium, such as a fiber optic cable
110
, to an optical node
115
that converts optical signals to radio frequency (RF) signals. The RF signals are further transmitted along another communication medium, such as coaxial cable
120
, and are amplified, as necessary, by one or more distribution amplifiers
125
positioned along the communication medium. Taps
130
included in the cable television system split off portions of the forward signals for provision to subscriber equipment
135
, such as set top terminals, computers, and televisions. In a two-way system, the subscriber equipment
135
can also generate reverse signals that are transmitted upstream, amplified by any distribution amplifiers
125
, converted to optical signals, and provided to the headend equipment
105
.
Network powering devices, such as power supplies, are typically included in many of the devices of the communication system
100
or as separate devices located along the communication medium, such as coaxial cable. The power supplies usually generate both 60 volts alternating current (VAC) and 90VAC power and supply 6 amperes (A) to 15A of current to the powered devices, for example, optical nodes or amplifiers. Power supplies are typically located throughout the communication system
100
near the center of a pocket of amplifiers to maximize the power efficiency. AC power from the power supply enters a power inserter installed on the coaxial cable and combines the AC power with the RF signals. The power inserter then directs the power in both directions along the coaxial cable.
One problem that occurs with some regularity in a communication system
100
is a service outage due to powering faults. Typically, a powering fault may be caused by voltage and current surges or lightning strikes that affect the surrounding devices on the coaxial cable. As a result, there is an increased expectation that devices along the communication medium be designed to adequately prevent service outages, or at the least, protect the devices along the communication medium from failure when powering faults occur within the communication system
100
.
Thus, what is needed is a protective device for use in communication devices, such as distribution amplifiers, to provide improved reliability and surge-resistance. Due to development time and the cost of installing new equipment, however, it is also important that a protective device retrofit easily and inexpensively into existing products to keep upgrade costs to a minimum.


REFERENCES:
patent: 4080039 (1978-03-01), Ahroni
patent: 4224592 (1980-09-01), Urani et al.
patent: 4504816 (1985-03-01), Viola et al.
patent: 4544907 (1985-10-01), Takano
patent: 4997393 (1991-03-01), Armando
patent: 5629664 (1997-05-01), Muramatsu et al.
patent: 5682130 (1997-10-01), Styrna et al.
patent: 5854583 (1998-12-01), Falchetti
patent: 56-53 (1981-01-01), None
patent: 57-210537 (1982-12-01), None
patent: 5-205608 (1993-08-01), None
Product Data Sheet for UL/CSA/ANCE (Mexico) 248-14 vx. IEC 127 Fuse, Littlefuse, Inc.

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