Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electrical power distribution systems and devices
Reexamination Certificate
1998-12-30
2002-12-17
Barrera, Ramon M. (Department: 2832)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electrical power distribution systems and devices
C361S624000, C361S725000, C361S730000, C361S787000, C361S791000, C361S799000
Reexamination Certificate
active
06496358
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a breaker apparatus and breaker unit suitably applicable to a power distributing apparatus for use in communication systems.
(2) Description of the Related Art
In a terminal station of a communication system, a breaker apparatus is provided in a power distributing apparatus which is for the purpose of distributing power, fed through a power-supply line, to each of units in that station. The breaker apparatus is made up of a breaker (NFB: Non Fuse Breaker) which serves as a current limiter for, when a current exceeding a predetermined value flows, breaking that current, with a current supplied being made to be fed through the NFB to each of the units so that the supply of an excessive current exceeding an allowable value of each of the units thereto is preventable.
Meanwhile, for coping with a system extension in the future, a communication system is usually designed in consideration of the enlargement of an exchange system associated with the extension of that communication system. Accordingly, in a power distributing apparatus including such a prior breaker apparatus, the power-supply ability per one rack column is determined on the basis of the maximum number of racks or units in the station, and the power distributing apparatus is designed and manufactured to exhibit the maximum power-supply ability.
In addition, the communication system is requested to execute the maintenance without its stopping, and therefore, employs a double-powered construction.
There are a CG (Communication Ground) forming a return ground for a power supply, a SG (Signal Ground) being a ground for a signal, and an FG (Frame Ground) for human-body protection among the kinds of grounding for a communication system,. Further, the ground systems are classified into an isolated ground system and an integrated ground system, and in the case of communication systems installed overseas, either the isolated ground system or the integrated ground system is taken according to the standard the nation concerned employs.
The isolated ground system is principally employed in Japan, European nations and other countries, and in this system, all the ground earths are gathered at a GW (Ground Window) in a station house and then connected to a main ground at one point (see FIG.
3
). Thus, since the isolated ground system takes a structure in which the FGs are connected at one point, an advantage exists in that, even if that building is struck by thunderbolt or the like, it is difficult that the noises caused by the thunderbolt or the like are introduced through the FGs into the system, whereas there is a disadvantage in that the ground lines are led from the communication system to a power room of each of the units to cause a higher wiring cost.
The integrated ground system is principally employed in the United States of America and others, and each of the grounds within the communication system is connected to a CG within a power distributing apparatus (see
FIG. 16
) which in turn, is connected to an FG of an exchange system. Further, the CG in the power distributing apparatus is connected as a power supply return in the power room to a rectifier.
This integrated ground system does not require the leading of the SG from the communication system to the external but requires only a connection of the FG of the power distributing apparatus to a neighboring FG of, for example, an exchange system, and therefore, the ground line wiring work is facilitated to decrease the wiring work cost, and the requirement to the electric insulation of the communication system from the station house building does not necessarily exist, and hence, a spanning cable rack or the like of the communication system is not needed to be electrically insulated from the station house constructing materials, which facilitates the associated works and lowers the wiring work cost, so that its construction cost becomes lower than that of the aforesaid isolated ground system. However, when being used for a large-scale communication system, this integrated ground system shows a disadvantage of being poor at noises because, at the falling of a thunderbolt, the thunderbolt noises are introduced through a shield for signal cables existing between spanning rows into the building.
The selection between the isolated ground system and the integrated ground system depends upon the standard ruled by the nation employing the communication system, and the ground system meeting the standard by that nation is chosen, whereupon a power distributing apparatus and a communication system are produced accordingly.
In the case of a power distributing apparatus equipped with such a prior breaker apparatus, since difficulty is experienced to perform the extension of the NFB or the like resulting from the enlargement of the power-supply capacity, as mentioned before, in the design of the power distributing apparatus, in consideration of the future extension of the exchange system or the like, the power-supply ability per one rack column, and in its turn the breaker capacity, is designed on the basis of the maximum number of racks in the station.
Accordingly, the power distributing apparatus with the prior breaker apparatus is constructed to provide a breaker capacity corresponding to the maximum power-supply ability at all the time, with the result that the manufacturing cost of the power distributing apparatus increases. Further, in a small-scale communication system (small station system), the rate of the cost of the power distributing apparatus to the total system cost rises, and the rise of the power distributing apparatus cost hinders lowering the total system cost, thus reducing the cost advantage on the market when being applied to a small station system.
Furthermore, in the recent years, with the improvement of the functions of the units constituting a communication system, its densification advances, with the result that the power consumption increases in units of units or in units of racks, and hence, since a consideration should be given to a power-supply ability covering this increasing power consumption at the above-mentioned design of the power distributing apparatus, the power-supply capacity of the power distributing apparatus further increases to further heighten the manufacturing cost of the power distributing apparatus.
Still further, although the communication system is required to undergo maintenance without stopping and, hence, its power supply system employs a double-powered construction, in the case of a power distributing apparatus equipped with a prior breaker unit, the replacement of the NFB or the extension of the power distributing apparatus requires that the power supply to the distribution board to be replaced is turned off or that the work for the replacement or the extension is done risking the short-circuit accident in the hot-line condition without turning off the power supply, which creates a problem in the stabilization of the system operation.
Besides, since the NFB is attached through screws to the power distributing apparatus, there is a problem in that the replacement work efficiency of the NFB deteriorates.
Moreover, because the determination as to whether the ground system is constructed as the isolated ground system or as the integrated ground system relies upon the standard taken by the nation installing the communication system and the power distributing apparatus is to be manufactured to be conformable to that nation, there is a problem in that difficulty is encountered to commonly use the products, which causes the increase in the number of parts so that the manufacturing cost goes up.
SUMMARY OF THE INVENTION
The present invention has been developed with a view to eliminating the above-mentioned problems, and it is therefore an object of this invention to provide the improvement of constructions of a breaker apparatus and breaker unit which is capable of not only constituting a power distributing apparatus with a necessary but minimized const
Etou Mitsuru
Kanemaru Yasuhisa
Murata Yasunori
Oomori Kazunori
Tobimatsu Yoshiaki
Barrera Ramon M.
Fujitsu Limited
Katten Muchin Zavis & Rosenman
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