Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
2000-11-22
2002-11-05
Le, N. (Department: 2858)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S509000
Reexamination Certificate
active
06476618
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a power abnormality indicating circuit, and especially to circuit for indicating abnormality of a three-mode surge absorber of a public electric power. Other than indicating the abnormality of the L-N, L-G, N-G surge absorbing devices, the present invention can prevent current leakage as destroys occurs in above modes.
BACKGROUND OF THE INVENTION
The general power receptacles for surge protection use metal oxide varistors or other transient/surge absorbers for suppressing surge wave. These elements will heat as absorbing surge wave, even a large surge wave will induce a short circuit. Therefore, temperature fuses or current fuses are used to prevent abnormality.
In general, the cutting-off of fuses is used to determine the abnormality of a surge protection indicator. However, in order to prevent that the leakage current to the ground is too large, in general, the indicator only displays the condition of the input ends of line-neutral mode while the conditions of line-ground mode and neutral-ground mode are not displayed.
Referring to
FIG. 1
, a prior art circuit for indicating abnormality of a surge absorber is illustrated, which includes two surge absorbing devices
10
and
30
and an abnormal indication circuit
20
. The L-N end in the three-mode in public power supply is connected to the surge absorbing device
10
in series. The surge absorbing device
30
is serially connected between the L-G and N-G ends. The surge absorbing device
10
has a two-end temperature sensing fuse
101
capable of suffering from a temperature of 139° C. and a metal oxide varistor
102
. When the metal oxide varistor
102
has abnormality, it will heat gradually. Since it tightly resists against the two-end temperature sensing fuse
101
, the metal oxide varistor
102
will heat and finally burn-cut the two-end temperature sensing fuse
101
so that the surge protection indicator D
2
will extinguish due to no current flowing therethrough.
The surge absorbing device
30
has two metal oxide varistors
301
and
302
and a two-end temperature sensing fuse
303
capable of suffering from a temperature of 139° C. When the metal oxide varistor
301
has abnormality, it will heat gradually. Since it tightly resists against the two-end temperature sensing fuse
303
, the metal oxide varistor
301
will heat and finally burn-cut the two-end temperature sensing fuse
303
, but the two-end temperature sensing fuse
101
does not burn-cut so that the surge protection indicator D
2
will not extinguish. Namely, the fault of the surge absorbing device
30
of the L-G ends can not be detected. Furthermore, When the metal oxide varistor
302
has abnormality, it will heat gradually. Since it tightly resists against the two-end temperature sensing fuse
303
, the metal oxide varistor
302
will heat and finally burn-cut the two-end temperature sensing fuse
303
, but the two-end temperature sensing fuse
101
does not burn-cut so that the surge protection indicator D
2
will not extinguish. Namely, the fault of the surge absorbing device
30
of the N-G ends can not be detected.
SUMMARY OF THE INVENTION
Accordingly, the primary object of the present invention is to provide a circuit for indicating abnormality of a three-mode surge absorber and a multiple-end fuse.
To achieve above objects, the present invention provides a circuit for indicating abnormality of a three-mode surge absorber of a public electric power serially connected to an input end and an output end of a public power supply, the circuit for indicating abnormality of a three-mode surge absorber of a public electric power comprising: a first two-end fuse having a first end coupled to the line input end; a first surge absorbing device coupled to a second end of the first two-end fuse and the neutral input end for absorbing a surge between the line input end and the neutral input end; a second surge absorbing device coupled to the line input end and the neutral input end for absorbing a surge between the neutral input end and ground input end; an abnormal indication circuit coupled to the first surge absorbing device, the second surge absorbing device and the neutral input end for indicating abnormalities in three-mode of a public power supply; and a second two-end fuse having a first end coupled to the second surge absorbing device, and a second end coupled to the ground input end for preventing abnormalities of parts. By the aforesaid circuit, other than indicating the abnormality of the L-N, L-G, N-G surge absorbing devices, the present invention can prevent current leakage as destroys occurs in above modes.
The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing.
REFERENCES:
patent: 5299088 (1994-03-01), Honi et al.
patent: 6166458 (2000-12-01), Redburn et al.
Le N.
LeRoux Etienne P
Troxell Law Office PLLC
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