Abstract Apparatus for detecting abnormal conditions of an AC source comprises first and second Schmitt trigger circuits respectively responsive to first and second levels of the rectified voltage of the source voltage, a first monostable circuit responsive to the end of the output pulse from the second Schmitt trigger circuit for producing a pulse of a constant width which is longer than the spacing between output pulses from the second Schmitt trigger circuit at the normal frequency of the source, a bistable circuit which is set at the beginning of the output pulse from the first Schmitt trigger circuit and reset at the end of the output pulse from the first monostable circuit, a second monostable circuit responsive to the beginning of the output pulse from the second Schmitt trigger circuit for producing a pulse of a constant width which is longer than the spacing between output pulses from the bistable circuit at the normal frequency of the source and a gate circuit responsive to the output pulses from the bistable circuit and the second monostable circuit for producing an abnormal signal in the absence of these two output pulses.
Inventors
👤 Yutaka Tochitani
Bibliographic Details
Application Number—
JurisdictionUS
Data Sourcegoogle_patents
Last Synchronized2026-10-25 14:19
CPC Classifications
H; H02; H02H; H02H3/00; H02H3/24; H02H3/46
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
235 words
Apparatus for detecting an abnormal condition of an AC source comprising a rectifier to rectify the voltage of said AC source; a first Schmitt trigger circuit to produce a pulse at a first level of the rectified voltage; a second Schmitt trigger circuit to produce a pulse at a second level of said rectified voltage; said second level being lower than said first level; a first monostable circuit responsive to the end of the output pulse from said second Schmitt trigger circuit for producing a pulse of a constant width which is longer than the spacing between output pulses from said second Schmitt trigger circuit when the frequency of said source voltage is normal; a bistable circuit which is set at the beginning of the output pulse from said first Schmitt trigger circuit and reset at the end of the output pulse from said first monostable circuit; a second monostable circuit responsive to the beginning of the output pulse from said second Schmitt trigger circuit for producing a pulse of a constant width which is longer than the spacing between output pulses from said bistable circuit when the frequency of said source voltage is normal; and a gate circuit responsive to the output pulse from said bistable circuit and the output pulse from said second monostable circuit for producing an abnormal signal in the absence of said two output pulses supplied to said gate circuit.
Claim 2
Dependent Claim
235 words
Apparatus for detecting an abnormal condition of an AC source comprising a rectifier to rectify the voltage of said AC source; a first Schmitt trigger circuit to produce a pulse at a first level of the rectified voltage; a second Schmitt trigger circuit to produce a pulse at a second level of said rectified voltage; said second level being lower than said first level; a first monostable circuit responsive to the end of the output pulse from said second Schmitt trigger circuit for producing a pulse of a constant width which is longer than the spacing between output pulses from said second Schmitt trigger circuit when the frequency of said source voltage is normal; a bistable circuit which is set at the beginning of the output pulse from said first Schmitt trigger circuit and reset at the end of the output pulse from said first monostable circuit; a second monostable circuit responsive to the beginning of the output pulse from said second Schmitt trigger circuit for producing a pulse of a constant width which is longer than the spacing between output pulses from said bistable circuit when the frequency of said source voltage is normal; and a gate circuit responsive to the output pulse from said bistable circuit and the output pulse from said second monostable circuit for producing an abnormal signal in the absence of said two output pulses supplied to said gate circuit.
Claim 3
Dependent Claim
27 words
The apparatus according to claim 1 wherein the output pulse from said second monostable circuit disappears when the output pulse from said second Schmitt trigger circuit disappears.
Claim 4
Dependent Claim
50 words
The apparatus according to claim 1 which further comprises a third Schmitt trigger circuit responsive to a third level of said rectified voltage which is higher than said first level, the output pulse of said third Schmitt trigger circuit being utilized to reset said bistable circuit at the beginning thereof.