Title:
MONITORING CIRCUIT FOR MINUTE OVER CURRENT
Document Type and Number:
Japanese Patent JP3116882
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To detect an abnormal overcurrent to appear immediately before the occurrence of a fault and to improve both reliability and safety by comparing and determining a differential addition value calculated from an average load correct.
SOLUTION: An average load current Zn is calculated by an average load current calculator 4 and then subtracted from the precedent average load current Zn-1 by a deviation calculator 5 to determine a differential value Hn. The value Hn is added to the precedent difference value Hn-1 that is calculated by an addition deviation calculator 6 to determine a difference addition value K. The value K is compared with a prescribed allowance value 8 by a comparison/decision device 7. Thus, a normal load current is determined if the value K is smaller than the value 8. Then the current Zn-1 is updated to the current Zn for calculation of a new difference, and the similar operation is repeated. If the value K is equal to or larger than the value 8, it is determined as an overload abnormal current. Then a warning signal is outputted from the device 7.
Inventors:
Nagao straight string
Application Number:
JP31094297A
Publication Date:
December 11, 2000
Filing Date:
November 12, 1997
Export Citation:
Assignee:
NEC
International Classes:
G01R19/12; G01R19/165; G05F1/00; G05F1/10; H02H3/00; H02H3/02; (IPC1-7): G05F1/10; G01R19/12; G01R19/165
Domestic Patent References:
| JP10336877A |
Attorney, Agent or Firm:
Yutaro Kumagai