Electricity: electrical systems and devices – Safety and protection of systems and devices – Series connected sections with faulty section disconnect
Patent
1986-10-16
1988-06-14
Pellinen, A. D.
Electricity: electrical systems and devices
Safety and protection of systems and devices
Series connected sections with faulty section disconnect
361 64, H02H 303, H02H 726
Patent
active
047516046
ABSTRACT:
A protective relay, for use in protecting a predetermined protected zone of a three phase alternating current electrical power transmission line, the relay being of the type which receives a comparison signal from a remote relay by way of a communication channel, includes circuitry for detecting abnormalities in the received comparison signal. Such abnormalities are caused by, for example, errors in the communication channel, non-fundamental frequency components in the secondary current caused by current transformer saturation, and high frequency transients in the protected zone. The abnormalities are detected by subtracting a filtered demodulated signal having a frequency which is substantially equal to a fundamental frequency of the comparison signal, from an unfiltered demodulated signal. The resulting difference is a signal which comprises components caused by the abnormalities. The resulting difference signal is utilized as a restraint signal to prevent the protective relay from incorrectly generating a circuit breaker trip signal. The filtered demodulated signal is utilized as an operate signal, in conjunction with a locally generated operate signal, to produce circuit breaker trip signals.
REFERENCES:
patent: 4056838 (1977-11-01), Leib
patent: 4275429 (1981-06-01), Church et al.
patent: 4408246 (1983-10-01), Ray
patent: 4420788 (1983-12-01), Wilkinson et al.
patent: 4464697 (1984-08-01), Sun
patent: 4524446 (1985-06-01), Sun et al.
Paper entitled "Utility Fiber Optic Applications" by Patterson et al., presented to Thirty-Eighth Annual Texas A&M Relay Conference, College Station, Texas, Apr. 22-24, 1985.
Deboer Todd E.
General Electric Company
Murray William H.
Pellinen A. D.
Policinski Henry J.
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