Tokyo Shibaura Denki Kabushiki Kaisha

Takayuki Kobayashi

Fumio Andow

Ryotaro Kondow

Yoshiji Nii

Shigeru Suzuki

In a digital protective relaying device for protecting electric power transmission line including an electric station at each end thereof, and each electric station including at least one circuit breaker to be tripped by a protective relay for protecting the own station, a digital protective relay provided with a computer is further provided at each end so as to receive electrical data in digital form from the electric stations for operating in an ordinary protective operation. As a control condition occurs in one station, the condition is sent to a digital protective relay provided at the other end of the transmission line, thereby changing the operational steps of the computer included in the protective relay.

Digital protective relaying systems

A static circuit comprising an input transformation circuit responsive to current or voltage derived from an electric power system to be protected for producing a first pair of electric quantities having a phase difference of .theta. and a second pair of electric quantities dephased by .phi. from the first pair of electric quantities respectively, a pair of multipliers for the producing products of the first and second pair of electric quantities, and an adder or subtractor for producing the difference of these products.

Growing community of inventors

Fuchu, Japan

Takayuki Kobayashi