Abstract: The Disclosed is a solenoid valve, in which a rod is moved by a plunger that comes into contact with and separates from a stator by electromagnetic force, causing a valve body that opens and closes a valve to move reciprocally. The valve is configured such that a first space and a second space are formed at respective sides of the plunger in the movement direction thereof, a through-hole is formed in the plunger so as to be concentric with a center axis, the rod is arranged in the first space, and a communication passage is formed between an inner surface of the plunger and an outer surface of the rod and communicates with the first space S1 and the second space.

Abstract: A zero-phase sequence current detector have three circular cores provided around three phases overhead lines of AC power lines, three magnetoptic sensors provided on respective cores for detecting currents flowing on respective power lines, and a processing circuit containing an adding circuit for adding outputs of the magnetoptic sensors and a compensation processing circuit for canceling erroneous components due to the differences of the temperature characteristics among the magnetoptic sensors.

Abstract: The disclosed porcelain insulator has built-in optical transmission media extending therethrough from a base metal secured at one end thereof to a conductor-holding fixture at the opposite end thereof. The conductor-holding fixture may carry one or both of two type sensing units: namely, a sensing unit having a current transformer (CT) coupled to the phase conductor, a load resistor connected to the CT, and an electro-optic element coupled to both said load resistor and said optical transmission medium; and another sensing unit having a capacitive potential transformer (PT) coupled to said conductor and an electro-optic element coupled to both said PT and said optical transmission medium.

Abstract: The disclosed porcelain insulator has built-in optical transmission media extending therethrough from a base metal secured at one end thereof to a conductor-holding fixture at the opposite end thereof. The conductor-holding fixture may carry one or both of two type sensing units: namely, a sensing unit having a current transformer (CT) coupled to the phase conductor, a load resistor connected to the CT, and an electro-optic element coupled to both said load resistor and said optical transmission medium; and another sensing unit having a capacitive potential transformer (PT) coupled to said conductor and an electro-optic element coupled to both said PT and said optical transmission medium.