公开(公告)号：JPH08214448A

公开(公告)日：1996-08-20

申请号：JP30160595

申请日：1995-11-20

Applicant: ABB MANAGEMENT AG

Inventor： TOUDOORU BAIATSU

IPC: H01C1/08 ,  H01C3/12 ,  H02H7/12 ,  H02H9/02 ,  H02M7/487

Abstract: PROBLEM TO BE SOLVED: To confine the short circuit current within the damage limit of a passive element in an electric facility or a circuit to be protected by additionally connecting at least one electrical resistance in series with at least one varistor in a second current branch. SOLUTION: A PTC thermistor 5 in a main current path is connected in parallel with a shunt resistance branch 6, comprising a series circuit of a varistor 7 and an ohmic resistor 14. Upon the occurrence of trouble or short circuit, the PTC thermistor 5 is heated over the response temperature thereof, and the resistance thereof is increased significantly thus limiting the current flow. The PTC thermistor 5 is protected against thermal damages, because the short circuit current is diverted to the shunt resistance branch 6. In other words, the current limiting characteristic of the circuit are enhanced through the ohmic resistor 14 which is connected in series with the varistor 7.

公开(公告)号：JPH09149549A

公开(公告)日：1997-06-06

申请号：JP30160695

申请日：1995-11-20

Applicant: ABB MANAGEMENT AG

Inventor： TOUDOORU BAIATSU

IPC: H02H9/02 ,  H02H9/04

Abstract: PROBLEM TO BE SOLVED: To restrain a short-circuit current to be at most the breakdown limit of an electric device or passive elements of a circuit which are to be protected, by connecting a PTC resistor with a parallel circuit to a varistor of a bypass resistor branch. SOLUTION: A bypass resistor branch 6 is connected in parallel with a PTC resistor 5 via a main current circuit. The bypass resistor branch 6 is a series circuit constituted of a varistor 7, an ohmic resistor 8, and a choke or an inductor 30. In the case of an error or a short circuit, the PTC resistor 5 generates heat, and exceeds its response temperature. As a result, the resistance of the PTC resistor 5 is largely increased, and limits a current. A short-circuit current is made to flow in the bypass current branch 6, so that thermal breakdown of the PTC resistor 5 is avoided. Thereby the short-circuit current can be limited within 10μs, i.e., the value lower than or equal to the breakdown limit of an electric device or passive elements of a circuit which are to be protected.

公开(公告)号：JPH08213204A

公开(公告)日：1996-08-20

申请号：JP30160395

申请日：1995-11-20

Applicant: ABB MANAGEMENT AG

Inventor： TOUDOORU BAIATSU

IPC: H01C1/08 ,  H01C1/082 ,  H01C7/02 ,  H02H9/02

Abstract: PROBLEM TO BE SOLVED: To reversibly operate a protective device and enable response without arc, by a method wherein a second main surface of a resistive track receives pressure by a pressure compensation element which is an insertion member of a polymer film. SOLUTION: An insulating or ceramic layer 20 comes into contact electrically with a metal cooling element 25, through a first main surface. A bent track 16 of a resistor of a PTC thermistor 5 is pressed against the part between a thermally conductive layer 21 and a highly stable polymer film 22. On the track 16, a pressure compensation cushion or a pressure compensation element 23 wherein a force F is applied rectangularly to a second main surface of the ceramic layer 20 is arranged. Thereby a power source limiter is obtained which carries a continuous current of at least 100 A, and limits a short-circuit current, within 10 μs, down to a value lower than the breakdown limit of a passive component of an electric apparatus or a circuit which are to be protected.