Methods of arc suppression and circuit breakers with electronic alarmers

A circuit breaker with PTC element and sequential breaking comprising:

• a case,
• a first pair of contacts connected in series with a circuit,
• a metallic PTC element connected in parallel with said first pair of contacts, the resistivity of said metallic PTC element at its melting point being at least 5 times its room temperature resistivity,
• a second pair of contacts connected in series with said metallic PTC element and in parallel with said first pair of contacts,
• means to separate said first pair of contacts when a short circuit or an overload occurs in said circuit, and
• means to separate said second pair of contacts one to ten millisecond after the opening of said first pair of contacts during a circuit interruption.

A circuit breaker for protection from not only a short circuit and an overload, but also a ground fault comprising:

• a case,
• a pair of electrical contacts,
• a ground fault-detector coil,
• a trip coil and a series coil around the same core,
• a thyristor mounted on a circuit board and connected to said fault-detector coil and said trip coil,
• means to separate said contacts with the attraction of said trip coil or said series coil when a ground fault or a short circuit occurs respectively, and
• means to separate said contacts when an overload occurs.

A circuit breaker with an electronic indicator of a fault current comprising:

• a case,
• a pair of main contacts,
• means to separate said main contacts when said fault current occurs,
• a pair of small contacts,
• means to give a force when said fault current occurs,
• means to close said pair of small contacts only by said force and to keep said pair of small contacts closed even after said pair of main contacts being automatically opened because of said fault current,
• means to give an electronic signal by a small current when said pair of small contacts are closed, and
• means to open said pair of small contacts when said main contacts are reclosed.