Protective device

An electrical circuit comprising:

• a prescribed electrical element to be protected;
• a first electromotive force source for providing electrical power to the prescribed electrical element;
• a circuit protection device connected electrically in series intermediate the the prescribed electrical element and the first electromotive force source for protecting the prescribed electrical element, the circuit protection device comprising:
• a bimetal switch including a first PTC member and a bimetal member connected electrically in a parallel with each other;
• and
• a second PTC member disposed adjacent the bimetal switch;
• the electrical circuit further comprising a switch and a second electromotive force source connected electrically in series with the second PTC member, wherein the switch is configured to detect a potential difference in the prescribed first electrical element and to switch to a closed position when the potential difference exceeds a predefined threshold, thereby supplying current from the second electromotive force source to the second PTC member to cause tripping of the second PTC member;
• the bimetal member being disposed to be actuated by tripping of the second PTC member;
• wherein the second electromotive force source is electrically independent of the first electromotive force source.