Electrical switch with three fixed contacts, a rotating knife contact and three switch positions

An electrical switch comprising:

• a first fixed contact,
• a second fixed contact,
• a third fixed contact,
• a rotatable knife contact being connected with a permanent electrical connection to the third fixed contact, the rotatable knife contact comprising at least one longitudinal pair of blades flexibly connected to each other with a spring structure, the rotatable knife contact having a first switching position in which a first outer end of the blades makes contact with the first fixed contact connecting only the first fixed contact and the third fixed contact electrically to each other, and a second switching position in which a second outer end of the blades makes contact with the second fixed contact connecting only the second fixed contact and the third fixed contact electrically to each other,
• a contact portion of the first fixed contact comprises a contact area having the form of an arc and a contact portion of the second fixed contact comprises a contact area having the form of an arc, the outer ends of the blades of the rotatable knife contact making contact with said contact areas during the switching operation of the electrical switch,
• the rotatable knife contact has further a zero switching position between the first switching position and the second switching position in which zero switching position the first outer end of the blades makes contact with the contact area of the contact portion of the first fixed contact and the second outer end of the blades makes contact with the contact area of the contact portion of the second fixed contact connecting the first fixed contact, the second fixed contact and the third fixed contact electrically to each other.