Patent ID: 8754730

Claim:
An electromagnetically operated switching device comprising: electromagnetically operated mechanisms for opening/closing a main circuit contact of a switch; a link mechanism for transmitting operation forces of the electromagnetically operated mechanisms to the main circuit contact of the switch; a driving rod that is arranged along an operational center axis of the main circuit contact; a contact-pressure spring that is disposed around the driving rod and applies a necessary contact pressure to the main circuit contact; a spring retaining plate linked to the driving rod so as to retain the contact-pressure spring; wherein the link mechanism includes an interlocking link for transmitting a stroke of the electromagnetically operated mechanisms, a first link rotatably linked to the interlocking link, a second link rotatably linked to the spring retaining plate, and a driving lever with one end portion rotatably linked to a support point of a fixing plate and an other end portion of the driving lever rotatably linked to the second link; a length from an operational center axis of the spring retaining plate to a link point linking the spring retaining plate with the second link is configured in accordance with a change of a link ratio for the link mechanism; and wherein the link ratio for the link mechanism is a ratio between a length from the support point of the fixing plate to a link point linking the second link with the other end portion of the driving lever, and a length from the support point of the fixing plate to a link point for linking the first link with the driving lever.