| 摘要 |
PURPOSE:To detect the wear state of a contact electrically at low cost by providing a reference contact which is made with specific time delay associatively with the contact to be monitored and deciding the life limit of the contact when both contacts are made at the same time. CONSTITUTION:An electromagnetic coil 13 is fed with electricity at time t0 in the beginning of the use of the contact 11, the reference contact is made at time t2 which is a time T0 later. The contact 11, however, is already made at time t1 before it. Then the time difference between the time t1 and time t2 is a set time difference T1. When this contact 11 is made and broken many times repeatedly to reach a specific wear quantity, feeding electricity to the electromagnetic coil 13 at time t3 makes the contact 11 and reference contact 12 at the same time at time t4 which is the time T0 later. Namely, the making time difference between the contact 11 and reference contact 12 becomes 0 and the making time difference of the further wearing of the contact 11 is inverted. When this time difference is 0, the life limit or life warning limit of the contact 11 is decided. |
