Contact-force setting circuit for E-M relay - has motor driving force sensor against moving contact spring, and force signal is digitised

摘要

The contact-force setting circuit, for electromagnetic relays, has a sensor drive motor (M1) started by a start button (T) via a control circuit (MSt). A force sensor is held against the moving contact spring until this contact has moved away from the fixed contact as determined by the opening of the break contacts (7). The drive motor is switched off and the force sensor stops. At the same time an analog signal proportional to the contact force is obtained from a transformer and digitalised for determining whether it lies within the prescribed limits.