1. No release of power loss surface
The normal rated voltage of the coil can be directly measured from the terminal of the coil with a multimeter. There are two possible situations: the voltage is zero and does not close
1) The armature and the driven moving parts are stuck, such as foreign matter falling into the gap of the moving parts; The armature can not move due to the coil body heating deformation, and the cage can not move due to the contact overheating.
2) When the current of the contact exceeds several times of its own capacity, the dynamic and static contacts can be sintered together and cannot be released. This fault often occurs in the normally open contacts.
2. Power on without closing
The normal rated voltage can be directly measured from the terminal of the coil with a multimeter without closing
1) The coil body is not electrified
This is because there is a small section of thin lead wire from the terminal to the coil body, which is broken due to oxidation and repeated mechanical vibration (mechanical vibration will occur during pull-in and release).
2) The armature and the driven moving parts are stuck, such as foreign matter falling into the gap of the moving parts; The heating of the coil body causes the deformation of the frame, which makes the armature unable to move, and the overheating of the contact causes the deformation of the cage, which makes the moving parts unable to move.
3) The coil body is damaged.
4) When the current of the contact exceeds several times of its own capacity, the dynamic and static contacts can be sintered together and cannot be closed. This fault often occurs in normally closed contacts.