The selection of ac contactor and operation maintenance

 (1) to electrical motor choose:(1) rated current of the primary loop contacts should be greater than or equal to the rated current,accused of equipment control motor contactor should also be considered the starting current of the motor.In order to prevent frequent operation of contactor main contact ablation,frequent movement of contactor rated current can reduce use.(2) the electromagnetic contactor coil rated voltage is 36 v,110 v,220 v,380 v,the electromagnetic coil allows within the scope of 80%~105% of rated voltage.(2) operation maintenance:(1) check in the operation of the project:1) by the load current is within the contactor ratings;2) contact points and the signal is consistent with the circuit state;3) running sound acmotortrading.blogspot.com is normal,have because poor contact and heat discharge;4) with or without electromagnetic coil overheating electromagnet short-circuit rings with and without exception.5) arcing cover any loose and damage;6) auxiliary contact with and without damage;7) transmission part with and without damage;8) have running environment without adverse factors of running around,such as too much vibration is too large,poor ventilation,dust,etc.

(2) maintenance:in electrical equipment maintenance work,to maintain the contactor shall work.1) external maintenance:a.external dust cleaning;B.check all fasteners are loose,especially the conductor connection parts,prevent loose contact and fever;2) contact system maintenance:a.check of dynamic and static contact position is,whether the three-phase closed at the same time,the contact spring should be adjusted if you have any questions;B.check contact wear,wear depth shall not be more than 1 mm,contact burning,welding off,must be change in time;When slight loss,generally does not affect the use.Clean the contact is not allowed to use sand paper,should use the plastic file;C.and measuring insulation resistance,electrical motor resistance of not less than 10 m Ω;D.check whether the auxiliary contact action is flexible,contact schedule should comply with the specified value,check whether there is any loose fall off on contact,found the problem,should be timely repair or replacement.3) maintain core parts:a.cleaning the dust,especially the moving parts,and between the core and interface;B.check the fastening situation of iron core,iron core run loose cause noise increase;C.core end ring have fall off or break to repair in time.4) electromagnetic coil maintenance:a.measuring coil insulation resistance;B.the coil insulation discoloration,aging,coil surface temperature should not exceed 65 ° C;C.check the coil wire small electric motors connection,if there are any open welding,burning loss should be timely repair.5) arcing cover parts maintenance:a.check whether the arcing cover is damaged;B.arcing cover any loose and location changes;C.remove arcing cover gap within the metal particles and sundry.


(3) working principle of the vacuum contactor,vacuum contactor with vacuum arcing medium,its main contact seal in a special vacuum arcing tube.When operating coil electricity,armature,absorption in the contact spring and vacuum tube autistic force under the action of contact closure;Operating power coil,the armature reaction spring overcome vacuum tube autistic force release,off contact.Contactor breaking current,the contact gap formed by metal vapor can be formed in the platinum scale,affect the service life of the contactor.