접촉기,회로 차단기,태양광 인버터,전기 계량기,태양 전지
Common faults of LS contactors for elevators (taking MC-18b as an example) are mainly concentrated in three core modules: contact system, electromagnetic system, and mechanical structure, accompanied by corresponding abnormal operation phenomena. The specific classification and manifestations are as follows:
- Contact System Faults (Most Frequent)
Contacts are the core components of contactors that carry the current of the main circuit, and their faults directly affect the reliability of circuit on-off control. Common fault types are as follows:
- Contact Ablation and Oxidation
Manifestations: The surface of main contacts appears blackened, pitted, and carbon-deposited; the contact resistance of auxiliary contacts increases. During elevator operation, motor start-stop delay or local overheating of the control cabinet may occur.
Causes: Current overload, continuous arc discharge, wear of silver alloy contact materials, or repeated impact on contacts caused by frequent start-stop of elevators.
- Contact Welding and Adhesion
Manifestations: After the contactor coil is de-energized, the main contacts cannot disconnect, resulting in failure of the elevator motor’s “brake holding” function or continuous operation of the motor. In severe cases, it will trigger the overload protection of the control system.
Causes: Instantaneous high-current impact caused by short-circuit faults, or local melting and adhesion of contacts after long-term ablation.
- Poor Contact of Auxiliary Contacts
Manifestations: The elevator control system frequently reports “contactor status abnormality” faults, or the auxiliary circuits such as door motors and lighting are intermittently connected and disconnected. The PLC cannot accurately identify the pull-in/release status of the contactor.
Causes: Fatigue of auxiliary contact springs, 접촉 산화, or loose wiring terminals during installation.
- Electromagnetic System Faults
The electromagnetic system is responsible for driving the pull-in and release of the contactor, and its faults will directly cause the contactor to fail to operate normally:
- Coil Burnout or Open Circuit
Manifestations: The contactor has no response and cannot pull in after being energized. Measuring the coil resistance with a multimeter shows an infinite value, or the coil housing emits a burning smell and the insulation layer cracks.
Causes: Excessively high/low control voltage, aging of the coil due to long-term energization and heating, or short circuit caused by water ingress into coil lead terminals.
- Shading Ring Fracture
Manifestations: The contactor emits a strong buzzing and jittering noise when pulling in, with loud noise and core vibration. During elevator operation, the contactor is prone to unstable contact due to vibration.
Causes: Mechanical impact during core pull-in, or extrusion of the shading ring caused by housing deformation during installation.
- Foreign Objects or Rust on Core Contact Surfaces
Manifestations: The contactor cannot pull in completely, with gaps between the iron cores. Even if the coil is energized, the main contacts cannot close fully, resulting in excessive voltage drop in the main circuit.
Causes: Dust and metal debris in the control cabinet entering the core contact surfaces, or core rust caused by a humid environment.
III. Mechanical Structure Faults
Mechanical components are responsible for transmitting electromagnetic force and ensuring the synchronization of contact actions. Faults are mostly caused by wear and fatigue:
- Spring Fatigue or Fracture
Manifestations: After the coil is de-energized, the contactor releases slowly (with a delay exceeding 0.5s) or cannot reset completely. Insufficient contact pressure during pull-in is prone to arc generation.
Causes: Elastic attenuation of reaction springs and release springs due to long-term frequent actions, or aging of spring materials.
- Transmission Mechanism Jamming
Manifestations: The contactor’s pull-in/release actions are stuck or even fail to operate. There is high resistance when manually pushing the movable iron core.
Causes: Component misalignment caused by housing deformation or loose mounting screws, or dust entering mechanical gaps.
- Housing and Terminal Damage
Manifestations: Cracks in the housing invalidate the IP20 protection rating, allowing dust and moisture to enter the interior. Thread slipping and ablation of terminals, as well as loose wiring, lead to local overheating.
Causes: Rough operation during installation, excessive vibration of the control cabinet, or long-term overcurrent heating of terminals.
- Fault Summary and Prevention
Faults of elevator contactors are mostly related to frequent start-stop, harsh working conditions, and improper maintenance. Daily maintenance should include regular cleaning of contacts and core contact surfaces, inspection of coil voltage, and tightening of wiring terminals. Preventive replacement should be carried out in a timely manner when the rated service life is reached to avoid the expansion of faults affecting the safe operation of elevators.
