维修保养-ABB接触器维护.docx

ABB接触器维护Maintenance of contactsA contact is not necessarily damaged or worn out, just because the surface is rough and discolored. The contacts in the figure below may look like bad contacts but the fact is that they are better than a new set of contacts. This is because they are ”electrically seated”and make good contact over a larger surface. Based on this it would be completely wrong to change a contact only by judging from the appearance of the surface. Also it is quite normal that the contacts in the three phases are not evenly worn and because of this all contacts both fixed and movable need to be changed. At the same time it is recommended to change the arc chutes.Inspection of contactsWith today′s high performance contactors, filing, grinding, or other attempts to restore contacts or contact surfaces should be avoided. Our experience shows that filing and grinding increases the risk of causing other problems. For example the risk of increasing the contacts resistance is high due to scrap from this grinding and filing.Maintenance should be limited to inspection of the contacts for the level of contact wear.This is to ensure a trouble free operation of the contactor until the next service is required (see next section –Interpreting levels of electrical contact wear). At the same time observations can be made to judge if the contactor operates well in the application and that no signs of abnormal wear or damages are present on the contacts.1. The appearance of contacts after a very low number of operation in an AC-3 application2. A contact just having reached a ‘good worn in’ level in an AC-3 applicationInterpreting levels of electrical contact wearGeneralBasically these contactors are considered maintenance free. Depending on the severity of the application contact inspection may be required. A typical severe application would involve frequent making and breaking of high currents, reversing and inching (AC4). Premature service on contactors will increase the o