A magnetic starter is a device designed for switching power electrical circuits. The first thing to do before servicing or repairing a magnetic starter is to study the documentation for this starter, or, as they do in the 21st century, look on the Internet. It is also worth knowing the weak points of magnetic starters - contact groups. It is the contact groups that need careful examination. It is worth paying attention to the fastening elements and the body, which will be discussed in the article.
External inspection
The repair of the magnetic starter begins with an external inspection. External inspection involves inspection of the body and fasteners for cracks, chips. If there are cracks on the fasteners, this affects the volume of work, and also, if the starter falls off and its “toad” design, then there is a danger that it will turn on the power circuit. In addition, attention should be paid to protectivelids.
It is also worth inspecting the starter for contamination. If there is a large amount of dust, oils, traces of liquid (crystalline growths) and other aggressive elements on the case, then it is worth reconsidering the method of protecting the starter from aggressive environmental influences. Increase the degree of dust and moisture protection. If this is not done, then the coil in the starter, which will be described later, will quickly become damp and fail, and the metal parts will corrode.
Contact groups
Basically, maintenance and repair of magnetic starters comes down to contact groups. To inspect them, you need to open the protective cover, the first thing we pay attention to is the contact groups. If there is a slight soot, then you need to clean it off with a fine-grained sandpaper. As you can see in the photo, there is no oxidation. This means that the selected method of protecting the starter from aggressive environmental factors is chosen correctly.
If traces of oxide, darkening, rust are visible on the metal parts, then in this case it is necessary to unequivocally reconsider the method of mounting the starter. Or rather, install it in a more dust- and moisture-proof shell. Then we inspect the contact groups for the presence of soot, deposits, shells. Depending on the degree of damage to the contact groups, a decision is made to repair or replace.
Example of faulty moving contacts to be replaced
The photo above shows a "survivor" after a shortclosing contact. The remaining two are out of order and need to be replaced.
Repair of contactors and magnetic starters often comes down to the repair of contact groups. This is done by cleaning the soot from the contact pad. If during the inspection shells, overflows are found, then these places need to be leveled with a flat small file or needle file. This is done in the same plane with the pad of the fixed contact. For a better effect, you can grind both contact pads on the movable and fixed elements.
It is highly not recommended to do all these operations with sandpaper or sandpaper, since in this case it is very difficult to maintain a plane. An unsteady plane means a reduction in the contact area, and this in turn causes excessive heating and premature failure of the magnetic starter. It is worth inspecting both the main and auxiliary contact groups.
Anchor and electromagnet
The armature and the magnetic circuit of the magnetic starter rarely suffer, but sometimes it happens that the package in which the sheets of cold-rolled anisotropic electrical steel are assembled crumbles. This is usually caused by a factory defect. But this happens very rarely.
The most common damage that occurs when repairing a magnetic starter at an armature and a magnetic circuit is corrosion. Switching is carried out by moving the armature down under the action of an electromagnet and up under the action of springs. As a result of the vibration created, rust is flaked off and can accumulate in moving parts.parts that may become stuck over time.
Springs, mounting bolts and cogs
Springs and bolts should be inspected for corrosion. Springs lose their properties over time, which means they must be replaced. A bad spring causes the load to break slowly, which means that the arc created during the separation process will act on the contact groups for a longer time, which will accelerate their wear. It is also impossible to install an excessively strong spring.
This will lead to an incomplete circuit of the magnetic flux, which will cause additional heating of the coil, and this in turn will disable it. Bolts and screws with signs of severe corrosion must be replaced. It is also worth inspecting the threaded connections. Licked, corroded or mechanically damaged threads on bolts must not be used, such bolts must also be replaced.
Magnetic starter coil
When the magnetic starter coil is pulled out of its place, the first thing to do is to inspect its section (the frame on which the copper wire is wound) for cracks and chips. In our case, the copper wire is filled with plastic. If there is damage, then the starter will make a lot of noise during operation. Then you need to pay attention to the coil itself. There should be no traces of heating (blackening) on paper / plastic, and there should be no burning smell. Usually, the main data is indicated on the reels on the side.
This is the number of turns, operating voltage, type of current (ifvariable, then frequency). The brand and thickness of the wire and the brand of the starter for which it is intended are also indicated. It is quite difficult to determine the presence of an interturn circuit. For example, by abnormally low or high resistance. If the coil looks the same as in the photo above, then it can be rewound. If it is filled with plastic, it must be replaced.
Conclusion
In conclusion, we can say that after repairing the magnetic starter, you should try to manually press the anchor. If sticking or slow kickback by the spring is observed, the starter must be reassembled or the spring replaced. Usually, magnetic starters are serviced and repaired according to a plan that was drawn up in advance, depending on the number of on and off per hour. But it is worth noting that the starter should be inspected unscheduled if the equipment that is connected through it is out of order. Usually contact groups also suffer during a short circuit. And sometimes equipment suffers due to damaged contacts.
