Learn about commutator repair

(1) Short circuit between commutator segments
The so-called short circuit between the commutator segments means that there is a short circuit connection between two adjacent commutator segments on the commutator. Short circuit between commutator segments. Large sparks will appear on the surface of the commutator; when the short circuit is serious, ring fire will occur on the surface of the commutator.

The repair of the short circuit between the commutator segments is as follows:
①Cleaning with slot cleaning sheet When the armature winding is burnt due to short-circuit fault, the fault point can be found by observation method. In order to determine whether the short-circuit fault occurs inside the winding or between the commutator segments, the winding wire head connected to the commutator segment should be disconnected, and then use a check light to check whether there is a short circuit between the commutator segments, such as on the surface of the commutator segment. If a short circuit is found, or the spark burns the scar, usually use the slot cleaning sheet shown in Figure 227 to scrape off the short-circuited metal chips, brush powder, corrosive substances, etc., until the check light is used to check that there is no short-circuit. And use mica powder and shellac or mica powder, epoxy resin and polyamide resin (650) to mix into a paste, then fill in the grooves and let it harden and dry.
②Clean the V-groove and V-ring of the commutator block If the short circuit between the chips cannot be eliminated after carefully removing the external debris between the chips. At this time, the commutator must be disassembled, and the V-groove and V-ring of the commutator group must be carefully cleaned. Before disassembling the commutator, wrap a layer of elastic paper with a thickness of 0.5 to 1 mm on the outer circumference of the commutator for insulation, and mark the fault location, and then cover the stacking die, and then Take the commutator apart. Further check the faults between the commutator segments, the surface of the V-groove and the V-ring, and deal with them according to different faults.
③ Replacement of mica sheets between sheets If the short circuit between sheets cannot be eliminated by the above method, only the mica sheets can be replaced. The method of replacing the inter-chip mica flakes is as follows.
Put the above disassembled commutator segment on the flat plate, mark the faulty commutator segments, and then fasten it with a rubber ring, then remove the steel wire hoop or weft-free glass wire, and use a sharpened A section of the wide saw blade is inserted between the faulty pieces, after loosening, the faulty commutator piece is pulled out, and a new commutator piece of the same specification as the faulty commutator piece is inserted.
After the commutator plate is replaced, use iron hoops (with thick cardboard inside) to fasten the commutator plate group. Heat the commutator block to 165℃±5℃, tighten the screws for the first time, and use the calibration lamp to check whether the short circuit between the blocks has been eliminated after cooling. If it is not eliminated, you should carefully find the cause of the failure or repeat the above work; if the short circuit between the chips has been eliminated, perform assembly.