The insulation sleeve of the motor accessories is intact without cracks or looseness. The lead connection should be firm, and the insulation resistance value should not be lower than 0.5M Ω at a working temperature of 75 ℃. In terms of the electric brush device, it is required that the lower edge of the brush box be 2-4mm away from the surface of the motor accessories. If the distance is too large, it will cause the electric brush to jump inside the brush box. If it is a hard electric brush, it is likely to break. The electric brush should slide flexibly inside the brush box, and the surface of the inner hole of the brush box should be smooth. The radial dimension tolerance of the inner hole of the brush box is H10, and the axial dimension tolerance is H8. The tolerance for the width and thickness dimensions of the electric brush is d11. The gap between the electric brush and the brush box wall should be between 0.1~0.2mm. If the gap is too large, the electric brush will produce tangential oscillation inside the brush box, which will affect the normal operation of the motor components; The gap is too small, causing the electric card to be stuck in the brush box, resulting in arc light similar to welding burning the surface of the copper ring
During maintenance, it is necessary to conduct a detailed inspection of the motor components: whether the working surface of the motor components is smooth, and whether there are defects such as burn marks and streaks. The working surface should be smooth and free from rust and oil stains. The external insulation binding of motor accessories should be correct and well sealed. If not handled properly, non-woven glass ribbon impregnated with synthetic resin can be used for binding to prevent mica flakes from scattering during motor operation. The coordination between motor accessories and shafts, as well as the coordination between each ring and insulation sleeve, should be firm. When tapping the copper ring and sleeve copper coordination with a small hammer, there should be a metallic sound
The contact between the electric brush and the ring should be tight. The pressure difference between each brush should not exceed 20% of its average value. A wound rotor asynchronous motor with a brush lifting device ensures that the electric shock on the short-circuit ring contacts uniformly with the blades on the motor accessories, with a contact area of over 60%, to avoid single-phase operation of the rotor or loss of elasticity due to overheating of the contacts. For minor burn marks, pockmarks, brush marks and other defects on the surface of motor accessories, they can be polished with oilstone and fine file, and finally polished with zero grit sandpaper. In general, motor components should not be easily turned, as turning them once can significantly reduce their lifespan