Electric engineering

Quality analysis of common problems in motor production process: 1.Problems in no-load 1.1 Negative effects of large no-load current: It reduces the power factor, and secondly, it increases the stator current at full load, causing theator copper loss to increase, efficiency to decrease, and temperature rise to increase; the causes are as follows: (1) The air gap is greater than the design value, increases the air gap magnetic potential and the excitation current; a. The diameter of the rotor is reduced; b. The stator warps, causing the stator diameter increase; c. The bearing housing base is not concentric, causing the motor air gap to be uneven. (2) The opening of the stator core tooth is than the allowable value, which makes the stator core length much greater than the rotor core length, which is equivalent to increasing the effective length of the air gap; The burr of the punched plate and the uneven thickness of the silicon steel plate warpage cause; (3) The stator iron core slot mouth is chiseled too large which increases the stator Kast coefficient and increases the effective length of the air gap; (4) The stator and rotor are not properly aligned, which increases the effective of the air gap; (5) The punched plate burr is large, and the reduction of the iron core when pressing the iron core does not maintain the length or the of the oil pressure machine is insufficient, resulting in insufficient weight of the stator iron core, which reduces the net length of the stator iron core, and reduces the net area the stator tooth and stator yoke, The magnetic density increases, the excitation current increases, and the power factor decreases; (6) Too much use of the stator punched plate, which increases the magnetic density of the stator yoke, increases the excitation current, and reduces the power factor of the motor; (7) rotor is cast for a second or third time, oxidized too much, the burr of the rotor punched plate is too large, the rotor iron core is pressed when reducing the to maintain the length, the pressure is insufficient, so that the weight of the rotor iron core is insufficient, and the magnetic density of the rotor tooth and rotor yoke increases, excitation current increases, and the power factor of the motor decreases; (8) The preheating temperature of the rotor iron core is too high, the time is too long, rotor punched plate is seriously oxidized, the actual iron length is reduced, the magnetic density is increased, the excitation current is increased, and the power factor is reduced; 9) The silicon steel sheet is used as a low brand number sheet, the permeability is low, and the loss is large; (10) The stator winding has few turns, which increases the magnetic density of each part of the magnetic circuit, and the excitation current is large; (11) The stator winding pitch is made, which makes the stator winding a few turns. 1.2 Large no-load loss No-load loss includes iron loss, mechanical loss, and copper loss caused no-load current. The main reasons for large no-load loss are large iron loss or large mechanical loss, which reduces the efficiency and has a negative impact on the temperature. The following are various reasons for the situation: (1) The weight of the stator and rotor iron cores is insufficient, which increases the magnetic density of the tooth andoke, increases the unit loss, and causes the iron loss to increase; (2) Chiseling grooves, generally speaking, chiseling grooves increase the iron by 15%~40%; (3) The slot mouth is chiseled too large, which increases the rotational iron loss and thus increases the iron loss of the; (4) The inner circle is turned and chiseled to short-circuit the stator iron core and increase the iron core eddy current loss; () The stator punched plate has a large burr, and the iron core is short-circuited after pressing, which increases the eddy current loss; (6 The insulation treatment of the stator punched plate is not good or the insulation layer is destroyed, which increases the eddy current loss; (7) The pressure is too high the stator iron core is pressed (greater than 40 kg/cm2), which destroys the insulation layer of the stator punched plate and increases the eddy loss; (8) The quality of the silicon steel sheet is not good or the brand number is low, and the unit iron loss is large; (9) Theator winding has a few turns. All of the above causes result in large iron loss in the no-load loss. The following are the reasons for large mechanical loss: 1) Improper assembly causes the rotor to be inflexible; (2) The bearing is not cleaned