tailieunhanh - Industrial Machinery Repair Episode 2 Part 13

Tham khảo tài liệu 'industrial machinery repair episode 2 part 13', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 534 Maintenance Welding different voltages it may save time to place lugs on the ends of all the stator leads. This eliminates the necessity for loosening and resoldering to make connections since the lugs may be safely joined with a screw nut and lock washer. Exciter Generator If the machine has a separate exciter generator its armature coils brushes and brush holders will need the same general care recommended for the welder set. Keep the covers over the exciter armature since the commutator can be damaged easily. Controls Inspect the controls frequently to ensure that the ground and electrode cables are connected tightly to the output terminals. Loose connections cause arcing that destroys the insulation around the terminals and burns them. Do not bump or hit the control handles it damages the controls resulting in poor electrical contacts. If the handles are tight or jammed inspect them for the cause. Check the contact fingers of the magnetic starting switch regularly. Keep the fingers free from deep pits or other defects that will interfere with a smooth sliding contact. Copper fingers may be filed lightly. All fingers should make contact simultaneously. Keep the switch clean and free from dust. Blow out the entire control box with low-pressure compressed air. Connections of the leads from the motor stator to the switch must be tight. Keep the lugs in a vertical position. The line voltage is high enough to jump between the lugs on the stator leads if they are allowed to become loose and cocked to one side or the other. Keep the cover on the control box at all times. Condensers Condensers may be placed in an AC welder to raise the power factor. When condensers fail it is not readily apparent from the appearance of the condenser. Consequently to check a condenser one should see if the input current reading corresponds to the nameplate amperes at the rated input voltage and with the welder drawing the rated output load current. If the reading is 10 to 20 more at