Electrical Maintenance - DC Motor Maintenance скачать в хорошем качестве

Electrical Maintenance - DC Motor Maintenance

You know that electric motors can be divided in two main classes: AC and DC. This training film uncovers basic knowledge of direct current (DC) electric motors: how they work, main principles, functions, physical processes, construction, as well as preventive maintenance and troubleshooting. To understand what makes the electric motor turned, we will go through electromagnetic induction and current-carrying conductors. It will be useful for students, who just started learning electrical machines, and for experience electricians, who wasn't working with electric motors, to refresh their knowledge. _________________________________ Timeline: Segment 1 00:35 PRINCIPLES OF OPERATION AND PARTS IDENTIFICATION 02:04 Motor Action 02:16 An Elementary Motor 02:22 Why Motor turns 02:35 Main Magnetic Field and Conductor 03:00 Commutator Segments and Brushes 03:35 How Motor turns 03:40 Magnetic Field and Magnetic Flux 04:15 Armature, Shift and Armature Reaction 04:31 Position of Neutral Plane 05:07 Sparking 05:46 Small Poles 06:44 Construction of Electric Motor 07:29 EMF and CEMF 07:59 Voltage Supply. Electromotive Force Induction 08:05 How Counter Electromotive Force are produced. Explanation 08:50 Parts of Typical Compound DC Motor 09:00 Frame 09:20 Field Pole Pieces 09:47 Shunt Field and Series Filed Coils 09:55 Interpole Coil 10:08 End Bells 10:24 Brush Rigging and Holders 10:38 Brush Tensioning Device 10:43 Brush Pigtail 10:54 Armature Shaft, Armature Core, Armature Windings and Commutator Segment 2 11:45 IDENTIFICATION AND CLASSIFICATION 12:41 Illustration of Series Motor 12:59 Simple Schematic Diagram 13:36 Overspeed 13:49 Resistance and Current Flow 14:23 Shunt Motor 15:18 Compound Motor 15:44 Importance of Marking 16:00 Manual and Diagram 16:40 Nameplate 16:56 Motor Leads Marking Segment 3 17:45 BRUSHES AND BRUSH RIGGING MAINTENANCE 18:31 Before you start 18:58 Common Source of Trouble 19:50 Sparking, Arcing and Heating 20:12 Commutator Problems 20:34 Cleaning the Motor is the first order in any Maintenance Procedure 20:49 Commutator Check 21:32 How Good Brush Looks 22:18 Brush Holders Check 22:38 Adjustment of Brush Holders 23:28 Maintenance and Repair Parts Manual 23:34 Preferable Distance from the Surface 23:50 Stagger of Rigging Adjustment 24:30 Sign of Wear 24:56 Brush Replacement 25:10 All New Brushes must be seated 26:57 Pressure Setting for Tension Devices 27:17 Brush Tensioning Scale Segment 4 28:00 COMMUTATOR MAINTENANCE 28:38 How to reduce electric motor problems 28:47 Good-looking commutator 29:09 What to use to clean any commutator 30:07 Bearing end of the commutator and the area behind the risers for carbon dust and dirt 30:52 Threading and grooving 31:22 Low brush pressure, contamination or the wrong type of brush 31:58 About grooving in details 32:38 Damage commutator. Copper drag 33:01 What causes copper drag? 33:46 What is flashover and what causes it? 35:18 Extreme overload and sparking or arcing 36:09 Result of flashover 36:21 If you do or not do your job well 36:59 Preventive maintenance performed periodically and thoroughly will prevent flashover 37:11 Dirt and other type of contamination on electrical equipment Segment 5 37:39 TROUBLESHOOTING 38:15 Identifying the problem 38:23 What you need to know about the motor to look for a ground 38:41 Insulation test for grounded motor 39:07 Locate the grounded parts 39:36 Where the ground can be happened 39:45 If raise the brushes off the armature 39:57 Series field check 40:13 Shunt filed check 40:28 Armature field might be grounded too. Check it! 40:56 Continue elimination process 41:24 Determining which coil is damaged 42:06 Check the circuits 43:51 If no readings 44:11 Difference in the readings 44:37 No reading on brush due to holder tension 45:54 Check the readings on the brushes after tension adjustments 46:05 When all brushes on the armature 46:44 A short circuit problem 47:56 If a fuse doesn't blow or the breaker doesn't trip the short will quickly become an open 48:09 Observation first Segment 6 48:48 DISASSEMBLY AND ASSEMBLY 49:35 First remove the brushes and field coil leads from the brush rigging 49:54 Then mark the end bells and remove them 50:32 Now armature can be removed 50:50 Bearing removal technique 50:59 Inspection of commutator 51:31 Armature winding inspection 51:56 Armature banding check 52:04 Pay attention to condition of the insulation 52:08 Cleaning 52:26 Growler 53:26 Field poles and coils checking 54:15 Remove dust and dirt 54:26 Megatest 54:53 End bells checking and cleaning 55:00 Brush rigging and holders cleaning and inspection 55:38 Motor reassembling 57:47 Turn the shaft by hand. It should and must move freely 58:00 Bad bearing 58:28 Condition of brushes 58:48 Set the tensioning device 58:57 Take a ground reading on it and check it for opens 59:11 Summary _________________________________ Produced by NUS Corporation A Halliburton Company 1980 #electrical #maintenance & #troubleshooting