What do a broken razor, car and washing machine have in common? Let’s get you there quickly: they all have a bad motor. So why would your razor, car and washing machines break down in the first place? This article has some answers for your question.
Problem 1: unable to start
Possible reasons:
- No voltage for motor power supply
- Motor power cord disconnected or joint loosening
- Armature winding open
- Poor contact between the brush and the commutator
- Motor power switch damaged or poor contact
- The armature is stuck
Problem 2: slow speed
Possible reasons:
- Brush winding grounding
- Armature winding has short circuit elements
- Severely worn-out brush causes poor contact between the brush and commutator as well as small pressure of the brush spring
- Bearing wear or lack lubricating oil
- Low power supply voltage, or use the dry battery for too long a time
Problem 3: too fast speed
Possible reasons:
- Too high power supply voltage
- Weakened stator magnetic field
- Too light motor load
Problem 4: electriferous case
Possible reasons:
- Armature winding grounding
- The stator excitation winding grounding
- The commutator grounding
- The brush rod grounding
- The brush holder of the commutation device grounding
Problem 5: brush throwing excessive sparks
Possible reasons:
- The brush is not located on the neutral line
- Too small a contact surface between brush and commutator, and too high current density
- Short circuit between commutators
- Severely uneven commutator surface
- Uneven mica between the commutators
- Impure brush material, with hard crumbs or other impurities
- Brush holder grounding
- Brush winding grounding
- Short circuit of brush winding
- Reverse connection of brush winding
Problem 6: the commutator produces sparks
Possible reasons:
- The brush is far away from the neutral line
- The commutator is seriously uneven, which makes poor contact between the brush and the commutator
- Excessive potential difference between commutator
- Serious break or short circuit of armature winding
- Armature winding grounding
- Too high voltage or rotating speed of motor
Problem 7: fail to start every time
Possible reasons:
- The armature winding has circuit breaking units
- Poor contact of the power switch
- Too large commutator ovality and too short brushes
Problem 8: crash sound when running
Possible reasons:
- Bending of motor rotor
- The armature slot wedge protruding
- The armature winding end touches the casing
- The bearing is damaged, causing the armature broom
Problem 9: the armature hisses loudly
Possible reasons:
- Too hard brush
- Too high pressure of brush springs
Problem 10: fuse burnt when loaded
Possible reasons:
- Over-voltage of motor power supply
- Brush is not located on neutral line
- Short circuit of armature winding or excitation winding
Problem 11: fuse burnt when no-load
Possible reasons:
- The armature winding is severely broken
- The armature winding severely grounding
- The brush holder grounding
- The motor bearing is too tight
- The excitation winding is severely shorted
- The brush away from the neutral position
Problem 12: the brush rattles
Possible reasons:
- Uneven mica between the commutators
- Uneven commutator piece
- Wrong brush size specifications
- Large bearing clearance
Problem 13: casing heated
Possible reasons:
- No good heat dissipation and the armature winding is damped severely
- Long-term overload operation
- Bad lubrication of bearings
Problem 14: armature winding fever
Possible reasons:
- Serious dampness of armature winding
- Serious motor overload
- Short circuit unit of armature winding
Have you experienced other problems about DC motor? Feel free to contact us or leave a comment. We’d be glad to hear from you and help you.
