Can a commutator be repaired?

Mold-type commutators are not repairable and must be replaced if damaged. When a commutator comes in for a repair, units are disassembled and rebuilt with new copper and mica segments using the same quality assurance processes applied to new commutators.

What does a commutator do in a DC motor?

Commutator and Brushes The commutator on the DC generator converts the AC into pulsating DC. The commutator assures that the current from the generator always flows in one direction.

What are the major problems encountered in a DC machine?

4 Major Troubles in a DC Motor with Reasons

• Failure to start.
• Sparking at brushes.
• Vibrations and pounding noises.
• Overheating of DC Motor.

How do I know if my DC motor is bad?

If the meter still reads as an open circuit after the shaft has been rotated, the conducting brushes may be bad.

1. Touch the leads of the meter to the two motor leads.
2. This type of ohm reading will indicate that the motor is good and the problem resides with the electrical circuit itself and not the DC motor.

Why are brushes used in DC motor?

A carbon brush is a sliding contact used to transmit electrical current from a static to a rotating part in a motor or generator, and, as regards DC machines, ensuring a spark-free commutation.

How does a DC commutator work?

Commutators are used in direct current (DC) machines: dynamos (DC generators) and many DC motors as well as universal motors. In a motor the commutator applies electric current to the windings. By reversing the current direction in the rotating windings each half turn, a steady rotating force (torque) is produced.

What causes a DC motor to fail?

A winding failure—which is often caused by a breakdown of the winding’s insulation—will cause a short in the motor. Common causes of winding failure include high temperature, too many starts, contamination, too much current, excessive voltage and physical damage.

Can a DC motor be repaired?

DC Motor Repair Time Let’s face it, there is a lot that can go wrong with a DC motor, but most of it involves fairly straightforward repairs, such as bearing replacement or a simple brush replacement. These repairs won’t take as long as a more complicated repair like an armature or field coil rewind.

Is it economical to repair a DC motor commutator?

On large industrial machines, from several kilowatts to thousands of kilowatts in rating, it is economical to replace individual damaged segments. Replacing the copper and mica segments is commonly referred to as “refilling”.

What are the common problems with DC motors?

DC Motors: Common Problems and Maintenance of Brushes. 1 Brush surface is smooth and shiny. 2 Brush surface is not chipped or cracked. 3 Brush shape conforms to commutator shape. 4 The brush is not too short (or worn down) 5 Brush pigtail is in good condition. 6 Brush pigtail is securely fastened to the brush.

Why is my DC motor out of round?

If the eccentricity of the commutator is not acceptable, you could end up with broken brushes and/or brush springs. A commutator that is out of round can also lead to potential high bars, which can damage the brushes and cause excessive arcing where the brush contacts the copper bars.

How can I check the armature of my commutator?

However, if the motor design has external brush holders, you can unscrew the brush caps and remove the brushes. Depending upon brush size, this may allow access to the commutator without removing the armature from the motor. The first check to see if your armature windings are shorted is the “180° Resistance” test.