13 Common Questions About Motor Maintenance and Troubleshooting

Motor maintenance and troubleshooting are crucial for ensuring the efficiency and longevity of electric motors. Understanding common issues can help prevent damage and improve operational performance. Here, we address 13 frequently asked questions related to motor maintenance and provide valuable insights to keep your systems running smoothly.

Shaft currents occur in the motor’s shaft, bearing housing, and base circuit. These currents can be caused by:

• Magnetic Field Asymmetry
• Harmonics in the Power Supply
• Eccentric Rotors Leading to Uneven Air Gaps
• Gaps Between Halves of the Removable Stator Core
• Improper Stator Core Lamination

Consequences:

Shaft currents can erode bearing surfaces, leading to pitting and increased friction, heat generation, and eventually, bearing failure.

Prevention:

• Eliminate magnetic flux pulsations and harmonics (e.g., by adding AC reactors on the inverter’s output side).
• Insulate bearing housings and bases for sliding bearings, and provide insulation for the outer rings of rolling bearings.

For more on motor maintenance, visit Baldor’s Motor Solutions.

Altitude affects motor performance in the following ways:

• Increased Temperature Rise: Higher altitudes lead to higher temperature rises, reducing the motor’s power output.
• Voltage Breakdown (Corona Effect): High-voltage motors require protection against electrical corona.
• DC Motor Commutation: At higher altitudes, DC motor commutation is less effective due to reduced air density, which affects brush material performance.

Operating a motor under light load results in:

• Low Power Factor
• Reduced Efficiency

This leads to wasted energy and inefficient operation. It’s best to operate motors at their optimal load capacity for cost-effective performance.

Overheating can result from:

• Overload Conditions
• Phase Loss
• Clogged Cooling Vents
• Excessive Low-Speed Operation
• High Harmonics in the Power Supply

Before restarting a motor that has been idle for an extended period:

• Check Insulation Resistance: Ensure it meets the required standards.
• Clean the Motor: Remove dust and debris.
• Replace Bearing Lubricant: Ensure bearings are adequately lubricated.

For insulation resistance standards, visit Baldor Motor Care.

In cold conditions, motors can experience:

• Insulation Cracking
• Frozen Bearing Lubricant
• Solder Joint Degradation

To prevent this, motors should be pre-heated and inspected before operation.

Three-phase current imbalance can be caused by:

• Uneven Supply Voltage
• Poor Internal Connections
• Short Circuits in the Motor Windings
• Incorrect Wiring

When a motor designed for 60Hz operates on a 50Hz supply, it causes:

• Increased Magnetic Flux
• Higher Excitation Current
• Overheating Due to Increased Copper Loss

This can lead to motor failure if not managed properly.

Phase loss can occur due to:

• Poor Switch Contacts
• Faulty Transformers or Broken Wires
• Blown Fuses

On the motor side, phase loss could be caused by:

• Loose Wiring Connections
• Internal Wiring Faults
• Broken Motor Windings

Mechanical issues such as:

• Poor Bearing Lubrication
• Loose Fastening Screws
• Foreign Objects Inside the Motor

Electromagnetic issues like:

• Overload Operation
• Phase Imbalance
• Short Circuits in the Stator or Rotor

Before starting a motor, make sure to:

• Check Insulation Resistance
• Verify Power Supply Voltage
• Ensure Proper Motor Wiring
• Inspect Start-Up Equipment
• Check Grounding and Zeroing Connections

Motor bearing overheating can result from:

• Tight Bearing Fits
• Improper Part Alignment
• Inadequate Lubrication
• Shaft Currents

Low insulation resistance may be due to:

• Moisture in Windings
• Accumulation of Dust or Oil
• Aging of Insulation
• Damaged Wiring or Insulation Layers

By understanding and addressing these 13 common motor issues, you can ensure smoother operation and prolonged motor life. For more tips and solutions on motor maintenance, visit Baldor Air Compressors.