Motor Diagnostics (2)

2. Electric Motor

The primary purpose of the electric motor is to convert electrical energy to mechanical torque. As a result, it has both electrical and mechanical components that must be considered.

Electric motors include mechanical and electrical components.

The first review is mechanical.
The primary mechanical problems include:

• Bearings
• Bad or worn shaft or bearing housings
• Vibration issues

Each of these can be detected using:

• Motor current signature analysis will detect the more severe problems.
• Vibration analysis will detect the faults earliest but requires a fair amount of experience.
• Infrared will detect problems when they are severe.
• Ultrasonics will detect the more severe problems

Electrical faults include:

• Winding shorts including turn to turn and coil to coil
• Insulation to ground faults
• Winding contamination
• Rotor faults including casting voids and broken rotor bars
• Air gap faults including an eccentric rotor

The winding tests to detect these problems include:

• MCA and MCSA will detect all of the faults
• Vibration will detect late-stage faults
• Insulation to ground will only detect ground faults
• Surge testing will only detect winding shorts in the first few turns of the winding
• All other testing will only detect late stage faults.

to be continued.....

Is this articel useful? Please help us with click our sponsors.