Mike Dolt Enterprises
Mike Dolt Enterprises
User: S'mise, Location: Michigan
Asked on: Saturday, May 29, 2021 at 9:53 am EDT
Answered on: Thursday, June 20, 2024 at 11:06 am EDT
Question: I've got a machine with an Allan Bradley AC 3p servo motor VPL-B1002 that runs well but occasionally overheats for no reason.I have seen it heat up to 100c while in standby.Looking at the kenetix 5700 drive motor diagnostics screen, it shows 0 amp motor current but a motor utilization of 28%.Line, Bus and control voltage are fine.How the heck can a motor overheat while drawing no current?If I wait a few minutes, the utilization drops to <1% and the temperature drops to normal all on its own.As I say, this is without the motor running.Any idea what's going on?
Possible Causes
False Motor Current Reading
The drive may be incorrectly reporting 0 amps, even though the motor is drawing current. Check the current reading using an external ammeter or oscilloscope.
Unbalanced Magnetic Flux
Misaligned or damaged magnetic components within the motor can create unbalanced flux, resulting in overheating.
Electrical Noise
Electromagnetic interference (EMI) from other devices or electrical noise on the motor supply can cause the motor to overheat.
Bearing Failure
Excessive wear or misalignment of bearings can increase friction and generate heat.
Coolant Failure
If the motor is water-cooled, a problem with the coolant supply or temperature regulation can lead to overheating.
Software Glitch
A software issue within the drive or the machine controller may be causing the motor to run at an unexpected speed or draw excessive current, even in standby mode.
Troubleshooting Steps
Verify Motor Current Reading
Connect an external ammeter in series with the motor to verify the current draw.
Inspect Magnetic Components
Remove the motor and inspect the stator and rotor for any damage or misalignment.
Check for Electrical Noise
Use an oscilloscope or other diagnostic tool to detect any EMI or electrical noise on the motor supply.
Examine Bearings
Listen for unusual noise or vibration when the motor is running. Check for excessive backlash or play in the bearings.
Review Coolant System
Ensure that the coolant is flowing properly and at the correct temperature.
Update Software
Check for any available firmware or software updates for the drive or machine controller.
Additional Considerations
Environmental Factors
High ambient temperature or humidity can contribute to motor overheating.
Motor Duty Cycle
Excessive or improper motor loading can lead to overheating.*
Overvoltage or Undervoltage: Deviations from the rated voltage supply can affect motor performance and cause overheating. Flag for review