Hello everyone! I am currently dealing with a 50 HP 460/600V motor connected to a PF525 drive. After confirming that the motor is wired correctly, I noticed that the service factor is 1.15 and the power factor (pf) is 0.8. The nameplate specifies that for 460V, the motor should be wired in a delta configuration, with a full load amperage (FLA) of around 52A. There seems to be an issue when running the motor at 80 Hz, as it triggers an overcurrent condition with unstable current fluctuations. By running it at 80% capacity, the current stabilizes at about 50A, which aligns with expectations. However, I have detected a burning smell from the windings when the junction box is opened. I have conducted insulation resistance testing on the motor and wiring, which appear to be in good condition. Despite having the equipment tuned, I have requested the motor sizing calculations for a thorough review, although it may not be provided. It is possible that the motor is undersized, given that it operates at its FLA at 60 Hz. Although no overcurrent or overload faults appear in the fault logs, there is speculation about the motor being faulty. Nevertheless, I am considering the possibility of a malfunctioning drive or potential misfiring causing the issues. I am uncertain about how to investigate this further. The drive is supplied with shielded Variable Frequency Drive (VFD) cable, with the shield wires securely grounded before connecting to the drive. Notably, there is no line reactor or output choke present in the setup. I believe there are potential solutions to explore, but I am unsure about the next steps to take at this juncture.
The PF525 drive has a maximum capacity of 30 horsepower.
According to padees, the PF525 drive is limited to a 30HP capacity. This suggests that the drive is most likely a 30HP model. I noticed this while working a 14-hour shift last night.
Would you be able to upload a picture of the motor nameplate for identification purposes? This would greatly assist in determining the necessary information about the motor.
A 52 amp current draw may indicate a motor with a power output similar to that of a 40HP motor. For instance, a 30HP PF525 motor is typically rated at 43 amps, but the actual amperage can vary depending on the motor type and the workload it is handling. A similar scenario occurred with a small extruder powered by a 22kW A-B motor, where the high workload necessitated the use of a 40HP PF755 motor, which has performed reliably for the past 6 years. The next step is to upgrade the controls and replace the outdated Dnet and SLC500 components with a more modern setup, including a proper E-Stop system for improved safety measures. LOL.
User Bering_C_Sparky requested a photo of the motor nameplate, so I will be posting that soon. I recently completed a retrofit from a soft start to a drive, feeling a bit overwhelmed by the process. The drive is actually a 700 series, and I will share information from both the soft start and drive shortly.
You've certainly covered a lot of ground with your troubleshooting—and it seems like you have a handle on things! Given the info you've provided, one thing that sticks out to me is the absence of a line reactor or output choke in the setup. Adding one helps filter out voltage spikes and electrical noise, which could potentially assist in stabilizing your current fluctuations. Also, when the motor is running at higher frequencies, the internal resistance of the windings could cause the motor to heat up more than usual. This might explain the burning smell you're picking up on. Lastly, it might be worth considering the quality and length of your shield wires. A poorly grounded shield could impact the performance of your motor and drive. Hopefully, these suggestions will help you find a solution. Good luck!
Given the symptoms you've described, it sounds like you have multiple factors at play. A burning smell from the motors usually indicates overheating, which could be due to overloading or some insulation failure. You've confirmed that it's not fully loaded, hence, insulation degradation could be a likely bet, even if the insulation resistance test comes out okay. Insulation might fare well in tests at room temp, but fail under operating temperatures, as the heat could exacerbate the breakdown. As for the drive, although no overcurrent or overload faults appear, intermittent misfires could still be at play. A fluke or oscilloscope can help trace this issue. Finally, the lack of a line reactor could be contributing to the issue. Line reactors can help mitigate harmonics, improve power factor, and protect VFDs from voltage spikes. Without one, your drive and motor may be more susceptible to power line disturbances. Consider installing one. Remember this is speculation based on your brief. It is advised to consult with an experienced electrical engineer or technician in person.
Hi there, it sounds like you've covered a lot of ground already. The burning might indicate a short or that the motor windings are degrading which would result in loss in insulation resistance over time - even though it tests okay now. One possible problem could be harmonics from the VFD, as this can cause motors to run hot and may lead to overcurrent situations at higher frequencies. Given that there's no line reactor or output choke, I'd look into their absence, as these components can help mitigate harmful effects of harmonics. Alternatively, you could also check the drive output for any misfire as you suggested, or consider if there could potentially be an issue with the VFD setup itself. Remember, safety comes first; keep the drive powered down if it's producing a smell or there's any suspicion of a problem.
Based on your observations, it sounds like you're dealing with an issue that's not straightforward. One potential issue could be the absence of a line reactor or an output choke; both help in reducing the harmonic distortion, which might be causing the unstable current fluctuations at higher Hz. Also, the burning smell is quite concerning and could suggest overheating due to a possible misalignment or bearing issue. Lastly, it may be worth it to double-check the programming of the drive to ensure it syncs with the motor's operations. Just in case it's not already been considered, see if you can verify whether the VFD is programmed to handle the specific motor type, and has the correct parameters for voltage, current, and speed range set. This issue could very well be more about handling the system at a system level rather than a component level. I hope this helps, and good luck finding a solution!
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Answer: - The issue could be due to motor sizing, drive malfunction, or potential misfiring causing the problem. Further investigation may be needed to pinpoint the exact cause.
Answer: - The burning smell could indicate overheating due to high current consumption, which may be caused by factors such as motor undersizing, drive issues, or improper configuration.
Answer: - The lack of a line reactor or output choke could contribute to current fluctuations and instability. Considering adding these components to help mitigate the issues.
Answer: - Steps to consider include verifying motor sizing, checking for drive malfunctions, inspecting connections and grounding, and exploring the possibility of misfiring during operation. Consulting with a professional may also be beneficial.
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