Hello everyone, I am currently experiencing an issue with a PowerFlex 753 on our site, encountering "input phase loss" errors. This drive has been operating smoothly for over five years, powering a 45kW ND motor for an aluminum cupping press. The fault only occurs during high-speed operation (around 42 amps) after approximately five minutes of running, and has only started happening recently. I have attempted several solutions to troubleshoot the problem, with no success so far: - Adjusting parameter p463 from the default value of 325 to 400 cautiously, to avoid potential drive damage - Swapping out the drive for a new one - Replacing the circuit breaker supplying power to the drive - Ensuring all connections are secure and functioning properly - Confirming that incoming voltages are within acceptable limits, with only a minimal drop of 20mA across all phases of the circuit breaker - Another drive on the same board shows no signs of issues Unfortunately, I do not have access to power monitoring equipment to track incoming power fluctuations. While there is no filter currently installed, the system has operated without problems for years, indicating that this may not be the root cause of the issue. Any assistance or advice on this matter would be greatly appreciated. Thank you.
If you are experiencing power issues, it is possible that your drive is failing. However, consider if any 3-phase equipment has been recently added. It is important to also investigate if there are other factors affecting the incoming power. Have you tried using an upstream reactor to address these issues?
Initially, I suspected that the issue was with the drive failing. However, even after installing a new drive and experiencing the same problem, I am unsure of what the cause could be. Is it common for drives to fail right out of the box? We have another new drive that we could test out. There have been no changes to the switchboard housing the drive for many years. I have not attempted using a reactor yet, but I will need to see if we have a suitable one available on site for testing.
If you do not have power monitoring equipment, what type of voltmeter do you possess? I utilize a Fluke multimeter that can be connected to the incoming phase-phase or phase-ground. By setting the meter to capture min/max readings, you can check for voltage drops after a fault occurrence. Keep in mind that some meters may go into sleep mode, but this feature can usually be disabled for uninterrupted monitoring.
A short while back, I came across a valuable technote from Rockwell that delves into a common issue related to ripple on the DC bus. Essentially, this fault arises from fluctuations in the incoming 3-phase power, which is converted to DC and then rapidly switched to generate AC on the output side. When the rectification process fails to produce smooth DC, DC ripple occurs. In my personal experience, this problem occurred due to a significant variation of more than 2 or 3% between phases. As outlined in the technote, this fluctuation leads to overheating in the capacitors, ultimately reducing the lifespan of the drive and causing it to shut down. While there are other potential causes for this issue, it primarily stems from the input side of the drive. However, the technote also discusses the impact of factors such as a faulty encoder, malfunctioning bearings, and incorrect dynamic brake settings on the DC bus.
When discussing power monitoring equipment, kekrahulik mentioned the importance of having a voltmeter. Personally, I use a Fluke multimeter which allows me to measure voltage levels by connecting it to the incoming phase-phase or phase-ground. By setting the meter to capture min/max values, I can easily track voltage fluctuations during faults. Keep in mind that some meters may go to sleep, but this function can usually be disabled. Although I do own a Fluke multimeter, it does not have the necessary function for power monitoring.
Considering all the steps you've undertaken in troubleshooting the issue, I'd suggest focusing on environmental factors that might have changed recently. These could include temperature and humidity fluctuations or even a newly installed hardware close by generating electromagnetic interference. Also, even though everything seemed fine without a filter for years, the drive’s components could have slowly degraded over time and now require cleaner power. If none of these prove fruitful, the issue could be mechanical - maybe some wear and tear in the motor after five years is causing it to draw more current when running at high speed after it heats up.
It sounds like you have covered most bases, but considering the issue only starts after about 5 minutes of operation at higher amperage, this looks like it might be a thermal issue. An increased temperature in the drive can increase the current draw which might be causing the fault. You might want to check the cooling mechanisms of your drive. Are the fans working correctly? Maybe there is dust or debris buildup that’s reducing the effectiveness of your system's cooling? If your environment is generally hotter now, your cooling may not be sufficient anymore. Also, check the condition of your motor - a failing motor can draw more current than expectations. All the best with your troubleshooting!
It sounds like you’ve done quite a bit of troubleshooting already! Given that this issue has only started recently after years of reliable operation, it might be worth checking for any new loads or changes in the electrical supply that could be affecting the drive, even if they seem unrelated at first glance. Additionally, have you considered inspecting the motor itself? Sometimes, worn bearings or other mechanical issues can cause increased loads that might not raise alarms until you’re pushing the limits. If possible, borrowing or renting some power monitoring equipment could give you valuable insights into any transient issues. Good luck!
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Answer: Answer: Possible causes could include issues with the drive parameters, electrical connections, circuit breaker, or incoming power fluctuations.
Answer: Answer: The user has adjusted drive parameters, replaced the drive, circuit breaker, ensured secure connections, and checked incoming voltages with minimal drop.
Answer: Answer: Consider investing in power monitoring equipment or consult with a professional to diagnose and track incoming power fluctuations.
Answer: Answer: While the absence of a filter is noted, the system has operated without problems for years, suggesting that it may not be the root cause of the issue.
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