Hello everyone, I am currently in the process of enhancing a depalletizer for a client by upgrading the hoist. The system is integrated with a SLC500 processor, and the drives are controlled via device net, with the latest addition being the Powerflex 525 installed just yesterday. The Powerflex is controlled using a 2-wire setup. During operation, I have observed that when I raise the hoist while it is empty, it stops precisely as intended, with the frequency decreasing to zero as indicated on the faceplate. However, when I lower the hoist, I notice the frequency fluctuating between 2.0 and 2.5 Hz, causing the hoist to drift downwards until an F007 fault ("Motor Overload") occurs on the drive. The parameters currently set are as follows: - P033: 7.6 - P034: 7.6 - P036: 1768 - P037: 4.03 - P041: 2.0 - P042: 1.0 - P043: 0 - P044: 100 - P045: 0 - P046: 2 - P047: 7 - P048: 2 - P049: 7 - P062: 48 - P063: 49 - P064: 0 - P065: 7 - P066: 7 - P067: 13 - P068: 11 - P411: 12 - P412: 45 - P442: 2.0 - P443: 0.5 It is worth mentioning that I have incorporated a brake resistor and configured it in the parameters for dynamic braking. If anyone has insights or suggestions on what might be causing this issue, I would greatly appreciate your input. I have devoted significant time to troubleshooting this throughout the day but have yet to determine the root cause. Thank you.
Although PowerFlex 525 drives are compact and cost-effective, they may not be the ideal option for a hoist due to their lack of torque proving and high-performance torque control features. Additionally, these drives typically do not come equipped with encoder feedback as standard. Do you have a physical shaft or rail brake installed on the motor or hoist? Is it possible to utilize Stop Mode 8 or 9 for control purposes? While you mentioned that the dynamic braking resistor was set up correctly, I recommend double-checking Parameter A550, specifically the Bus Regulator Enable setting. This is typically enabled by default to prevent unwanted trips during deceleration, but should be disabled when using a braking resistor. Can you confirm whether the braking resistor is actually activating during operation?
In response to Ken Roach, it is noted that while PowerFlex 525 drives are compact and cost-effective, they may not be the ideal choice for hoists due to lacking torque proving and high-performance torque control features, as well as the absence of standard encoder feedback. For those with a physical shaft or rail brake on the motor or hoist, it is recommended to utilize Stop Mode 8 or 9 for control. Additionally, it is advised to check Parameter A550, Bus Regulator Enable, which should be disabled to allow proper use of a braking resistor without causing nuisance trips during deceleration. Ensuring that the braking resistor is effectively engaged is crucial in such cases. How can one verify if the brake resistor is properly functioning on a physical shaft?
If you're utilizing an encoder and configuring the drive for flux vector control, you may encounter difficulties when attempting to control a hoist using 525 in sensorless vector control, particularly at zero speed.
Kekrahulik inquired about the use of an encoder and setting up the drive in flux vector control for a hoist operation. He cautioned that attempting to control a hoist with 525 in sensorless vector control may result in issues at zero speed. Despite not using an encoder, the Powerflex40 has been operational for years. How can I properly configure the drive for Flux vector control?
When it comes to drive parameters, option 1 is sensorless (SVC) and option 3 is vector control. While attempting vector control without an encoder is possible, it is somewhat ineffective. In sensorless operation, the drive calculates the motor position based on voltage and current. This can be easily performed during operation but becomes more challenging when the motor is still. It is important to understand that in order to hold a load in place, the drive must generate a certain frequency to counteract the downward force of the load. If the drive outputted 0 hertz, the load would simply fall. Using a drive specifically designed for hoists is the most effective choice in this scenario. The next best option would be to utilize an encoder and vector control. Lastly, autotuning or manually tuning the drive may be considered, although this option is not preferred. It is crucial to prioritize safety, especially if there is a risk of individuals being in harm's way. Opting for a drive designed for hoists is the most reliable solution in such situations.
Hi there, It sounds like you've done a comprehensive job troubleshooting this issue. Considering your circumstances, it might be worth checking that there is no overload in the actual motor causing these faults. I also note the fluctuation of frequency when lowering the hoist; have you checked for a possible back EMF (electromotive force) irregularity causing the inconsistencies? You could also consider adjusting your stop ramp time (P043) and braking level (P047) parameters for more gradual decline. This might help mitigate any motor overload during the lowering phase.
It appears you have a comprehensive setup and have examined the parameters thoughtfully. In your situation, the fluctuation causing the hoist to drift could potentially be due to an issue with the load regulation. The parameter P041 is set to 2.0 which is too low. Try increasing this for better regulation of the load, especially when lowering. You should also ensure that the brake resistor is functioning correctly and can handle the energy dumped during lowering operation. Lastly, double check your motor tuning parameters (P033, P034), they should correspond to the motor's nameplate details accurately. Those little tweaks might help sort out this issue. Good luck!
Based on your detailed description, it sounds like this could be a regenerative problem or an issue with brake resistor sizing. If the hoist is loaded, it may generate energy while lowering which needs to be handled by the braking resistor. If it can't handle it, the drive could be faulting. Are you able to verify if your brake resistor is sized correctly? Furthermore, you could also adjust parameters P044 and P045 to manipulate the load handling capacity; this might help in terms of voltage tripping or to stabilize the downward drift you're noticing. If all else fails, you might want to consider using another method like a 4-wire setup for better control, even though it's a little more complex than a 2-wire scheme. Good luck with the troubleshooting!
Hey there, Given your description, the issue seems to be related to frequency regulation when the load on the hoist is reduced. I would recommend checking how your system manages regenerative energy. In the PowerFlex 525, there are two ways to manage regenerative energy that overloads the bus: use a dynamic brake or feed the energy back into the line (you need an Active Front End for that). If you have already set up a dynamic brake, make sure that dynamic braking is functioning as expected. Check your dynamic brake resistance value and duty cycle parameters. If these values do not match your brake resistor, it might cause issues. The F007 fault can also be caused by the motor drawing more current than the drive's rated current. This could be a sign of motor mechanical issues (like wear), motor insulation issues or perhaps any mechanical load jamming. It may not directly relate to your frequency drift issue, but it's worth checking out. Also, remember that changes in P041 and P042 may affect your Stop and Start routine. You may want to experiment with these values a bit, just remember to note down your initial settings so you can always revert back. Finally, ensure that the Powerflex 525 software version is compatible with your SLC500 processor. I hope this helps! Good luck with your troubleshooting!
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Answer: Answer: The frequency fluctuation and hoist drifting issue when lowering the hoist could be caused by a fault such as "Motor Overload" (F007) on the drive. This may be due to incorrect parameter settings, improper configuration of the brake resistor, or other factors affecting the control of the hoist.
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