Greetings, I am a newcomer seeking guidance from seasoned professionals in the industry. I have found great assistance in this forum and appreciate the knowledge shared here. As a young individual with limited controls experience in my facility, I encountered an issue with a PowerFlex 40 VFD displaying an "FO4" fault due to undervoltage. After analyzing the problem, I identified that the contactor connected to the safety circuit is causing power loss to the VFD when safety doors are opened briefly. To address this, I consulted with a fellow controls technician and adjusted the auto restart settings to successfully clear the fault without manual intervention. Despite this progress, I encountered a new challenge when attempting to set the restart timer back to 1.0 as advised by another technician. Instead of restarting the VFD, it triggered an "F33" fault related to auto restart failure. I experimented with different timer settings but found success only when the timer was set to 0. I am seeking insights from experienced professionals to help me understand the behavior of the VFD in this situation. Thank you for welcoming me, and I look forward to engaging with and contributing to this community.
To avoid dealing with the hassle of resetting drives after a power blip, we have set the tries to non-zero and the delay to zero as a workaround for ignoring specific faults like undervoltage, overvoltage, and heat sink alarms. This workaround saves time and effort for us. However, in case of a legitimate fault, manual intervention is still required for a reset. Adding a delay time allows the drive to attempt a reset after a fault occurrence. Additionally, for PF70, 750, and 525 drives equipped with a line side contactor, we have implemented a workaround by connecting an auxiliary from the contactor to an input setup for precharge enable. This forces the drive into a precharge state, preventing undervoltage alarms and being gentler on the drive. Unfortunately, this feature is not available on the PF4/40 model.
Many users have found success by setting the parameters to address specific faults like undervoltage, overvoltage, and heat sink alarms. This workaround, which involves adjusting the tries and delay settings, helps prevent the need for manual resets after power interruptions. While "real" faults still require manual intervention, adding a delay time allows the drive to automatically attempt a reset. Additionally, for PF70, 750, and 525 drives with line side contactors, users have implemented a workaround by adding an auxiliary from the contactor to an input setup for precharge enable. This forces the drive into a precharge state, bypassing undervoltage alarms and operating more gently on the drive. Unfortunately, this feature is not available on the PF4/40 model. Thank you for sharing this valuable insight!
To ensure optimal performance, it is recommended that the contactor be positioned on the line side of the VFD as instructed. The issue you are experiencing could be related to the safety circuit cutting off power to the VFD when the doors are opened, causing the VFD to power down. If power is restored before the VFD has completely shut down, it may cause confusion when trying to restart the system. To resolve this issue, it is suggested to implement the following measures: 1. When the safety doors are opened, cut off power to the VFD contactor(s) and activate a time delay timer (TOF) to prevent resetting the safety circuit until the VFD has fully powered down (refer to the manufacturer's recommended time for restart). 2. Conduct a thorough threat assessment to determine if power to the VFD controls can be cut off without affecting the VFD operation. Please note that a safety assessment must be conducted for the second suggestion, as every process is unique. Thank you - James.
Frequent power cycling on the line side of a pf40 can greatly reduce its lifespan. Upgrading to 525s with STO safety features is crucial for avoiding the monthly pf40 replacements caused by this issue. Unfortunately, non-engineer safety personnel sometimes make decisions about line side power removal without fully grasping the consequences, leading to unnecessary equipment failures. This scenario is a common occurrence in industrial settings.
Welcome to the forum! Your problem seems complex but it's great to see you've already got a good grasp on things. For the F33 fault, it's possible your VFD is not seeing a sufficient "off time" before it restarts, since some units need a full cycle of power down before they can reset successfully. When the timer is set to 0, you're essentially providing this full cycle. Try to look into the specs of your particular PowerFlex model to understand the optimal timing for an auto restart, or consider checking if there's a way to program an adequate off period into the safety circuit itself. Keep us updated on how you get along!
Welcome to the forum! It's great to read about your proactive troubleshooting. When dealing with "F33" fault in PowerFlex 40, it's important to understand that it often occurs when your overcurrent control isn't set properly. The VFD suspects it's rushing too much current in during the auto-restart attempt, which triggers this error. I'd steer you to look at your current limits or your ramp-up speed. By slowing down the ramp, you reduce the amount of current being demanded and potentially avoid tripping the fault. If the current limits or ramp-up speeds are set too high, then reducing them might solve your problem. In contrast, if your unit functioned well with the timer set to 0, then it shows that it probably just needs more time to stabilize before it begins operating. Hoping this insight helps you!
Welcome to the forum! It sounds like you're making great strides in troubleshooting with your PowerFlex 40 VFD. The “F33” fault you encountered during the restart timer adjustment could be tied to how the VFD interprets the settings based on its sensing of input voltage and the timing of those signals, especially if there’s any lingering impact from the undervoltage issue. Sometimes, when the timer is configured too long, it can lead to conditions where the drive doesn’t see a stable power source before attempting a restart. I’d recommend checking the voltage levels during those intervals and possibly experimenting with shorter timer settings in small increments to see if that improves stability. Engaging with your control technician friend is a solid approach, so keep collaborating with them for further insights. Best of luck, and don’t hesitate to share what works for you!
Welcome to the forum! It sounds like you're diving deep into some tricky issues with the PowerFlex 40. The "F33" fault can indeed be frustrating, especially when it seems to tie in with the timer settings. It's great that you connected with a technician for guidance! One thing to consider is whether there's a specific parameter set that governs how the VFD interprets the auto restart feature. Sometimes, if the undervoltage fault persists or if the restart attempts are too frequent, the VFD may lock out further retries to protect itself. You might want to double-check not just the timer settings, but also ensure that any input signals, like the control voltage to the contactor, are stable before the restart occurs. Keep experimenting and don’t hesitate to share your findings; many of us have been in a similar spot and can help troubleshoot further!
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Answer: The "FO4" fault is triggered by undervoltage, often caused by power loss to the VFD when safety doors are opened briefly due to the contactor connected to the safety circuit.
Answer: To address the "FO4" fault, one can adjust the auto restart settings to clear the fault without manual intervention, as discussed in the forum.
Answer: The "F33" fault is triggered when there is an auto restart failure. Experimenting with different timer settings might be necessary to find the correct setting, as setting it to 0 may have been a temporary workaround.
Answer: Seeking insights from experienced professionals can help in understanding the behavior of the VFD in situations like the one described, where setting the restart timer can lead to faults like "F33."
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