Preventing PowerFlex 755 Drives from Losing Speed Reference After Power Cycle

Question:

Hello everyone, I have a concern regarding the PowerFlex 755 Drives losing their speed reference every time the drive is power-cycled. It seems that Parameter 545 resets to default and needs to be set again. I'm wondering if there are any other parameters that need to be adjusted to prevent this issue from happening. Any insights or suggestions would be greatly appreciated. Thank you.

Top Replies

When connected to a Compact Logix or Control Logix PLC, it is possible for the PLC to automatically download a predefined parameter set to the drive upon startup or when a new drive is detected. This process, known as Auto Device Configuration (ADC), allows for seamless integration of new drives as the PLC will program them accordingly. However, a drawback of this technology is that any manual parameter changes made using the keypad will be overwritten upon the next power cycle. To avoid this, it is necessary to adjust the parameters on both the keypad and in the PLC, or solely in the PLC before power cycling. By following these steps, you can ensure the PLC operates with the correct values every time.

Thank you so much

ASF explained that if a drive is connected to a Compact Logix or Control Logix PLC, the PLC may be configured to automatically download a specific parameter set to the drive upon startup or upon detecting a new drive. This feature is known as Auto Device Configuration (ADC). The advantage of this technology is that you can easily replace a drive and have the PLC program it automatically. However, a drawback is that any manual parameter changes made using the keypad will be overwritten the next time the power is cycled. To make a parameter change, you will need to make the adjustment both on the keypad and in the PLC, or only in the PLC and then cycle the power to ensure the correct value is retained.

I've encountered a similar issue with the PowerFlex 755 Drives before. You might want to check Parameter 558, which is the "Stored Speed Select" and ensure it's set to the desired speed. Also, don't forget Parameter 556, the "Startup Speed,". These, along with Parameter 545, should cover the bases for your speed reference. Make sure to save these settings before you power-cycle the software to ensure they're carried over.

Hey there, it seems like you're dealing with quite a hassle there. Here's one thing you should try: consider saving your parameters to non-volatile memory after setting them. It sounds like they are currently stored in volatile memory, which clears when power is lost. The PowerFlex 755 should have a parameter (likely Parameter 11) to save and recall parameter sets to non-volatile memory. Do give this a shot and tell us if it resolves your issue. Happy troubleshooting!

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Frequently Asked Questions (FAQ)

FAQ: 1. Why do PowerFlex 755 Drives lose their speed reference after a power cycle?

Answer: The issue of losing speed reference after a power cycle is often due to Parameter 545 resetting to default settings, necessitating the need to reconfigure it.

FAQ: 2. Are there specific parameters other than Parameter 545 that may need adjustment to prevent this issue?

Answer: While Parameter 545 is a key factor, there may be other parameters related to speed reference or drive settings that could contribute to this problem. It's advisable to review the drive's documentation or consult with the manufacturer for further guidance.

FAQ: 3. How can I prevent PowerFlex 755 Drives from losing speed reference upon power cycling?

Answer: To prevent the loss of speed reference after power cycles, ensure that Parameter 545 is correctly set and consider checking other related parameters for any discrepancies. Regularly saving drive configurations or utilizing backup settings can also help maintain the desired speed reference settings.

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