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bodine

Regenerative fault.

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I got a couple of Allen Bradley Power Flex 40 drive that give me a F05 (Over Voltage) fault. These drive operat two 5 hp sump pumps.. I'm think that that sometime the check balls in the lines don't seal good and the pumps are spinning from a liittle back flow from the head pressure when they try to start causing this... I have the drives set for Flying start and to try to restart 3 times before faulting... but it doesn't seem to hlp with the issue.. Any other suggestions????

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Sounds like an application issue. If the motor is being pushed while still energized it will generate electricity. This will raise the DC bus voltage and cause the drive to trip to protect itself. I only know of two solutions: - Get rid of the regenerative condition (fix the check valve) - add DC Bus regenerative braking (ie. resistor bank) Or replace the drive with a regenerative drive

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I've suggested changing the check balls, but where I work everything is an elctrical problem, never mechanical. If you know what I mean?... It's got wire going to it must be an electrical problem.. I have already put a new drive int the cabinet and it still faults.. They are still not convienced.... That the problem is leaky check valves..... I was just looking to see if someone had suggestions that I have not tried yet... Thanks..

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Does this fault occur only when you stop the motor, or when it is commanded to run? Does it ever happen when the motor is sitting still? Can you connect a meter or recorder to the output of the drive? You could monitor the actual voltage on the motor leads when the motor is stopped. If the drive is in a stop condition but voltage is present, then it is indeed regen. An alternative thought is that you may have a high input voltage condition. The high input voltage will cause a higher DC bus on the drive. When the DC bus gets high (either due to regen or a high input voltage), you will get an F05. If your incoming power is high, you can suggest gathering more info on the power supply. If it is always on the high side, you may need to change the tap on your plant's power transformer. If the trips occur only at certain times of the day or night, then it could be the power company switching their power factor correction capacitors. If it is a slightly high power or from a fluctuating incoming power, a line reactor could be added to the input power side of the drive (if not already equipped). Sorry for the brain-vomit- I just typed issues that I have seen in the past with variable freq. drives.

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I have only seen this occur when it recieves a run command .. We have several drives on the same power system and we aren't seeing these issuses only with this equipment...

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Just to be clear, does it trip when you tell it to start, or after it's been running a while? If you've ruled out problems with the incoming line, an over-running load is pretty much the only way you're going to get a bus over-voltage condition. I've seen a bad encoder cause it, but that's a different application). If the motor is spinning while de-energized, it's a pretty safe bet that there's a leak past the check valve (if I'm following your description correctly). How much more evidence do they need that there's a leak?

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Yes, if it faults it does it when it gets the command to run either from the plc or in hand mode.. It does do this all the time be is a nuisance..

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Is the motor already spinning when it gets the start command? If so, that's a pretty fair indicator that there's flow.

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This will raise the DC bus voltage and cause the drive to trip to protect itself.

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