AB 525 drive not ready alarm

The VFD for one of our conveyor motors had failed. Originally when it had failed it had powerflex 40 drive which was upgraded to 525. Yesterday an operator pressed an Estop button while the machine was running which shorted drive. Input voltage was measered at 270 VAC but output was at 4 VAC. The decision was made to swapp the drive. Now were seing an issue with it whenever conveyor stops for downstream it causes an alarm the VFD not ready. It is a resetable fault. Output voltage meausured at 4 VAC again. The drive shows no alarms and communicating properly. I suspect this drive to be a problem from stock. Any help will be greatly appreciated . thanks

There is nothing in a 525 that would display "Not ready", so that is likely something involving your control system. The closest thing is that you can program one of the Opto Outputs to indicate "Ready" (setting 0) whenever the drive is powered up. That is NOT the default setting though. The default for Output 1 is "Running" and the default for Output 2 is "At Speed". So if, in the original drive, one of those was programmed to be "Ready" and is wired to an input of your control system that is then expecting it to be thigh whenever the drive is powered, it will not be.


I also find it curious that hitting an E-Stop "caused" the drive to short out. What is your E-Stop doing? If it is opening a contactor on the output of the drive, that's not a great idea, but if it only happens on rare occasions (i.e. "emergencies", it shouldn't harm the drive. The reason it's not recommended though is because if it is done over and over and over, the arcing of the contacts when the contactor opens it stresses the transistors and can eventually lead to failure. the point is, if that is what happened, it might be an indicator that a lazy operator is just hitting the E-Stop every time he wants to shut down the machine. In that case, you should re-think the design.