PowerFlex 40E

[Armadillo852 25]

Hello again All, We are using AB Power Flex 40E with the 22E Comm module. When we open a safety gate, or hit the e-stop button, we kill power to the drives. When we power up, we have a 20 second delay time before we even look at getting a response back from the drives. The issue we are having is that every time we have this "power cycle," for lack of better phrase, we get a timeout from the powerflex. Now, this might be the way we do our fault message or maybe this is normal. I do not know. Does anybody know the length of time it does indeed take to power these drives back up and establish communications? If there is any other information you need let me know. PLC: 1756-L61 Rev.17.3 Ethernet: 1756-EN2T Rev. 2.1 (port speed and duplex set to auto-negotiate. Currently 100Mbps) Drives: Power Flex 40E with 22E comm module. Rev 6.1. Requested packet interval 80ms on some, 20ms on others. All depends on how much they are used. Thanks, Corey

[drforsythe 15]

I use PF40 drives with the ethernet module in our operations. I have also used the PF70 drive with 'Safe Off' feature. I have stopped cycling power to our VFD and servo drives during a safety circuit interuption. The circuits I set up utilize a safety relay with both immediate outputs as well as time-delayed outputs. When the interuption occurs, the immediate output from the safety relay will issue a stop command. This allows the drive to try to stop the load as quickly as possible. Then, after the time delay (usually 1/4 to 1/2 second) one set of time-delayed contacts will remove the "enable" signal to the drive and a second set of contacts will remove power to a contactor (safety-rated and monitored motor starter). The safety-rated motor starter is connected between the drive and the motor. It is important that you set the deceleration time of the drive to a value LESS than the time-delayed contacts in your safety system. If you break the connection between the drive and motor while the drive is powering the motor, you will damage the IGBTs on the output of the drive. This may not happen the first time, but over time your drive will prematurely fail. The above setup will increase the uptime of your machine because you will not have to wait for communication to resume. Also, it is safer because your motor will be physically disconnected from the drive (regardless of the charge state of the drive's capacitors). This method is recommended by most drive manufacturers to prevent premature failure of the input power circuit. A-B's website has examples of wiring on their website. Hope this helps.

[Armadillo852 25]

Thanks for the reply. I agree that method would be very nice. However, it is going to be hard to convince our parent company in Italy to change their design. Thus we are stuck with this design. We have a disconnect before the drive, but come off the drive right to the motor. So unfortunately I am stuck with what we have and just tell the customers to deal with it for now.