PowerFlex-250KW Communication issue

[prakasha]

Hi Everyone,

We went through a tough time that Power flex-250KW Drive Thyristor burn out and MCCB tripped at feeder side, but in SCADA VFD was showing running and non of the interlocks were activated due to Old values were showing in PLC. Why and How will this happen and is it a normal phenomena that PLC doesn't updates when this unexpected things happened like drive burn out.

It it possible to take heart beat signal from Power Flex dives to update communication status between PLC & VFD.

Or Hardware wiring can be done for drive healthy status.

Kindly respond this query as this is very much concern to me

 

[Steve Bailey]

The details will always depend on the connected equipment and the communications protocol. It is the responsibility of the system designer to anticipate that communications will be lost, to provide a means to detect the loss, and to decide whether any data exchanged between the devices should revert to a default state or hold the last state. That is true for devices on both ends of the wire.

 

[Ken Roach]

>in SCADA VFD was showing running and non of the interlocks were activated due to Old values were showing in PLC.

It is 100% normal for the last valid data to remain in the PLC memory when a networked device connection fails.

Some people insist that all the values should go to zero, to indicate a failure. But all-zeroes is also a valid state for many devices.

A well-written PLC program will monitor the network connection or logical connection status to a field device, and react appropriately when that connection fails.

Every network connection method to a PowerFlex will have some kind of status data available; a GSV to the Module object over ControlNet or EtherNet/IP, a status bit in the scanner on DeviceNet, a Rack Status bit over RIO.

Or, as you suggest, a hardwired "status" bit from the drive's onboard I/O can be wired into a PLC input. Digital Output 1 on a PowerFlex is set by default to represent the "Fault" condition.

 

[prakasha]

Thanks a lot for your quick response