DNP3 ethernet communication problem MV relays

[martinrelayer]

hello,

we have here small distribution switchgear 33kV, each breaker has it's own relay (Schneider VAMP Relay 255) connected to SCADA by DNP3 over ethernet (10MBps) all vamps goes to standard Cisco switch, ethernet cable is category 6 UTP, no shielding, vamps earth connection checked and so. Eight relays in local network, uplinks to the rest of the relay network with no problem.

we have several communication alarms, more or less every half an hour, of a communication loss on DNP3. The problem starts when connecting the voltage measuring to the relay!

we have one metering section to 33kV/100V secondary and that daysy chains to all feeders to a MCB three phase, if I connect the voltage metering the communication problem starts! One fault every 25mins, then start again automatically and so (see attachment)

I don't know if it's earthing problem on some spot with wrong earthing or if it's electric field affecting in some way

Does anyone has any similar fault, or any hint to solve this??

kind regards,
martin

 

[FreddyNurk]

Based on your description I can't really tell whether to start looking at the communications side, or to look at the metering side.
Whats in the metering section that you're connecting?
Is there a comms capable device that only runs when the metering section gets connected?

There are likely approaches in either side that may assist, such as accessing the local network when the communications goes down, and seeing if you can still get a response from the relay, but I'd be loath to recommend one way or the other without a bit more information.

EDMS Australia

 

[stevenal]

How long are your cat 6 cables?

 

[martinrelayer]

they are 10 meters long