DeltaV Input Card Issue. Help needed
DeltaV Input Card Issue. Help needed
(OP)
Control loop for motor with VFD . One cable Start, running indication, + another for 4-20MA speed control. Running indication is Dry contact (Delta V 24VDC input card) taken out of VFD (Toshiba).
When everything ready to go ,channel status LED on the input card is blinking. Checked voltages and found out some AC voltage (30VAC) coming from the VFD. Checked the cable(it is long 5 stores up) megger is OK. When power is down for this MCC everything is fine. Another strange thing, we have almost the same package next to this and do not have any problem. Only difference is different VFD (Danfoss). I think this is a grounding issue, because there is no separate ground for power and instruments at the plant. Have to figure out what to do.
Thanks
BB
When everything ready to go ,channel status LED on the input card is blinking. Checked voltages and found out some AC voltage (30VAC) coming from the VFD. Checked the cable(it is long 5 stores up) megger is OK. When power is down for this MCC everything is fine. Another strange thing, we have almost the same package next to this and do not have any problem. Only difference is different VFD (Danfoss). I think this is a grounding issue, because there is no separate ground for power and instruments at the plant. Have to figure out what to do.
Thanks
BB





RE: DeltaV Input Card Issue. Help needed
If it was installed i would check the parameter list to make sure no one fat fingered a default parameter into an unknown state.
What is channel status mean? Is this on the vfd or on the plc deltav?
Usually there is a status word code in the vfd that tells u why its in this state. Go to this word.
Check the last fault, usually holds 16 to 32 past vfd faults
RE: DeltaV Input Card Issue. Help needed
everything was working on Bailey same VFD same cable just different input card for dry contact 24VDC instead of 48VDC. Stadus LED on the Deltav Input card. No fault on VFD. I guess this AC "background" was OK for 48VDC on Bailey but critical for 24VDC nominal and 15VDC actual on DeltaV. Thanks for your suggestion to check the VFD parameters.
RE: DeltaV Input Card Issue. Help needed
Have you tried loading the input down e.g. something like a 10K resistor to ground on the running feedback wire. Or perhaps a small capacitor to ground.
Regards
Roy
RE: DeltaV Input Card Issue. Help needed
Now just curious, Is it common in the US do not have a separate ground structure for power and instrumentation(control) If yes it should be a lot of similar issues.
RE: DeltaV Input Card Issue. Help needed
Having a seperate ground I equate to standing in a Faraday cage with your arm stiking out through the bars.
That's my 2c worth
Roy
RE: DeltaV Input Card Issue. Help needed
Having said that, the conductor sizes that DeltaV calls out for their signal grounding conductors are absolutely, ridiculously huge. My opinion is that if their equipment is that sensitive to noise then I don't want to use it.
RE: DeltaV Input Card Issue. Help needed
Sorry for off topic. I do not like DeltaV, but have to deal with it.