I've found on some of the well sites I work on that when the VSD is running the noise takes out the freewave telemetry. As soon as it stops the comms come good again.I checked the earthing of the well site,checked all the cabling of the well site (cables are all SWA as its hazardous area),ran new equipotential bonding off the drive but none of it seemed to stop the noise.It wasn't until I insulated the aerail and lighting arrestor from earth for the freewave radio that I was able to get good comms again with the VSD running.I've found that the bigger the pole the aerial is mounted on the more noise it seems to pick up.Also when the freewave has a weaker signal to its master the noise takes it out again.I have spoken to the manufacturer s for the skids for our well sites as well as the telemetry guys and no one's sure of why its occuring.What I have done is a temporary fix with insulating it from earth but was wondering if anyone had any advice on where to go from here.Thanks for your help.