vfd inverter for Myford

I think i may have been a bit wrong with comments about filters. This is an insert from Inverter supermarket site. My inverter has an inbuilt EMC filter & i as always use screened & earthed at one end motor cable. It seems some imported versions from ???? have not got the required filters built into them.

Steve.

It is more important to use motor wires that are screened, armoured or completely encased in metal conduit. This reduces the leakage of EMI and offers a conductive path back to the Inverter (required for EMC compliance in any case).

The Parker SSD Drives products we sell up to 7.5kW all include EMC Filters to the First and Second environment, as long as they have '-F-' in the product code. Most of the others include Second Environment filters, unless they say otherwise.

One thought for those who have had RCD trips from VFDs with filters - what was the leakage current BEFORE you added the VFD?
A typical household RCD trips at 30mA (differential between live and neutral currents). But a EMC filter leakage to earth (caused by the "Y" capacitor(s) is less than 1mA for a simple filter, about 5mA for a VFD filter or 15mA for a high performance filter. Given these figures even a high performance filter should not cause a trip. It is likely that the existing wiring and equipment has used up most of the leakage "allowance" and the VFD filter pushes it over the edge. Not if the existing current is from filters, that's not too bad, but it could be due to degraded wiring (for example google "green goo cable".

If your VFD filter trips the RCD it might be time to get a competent electrician to check the house wiring.

Robert G8RPI.

Probably not a problem these days but CRT computer monitors are a bit leaky, an office had five fed from one RCD that would hold any four but all five would trip, for some reason a 10mA trip was fitted so it was super sensitive.

Mike

Way back we had to excuse quite a lot of office equipment from the PAT test leakage test, due to a lot of equipment having padding capacitors around the chassis ,connected to earth. We used to get some weird readings.

After contacting the aapropriate manufacturers of the equipment we skipped the leakage test as directed by the Electrical engineers at the Blue chip companies we contracted to.

Note to oneself put all your Inspection & testing meters on fleabay.

Steve.

Andrew, do you suffer any nuisance tripping with the Siemens VFDs? I considered getting one but the documentation states to avoid nuisance tripping an RCD must be type-B 300 mA. The RCD serving my garage is only 30 mA and I do get occasional nuisance tripping with a Eurotherm VFD.