Aboutcleggsan Expertise All technical areas of Electronics Engineering.
Experience BSEE, MBA, Design, R&D, University Research.
Senior Life Member of IEEE. Life Fellow of AES.
Organizations IEEE, Consumer Electronics Society, Audio Engineering Society.
Broad teaching experience; work experience mostly in consumer electronics and conversion from analog to digital technologies. Pioneer in digital audio at all levels.
Expert: cleggsan Date: 6/25/2008 Subject: Ringing Effect... Follow up
Question You wanted to know more about the situation and I could not access my university email to get the link to ask a follow up question so I had to do this.
Hopefully I can explain this a bit better. To start off, the thickness of the wire is 4/0. In detail, this is written on the wiring: "T90/TWN75 NYLON FT1 CSA LL35335 (UL) THHN OR THWN OR GASOLINE AND OIL RESISTANT II OR MTW 600V VW-1 4/0 AWG E101805". So basically, from the secondary part of the transformer (wye), cables run to the MCC, then out to the motor that runs the edger where the problems occur. The distance from the MCC to the motor is approximately 600 feet.
Now there is 120 VAC supply, and it carries on to the load. Just after the load, the voltage is measured as 6.7V when it should be relatively close to 0V to 1.5V (max). So to fix this situation, a jumper was placed (I believe it was 18 gauge wire and about 2 feet long) from the neutral to I believe the equipment ground. Now I am to help try and figure out why this is happening and fix it. The motor itself is also a wye type. Now these readings may have to be taken again, but there was 5.7A flowing through that jumper (it recently burnt/corroded through and was replaced) and from the equipment ground to the main mill ground there was 4.2A. I was told there were 2 other grounds connected to the piece of equipment and grounded somewhere which may make up for the 1.5A difference. The 4.2A cable is connected to the main ground which and this main ground carries a current of 16.7A at 60Hz which leads to the PDC and then out into the yard where it's buried/grounded.
The mill has only been operational for almost 2 years so it is fairly new and this has been a problem since the beginning.
Thanks again for any advice or help,
Luke
Answer I am more confused than ever. I am going to have to have an overall schematic and block diagram of the equipment and inter connections.
You could email me a drawing or reference diagram to cleggsan#cleggsan.com if you wish.
Normally, there would be very small voltage differences among the grounds. If there exists a potential difference of more than a volt or two it is an indication of either a wiring problem among the grounding or an equipment malfunction.
Do you have a clampon ammeter to measure the current accurately?
And, I am worried about your voltage reference points; voltage does not flow through.... voltage is across a circuit element. Current passes through a component or wiring, but does not go across. So you confused me on those terms.
Also, it would help if you were to give me the make/model of the transformers and motors and their ratings/specifications so I know what level of machinery you are working with.
