This Blog thing and other stuff

I have been writing articles for this blog thing for about a year now with very little feedback from anyone. I have done this hoping to inform anyone that reads about troubles we have found on service calls, new information from our suppliers and anything else that I happen to think about and have the time to type up and post.




No feedback tells me that what I am writing is either not important, taken as gospel or just not worth the time to comment on, I wonder which if any it is.



Ran into a situation lately where a customer is having a problem running drives that have harmonic trap filters on their back-up generator. It seem that the capacitors are causing a voltage rise that the generators voltage regulator cannot compensate for. This causes the generator to shutdown on over voltage.



The factory is looking into this issue. The application engineer sent me an email stating that he was going to do a write-up on running VFC’s with HTF’s on generators but I haven’t seen anything as of today’s date. As soon as I see this, I will make sure and follow up with another post that addresses this issue.



So if you read this and are interested in the solution to this problem, keep following the post. If you are not, you probably didn’t read this to begin with. Either way it’s fine by me.



Hello, anyone out there?? Damn, nice echo! Echo, echo, echo……….



Scott

The importance of proper grounding

An interesting thing happened yesterday. I had been talking to a customer that had purchased a new VFC to replace one that had gone bad in a Motor Control Center. He told me that the 4-20mA signal was acting very erratic and that the drive would not follow the signal.




I went to the site and sure enough, the signal was all over the place from zero to maximum and everywhere in between. We looked at everything from cable routing to the shield ground connection but still didn’t see anything.



I replaced the control board at this time thinking that maybe something was wrong with it. I asked him to power the unit back up and when he did he received a small jolt. I quickly measured the potential between the VFC chassis and the ground in the panel and there was 67 volts…..No ground strap on the chassis to the panel.



Here’s the lesson, the paint on the steel chassis of the drive is a thick powder coating and it will not ground just by the mounting bolts. US Drives provides two ground terminals near the input/output connection points for not only connecting wires for incoming and outgoing but also for a connection to the equipment. There must be a solid ground for the drive and this one was floating.



Right after we ran a ground the signal worked just as it should. Lesson learned.



Just thought you should make note of this.



Scott

Elko Mining Expo

We will have our trailer with products and demo's at the Elko Mining Expo in Elko, Nevada this coming Thursday and Friday.  That's June 10th and 11th.  If you are in the area, stop by and say hello.  We will be on the north side of the expo center in the display lot.

Scott