On Friday, May 25, 2012 09:35:09 AM John Thornton did opine: > I can get the model number in a bit but it is a dual trace scope with > storage. The second trace would show up as a horz line so I'm sure I had > some knob in the wrong spot. I tried to follow the instructions but > could not find where it showed how to make a dual trace. It would be > nice to compaire at least one line phase to the generated phase. > > Thanks > John
For this it gets sticky, because you have 2 choices of how to attach the scope probes, BOTH of which leave the case of the scope lethally hot, so at the very least it has to be running on an isolation transformer, and sitting on an insulated table, no way around that. You'll obviously need to be standing on an insulated surface, and following the one hand in the pocket rule. The two methods would be: 1. Attach the probes ground lead to one of the phases, and the probe to one of the 2 phases, remove the ground clip from the 2nd probe (for safety) and attach the probe tip to one of the other phases. 2. Attach the scopes ground probe to the idler motors center Y connection, the N in that drawing, and probe the 3 phases 2 at a time. Obviously the scope is also on a wooden table for either setup and running on the isolation transformer. Take pix & post of course. Now, that said, I am not at all comfortable telling someone else to do all this that I would be comfortable doing and have done similarly in the past. These voltages are LETHAL! They are also above the probes voltage ratings, so I might build a Y type attenuator to reduce the voltages against the probes with a handful (15) of 2 watt, 100k resistors, 5 in series per phase leg, the probe the first resistor away from the center of the Y, the center also connected to the N point in that drawing. If you measure voltages from the scope, multiply by 5, but that is optional. It will give you peak to peak anyway, and will tell you if you need the higher than the std 370 volt rating capacitors for long term durability. And I'm still damned uncomfortable offering this advice, so please be careful John. I like that pdf, and I know where I can get both 10 and 15 horse motors for the idler. Our old transmitter was water cooled. But I don't have any 3 phase loads to run with it. Yet... Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> Yow! Now I get to think about all the BAD THINGS I did to a BOWLING BALL when I was in JUNIOR HIGH SCHOOL! ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
