Ammeter Setup not Behaving

[tom66]

Re: Ammeter Setup not Behaving

You need to match the output of the CT with the scale of the meter. Using a resistor in parallel can help decrease the output of the CT, so you could overwind it, then reduce it with a resistor (or calibrate it with a pot.)

[pentium]

Re: Ammeter Setup not Behaving

This is over a year old but I'm going to wrap this thread up because someone linked me back to it when I was finishing this setup off today. Yeah, apparently it's that visible on google.

Anyways, it was all completely wrong. The meters had the wrong windings, the current transformers did NOT need the single wind and as a matter of fact, one CT was completely dead.
I ordered a new set of ammeters that shipped with matched 50/5 CT's (url=http://www.ebay.ca/itm/130894315346?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649]the listing if anyone is interested) so this time we were positive that it was going to work. When it arrived I found the meters were smaller than described (53mm x 53mm as opposed to the advertised 72mm x 72mm). Thankfully because the internals are identical down to the mounting points I was able to transfer the guts into the larger meter assembly at the expense the needle is shorter than it usually is.
Now that we have it all assembled it works. I can do something like plug in my weller and I can see the current draw rise. I can spin up the 12" hard disk and the starting inrush surges to 35A before settling back down at 10A. I'm starting to regret using a 50A scale but it's going to cost too much now to replace everything so I'll live with it.

This mystery is officially solved.