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Re: Current Transformers




> Date: Tue, 2 Jan 1996 18:08:23 +0700
> From: chip (Chip Atkinson)
> To: tesla
> Subject: Re: Current Transformers
> 
> >>
>     If there is a 400 stamped on it is a 400:5 CT meaning if 400 amps
> flows in the primary 5 will flow in the secondary.
> << 
> Actually, it has "400:1" stamped on it.  I think that's a little better
> but maybe not the best.  I was able to make a new scale for a 0-100 ma
> AC ammeter to read 0-40 amps.  This should do for now.  
> 
> >>>
> Our local electronics surplus has piles of the smaller ones
> (100:5 and lower) for about five bucks a piece.
> <<<
> Care to do any "remote buying"?  What's their address?  Perhaps
> I could talk them into mail order.
> 
> Chip
> 

400:1 is a pretty atypical marking for a CT. That would normally be marked
2000:5 and would be used for metering a pretty large xformer.  Have you 
tested the accuracy of it at the power levels you are using?  I'm
curious as to how it performs.

I forgot to mention these things have polarity markings.  The "dot" or H1
points towards the source.  On the secondary side X1 is "hot" and X2 is
usually grounded.  Polarity probably doesn't make a difference on a single 
phase circuit but it can throw a wrench in the works when dealing with 
three phase metering.

I haven't been to any of the local surplus stores for about 4 months
because of the trip I took.  I'll try to get around next week sometime
and see what they have that would be of interest here.