current transformer

I think it should be wired as follows: Run the wire you desire to measure the current on through the hole in the non-gauge unit. Connect the gauge unit to the non-gauge unit. Excuse my poor drawing skills:

The basic idea is that every electrical conductor creates magnetism perpendicular to it when there is current running through the conductor. These units read the magnetic induction with your electromagnetic coil (the grey hollow thing) and then, because magnets are capable of making electricity (think alternator / generator in car), turn that back into an electrical reding to your amp gauge.

Run the hot or common line (but only one) through the middle of the coil and then connect the terminals to the amp meter. You might want to get a smaller amp meter, 0-15 would probably read quicker.

Well, it is only a 0-20 amp meter, 0-15 wouldn't make a lot of difference.

For exact wiring instructions, better pictures of the terminals on each part would be useful.

The two silvery metal strips to the right of the photo are shunts, which are used to reduce the amperage running through the coil of the meter. The shunts are designed to allow very sensitive meters to be used on sources of larger currents, and are installed across the meter terminals in parallel.  I would suggest that you use an ammeter that is designed to be wired directly into a track circuit, without the necessity of shunts or remote coil devices. They are inexpensive and easily found on auction sites and in electronic catalogs.

Steamwolfs wiring is correct except for the physical location and method of connection to the meter(my experience, you need to provide a physical method to safely shunt out the meter). The bars on the right look like shorting bars. Current transformers should never be connected without a load(meter or shorted leads). If you need to disconnect the meter while there is current flowing through the CT(Current transformer) you carefully short the meter out. Because it's a CT, then if without a load connected it can develop a very high voltage on the secondary winding that goes to the meter. Actually, depending on the current, a very high voltage.

Most CT's standard output is 5 amps. A standard 200 amp CT would then be 40:1 ratio.

Don't be fooled by the low 20 amp rating. The CT will generate the correct voltage to maintain the CT ratio.  All the CT's I've worked with are shipped with the shorting bars installed.

I would research before you use this device. Kids like to touch everything.  Look up the manufacture and call their tech support. I answered this post because I've seen people get some serious shocks not realizing how high the voltage climbs to without a load connected to the CT when there is amperage flowing in the primary wire.

Arthur, sorry, you answered before my reply. The bars on the right look to me like shorting bars. I could be wrong. I would read the current like you suggested. Usually the output from the CT goes to a terminal block (not directly to the meter) where you then connect the meter to. The terminal block is spaced to the size of the shunting bar. To disconnect the meter under load you install the shunt on the terminal block which will short out the CT. Then you can safely disconnect the meter (at the meters connections, not at the terminal block, you always need to keep the secondary closed). This looks more like a device to be used in the electrical field rather than a hobby environment. Going by the picture there are two shorting bars. One for the transformer(CT), and one for the meter.

pops3301 posted:

Steamwolfs wiring is correct except for the physical location and method of connection to the meter(my experience, you need to provide a physical method to safely shunt out the meter). The bars on the right look like shorting bars.

Yeah, my bad, completely missed the shunt strips. That would have been an... electrifying experience!

I'm using a similar eBay meter, looks exactly like it but with different hardware.   I wired one side to my TPC 300 'U' and a wire to the center rail goes to the other. The meter completes the circuit; no shunt required.

Dennis

Sorry, got that backwards. One side of the meter goes to the "A" output of the TPC 300 and the other goes to track center-rail. 

Dennis

I have the same type of meters. A few pictures might help. The first three are of

my test transformer and show how the meter is "hooked-up" I'm using the

"U" side of the transformer, but AMPs don't care. Last two are of my panel for the layout.

Hope this helps.

Joe

I use a similar setup for 2 meters on my layout.  By using this method you do not have to have a large gauge wire going to the meter from power source to load. Another advantage is the meter can be located any where.

Thanks for all the input ,Joe your pictures help.