Current Transformers

I'm not familiar with them, but I need to use one for an experiment and I don't understand all the different specs the mfrs provide. I don't understand the limits of burden resistors and how to vary either voltage or current from the specs and just how hot the transformer or the load will get under different v/a results. I can go further with my queries, but 1st I have to know more about how to use these things.

 

When using a current transformer you must never leave the secondary winding open circuit because high voltages will appear across it if there is current through the primary winding.

Have a look here:

http://www.allaboutcircuits.com/vol_2/chpt_9/7.html

 

Current transformers are mainly used to step down the current in a ac power or current measuring circuits.By stepping down current from few hundred amps to 5amps (low amps) it allows a small ac ammeter to be connected on a control panel, so that one can easily see the current supplied by any generator or ac power source.
They are also used inreactive power and real power sharing circuits of parallel operation of generators. The current transformers will be connected in power sensing loop,then a burden resistor is placed across the secondary to develop an error siganal which willbe used by control circuitry .
They are also used in differential current protection and over current protection circuit of power system.
While selecting the current transformer for any application you need to consider the magnetizing current,ampere range of primary and secondary.
When a current transformer is connected in a circuit ,the secondary should never be open , the high volatage developed across the secondary can burn the transformeror can can pose high volatage shock hazard to persons if accidentally come in conatact with secondary.