i am trying to figure out a CT (Current Transformer) which is installed in my device of analysis. This CT has Two wires passing through its center hole (one is phase/red wire of single Phase AC supply and the other is neutral).
I don't know the specifications of it, because there is no marking over it (probably locally made) nor i have a datasheet or something.
So, i applied different values of ac current through it and noted down the current at secondary of this CT using Multi-meter's Ammeter Function. I came to know that, its turn ratio is Ns/Np = 0.01. It means for current flowing through one primary conductor is 10A, the secondary side output current of 0.1A.
The problems, i am facing are these;
1- When the current of 10A is passed through each pf primary conductors (phase and neutral passing through center), and the current is in same direction (in CT, direction of current is same in both conductors). The output secondary current is approx. zero. If the current is in opposite direction, the secondary current is 0.2A. How is this possible? In case of different direction, the resulting flux should cancel each other and no secondary current should be present and vice versa? But i am getting opposite behavior?? is there any possible internal structure that makes it work??
2- As far as i read about CT, their secondary current is independent on load impedance. It means if primary current is fixed, secondary should have been fixed no matter impedance of load is.right? But if is simulate this in Orcade PSPICE, changing the load impedance changes the value of secondary current although primary current source is fixed at some value.??
3- I know the secondary current based on primary current and turn ratio. But since CT;s are used to sense current, one actually sense the voltage at secondary of CT whose value is corresponding to primary current. But how do i know this secondary voltage at CT? Because at the output of CT, a bridge rectifier is attached and some RC circuit, so to find the ripple factors, values of ripple voltages, i need to know what voltage is appearing at secondary of CT. How do i find that??
Thanks in Advance..