wwhitney
Senior Member
- Location
- Berkeley, CA
- Occupation
- Retired
Hello,
I'm trying to understand current transformers a bit better. The main thing I'm unclear on is the exact difference in transformer construction or installation that makes the transformer output behave like a current source versus a voltage source. It seems like in both cases the transformer consists of a core with two coils wound around it, although in the CT case the primary coil is typically a single loop. A few related questions:
1) Typical AC electrical systems are fed by a constant voltage source (the grid). So the only difference in installation I see between a CT and a VT is that a CT primary is connected to the voltage source in series with a significant impedance (the load through which you wish to measure the current), while a VT is connected through just the impedance of the wires. Is that the key difference that makes the output behave as a current source instead of a voltage source?
2) Say I have a 120V/12V AC doorbell-type transformer, i.e. a 10:1 turns ratio (no compensation). Suppose the coils on both sides have sufficient voltage rating, if I hook up the nominal 12V side to 120VAC in series with a load, does the transformer behave like a 10:1 current transformer?
Thanks,
Wayne
I'm trying to understand current transformers a bit better. The main thing I'm unclear on is the exact difference in transformer construction or installation that makes the transformer output behave like a current source versus a voltage source. It seems like in both cases the transformer consists of a core with two coils wound around it, although in the CT case the primary coil is typically a single loop. A few related questions:
1) Typical AC electrical systems are fed by a constant voltage source (the grid). So the only difference in installation I see between a CT and a VT is that a CT primary is connected to the voltage source in series with a significant impedance (the load through which you wish to measure the current), while a VT is connected through just the impedance of the wires. Is that the key difference that makes the output behave as a current source instead of a voltage source?
2) Say I have a 120V/12V AC doorbell-type transformer, i.e. a 10:1 turns ratio (no compensation). Suppose the coils on both sides have sufficient voltage rating, if I hook up the nominal 12V side to 120VAC in series with a load, does the transformer behave like a 10:1 current transformer?
Thanks,
Wayne