Difference Between Toroid and CT

A current transformer could have any core type including toroidal. This doesn't mean that all core types are a good choice but any could be used.

A current transformer has material selection and winding characteristics to make it good for the application of "current transformer".

A toroidal core transformer has a toroidal core.

You seem a little confused. If you do a little more research on current transformers and other step up/down transformers I think you will see that your question is a little like asking if there is a technical difference between a tire and a car. At first exposure it might seem like a good question but after you learn a little more you will see that the question (and possibly your current efforts) don't make sense.

Keep trying but it might be good to try to find a fresh and different way to work on it.

A Toroid is

• A figure with a shape resembling a torus.
• A coil shaped like a torus or doughnut.
• A toroid is a doughnut-shaped object, such as an O-ring. It is a ring form of a solenoid.
• Toroidal inductors and transformers are electronic components, typically consisting of a circular ring-shaped magnetic core of iron powder, ferrite, or other

Toroidal cores have the advantage that (a) they are easy to wind from a continuous strip (usually of CRGO) and (b) since the flux lines are always along the preferred grain orientation of CRGO, losses are minimal. Especially for bar-primary CTs. C shaped or E shaped cores are made from stacking strips of laminations, binding them together, so on. More manufacturing effort, and losses usually higher due to non-ideal grain orientation.

A CT is an electrical device, which may use a toroidal core of magnetic material.

I agree with you generally on the low-leakage advantage of toroidal cores, but I have to disagree about toroidal cores having an advantage when it comes to manufacturing effort.

.

Not all cores are constructed from electrical steel. Making an E core out of ferrite isn't appreciably more difficult than making a toroidal core out of ferrite.

.

More importantly, most toroidal cores require significantly more manufacturing effort for windings. Toroidal cores require the bobbin to be passed through the core for each winding loop. Whether accomplished by hand or machine, it requires a significant investment.

E cores allow the winding to be manufactured independently of the core and placed on when finished. This is far quicker and typically far cheaper than winding a similar toroidal core.

An advantage of toroidal cores in POWER transformers is less interference inside a device.

Ah yes of course, but i did say a continuous strip of CRGO...

A toroidal shape - has least material content for core for an enclosed magnetic path- hence least cost construction. A toroidal core selected for CT applications does not have any cuts or air gaps. A EE or UU core can be fitted with a bobbin which can be separately wound and fitted over the core later(but a split core of this nature has a air gap- however small). Winding toroidal cores needs special toroidal winding machines. Other than that circular toroid shape itself has less significance. Even toroidal CT can be influenced by external magnetic field by holding magnets to change the operating point on the BH loop of the magnetic core.

BruceFlorida is right - your question is confused, and the other posts are more about some of the physical realities of making a transformer.

The basic rule is that a current in a coil of wire produces a magnetic loop (you might think of it as a line of magnetic current) - this is drawn as a line of magnetic flux that connects with the current loop much as two links of a chain.

When the current reverses, the direction of the flux line reverses and the faster the current is forced to change its size or direction the greater the back voltage induced in the current coil by the changing magnetic flux line that works against the intended change of current - i.e. it tries to keep the current flowing the same way.

The amount of current and magnetic flux is largely determined by the driving voltage and the magnetic resistance of the magnetic path. In air this is high and it takes lots of current and turns of wire to produce a unit of magnetic flux, BUT if the path is a toroid of something like soft iron then the magnetic resistance is low and for all else equal, the current is less. If the core is a "E" shape or a "bar" then combination of air and iron for that magnetic path gives a result somewhere between the "all air" and "all iron toroid" examples.

A transformer is just two of the above current coils interacting where the voltage and current in one coil is connected by the flux of the magnetic circuit to the other.

Losses occur when the magnetic field is reversed in something like iron, but not when in air. Losses also occur in the electrical coils because these have electrical resistance (super conductors could be used to avoid this). There are also design issues like the fact that iron cores are only "good conductors" for flux up to a point at which time they saturate and don't readily allow more flux density or magnetic current to increase.

And of course in an E or bar type core there can be magic leakage where not all off the flux created by one coil connects to and reacts with the other coil.

Your question would be better framed as something like, "is an E or toroidal core best for the construction of a current transformer".

The answer is, "depends on your needs" for size, efficiency and noise etc. as all transformers transform current and voltage according to the same overall energy rules i.e.

Vin/Vout = Nout/Nin and

Vin x I in = Vout x Iout,

except for quite small losses.

After going through all the contributions i was a little embarrassed. I realised i was making a fundamental error. Thank you all for your contributions, now i know better.

Don't be embarrassed when you realize you have made a fundamental error...

....people who don't realize they have made fundamental errors don't ever correct them.

.

A CT is a current transformer used for detecting or calculating current without passing through the meter the current of the actual load.

CT transmits a show current through the meter, which reads the current, as the CT.

A toroid is a transformer core, in the shape of a doughnut that is significantly more efficient at magnetic coupling than a typical laminated-iron core.

At higher frequencies, they are particularly efficient and require less magnetic discharge from the core and more primary energy is combined with secondary.

A toroid core should not use a CT.