Toroidal transformers offer many advantages over standard laminated power transformers.... Toroidals provide quiet, efficient operation with very low stray magnetic fields.... More efficient use of the core material in a toroidal can result in a size and weight reduction of up to 50% (depending on power rating).... The windings are evenly wrapped over the entire core allowing the transformer to operate at a higher flux density than in standard transformers.
..."Toroidal transformers offer many advantages over standard laminated power transformers..."
It makes no sense :
1 ) There is possible to build an Toroidal transformer even laminated.
2 ) Lamination reduces Foulcaut losses effect.
To construct the core, grain-oriented silicon-iron is slit to form a ribbon of steel which is then wound, like a very tight clock spring. The result is a core in which all of the molecules are aligned with the direction of flux. Molecules not aligned with the flux direction increase a core's reluctance (the capacity for opposing magnetic induction), degrading performance to the level of common steel when the molecules are 90 degrees out of phase. EI laminated cores, which are stamped from grain-oriented Si-Fe, may have as much as 40% of the total core area perpendicular to the ideal grain direction, with another 40% acting only as a return flux path. This more efficient use of the core material in a toroidal can result in a size and weight reduction of up to 50% (depending on power rating)
So, it´s visible just looking at each type, that don´t have substantial difference in size.Ae = SQUARE_ROOT ( P )
P - Output power [watt]
Ae - Effective area of cross section[cm2]
The quote I posted is from here: Toroidal Transformer Basics... I wish know the reference...
In some cases, toroids can be much much smaller than laminated EI, since for the core area the windings are also taken into account, and core can be very small inside. The core itself is one piece which is grain oriented in the direction of the flux, which allows for higher flux, in turn allowing for much more power for it's size.The numbers seems exagerated.
Actually your background does explain your point of view a lot, since toroids are almost never used in SMPS design. It's hard to spread few turns of wire around the entire toroid. And winding of the wire gauges used are virtually impossible to automate.I worked many years ago with power electronic in development of UPS and SMPS and my opinion was based on self experience.......
There are many advantages of EI types over toroids, and you've missed almost all of them. Like how the air gap in the EI type helps filter out the 'dirty' mains power. How EI cores can deliver much more current in peak because of their higher inductance. Or how the toroids are much more affected by the DC offset in the mains (from switches, motors, etc...). And so on...The fact is that beyond the advantages highlighted...
True. And production is very hard to automate, in some cases virtually impossible (like in SMPS mentioned above).Winding must be performed around ring structure, being more vulnerable to mechanical shock than EI
Yes and no. Yes from a mechanical point of view. No from the electrical. But smaller overall size makes up for it :wink:Space inside Toroid type (hole) is wasted, in opposition to other types
Actually no. They are easy to mount. They are squeezed between a plate on top and a casing (or where it is mounted) on the bottom, with rubber sheets in between. Just one screw trough the middle and your set. And there is no worrying about the noise because toroids are not susceptible to magnetostriction like other types.Due it rounded aspect, without plane surfaces, it is hard to place, and is needed a bracket.
I'm not aware of standard power supply transformers utilizing an air gap. Strictly spoken, toroidal transformers also have a small built-in air gap, by the small non-magnetical spacing between band windings.There are many advantages of EI types over toroids, and you've missed almost all of them. Like how the air gap in the EI type helps filter out the 'dirty' mains power.
TOROID : T 140/106/15 # Ae=422[cm2] / M=800[g] / MaxDimension = ~106[mm]
EE : E 55/28/25 # Ae=420[cm2] / M= 130*2[g] / MaxDimension = ~56.2*2[mm]
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