What has more effect on size of transformer?

[FaradayFF]

Hi,
What determines the dimensions of the distribution transformer, the kVA rating or the impedance( ohms per phase)? I would think both, since if you wanted to increase ohmage value, you would wound additional turns around the magnetic core. Obviously, the larger the kVA rating, the larger the unit. I guess I am asking which has more of direct correlation to the footprint of the unit.
Thanks,
EE

 

[paulengr]

Hi,
What determines the dimensions of the distribution transformer, the kVA rating or the impedance( ohms per phase)? I would think both, since if you wanted to increase ohmage value, you would wound additional turns around the magnetic core. Obviously, the larger the kVA rating, the larger the unit. I guess I am asking which has more of direct correlation to the footprint of the unit.
Thanks,
EE

It’s more complicated than that. You’ve also got voltages to consider, core material, design (YY, YD, DD, etc.), cooling surface area, design temperatures, design as far as type of wire (flat vs round), type of winding, oil vs gas vs air cooled, fans...it’s not easy. Take a look at a large surplus dealer list like Sunbelt Transformer to get an idea.

 

[GeorgeB]

The ARRL handbook in my youth had a power capability for EI core transformers almost 100% based on core volume. ASSUMING the same frequency, many amateurs stripped some windings from television power transformers and wound their own secondaries.