Learn About Factors Affecting Toroidal Transformer Size & Cost
The size and cost of a transformer increases when the Rated Frequency is the lowest frequency which will allow Max. Supply Volts without saturating the core.
The size and cost of a transformer increases when you move down the listing of primary windings. A 5-LEAD primary requires more copper than 2+2 primary. A LADDER is the least economical primary.
A transformer for 60Hz with a single primary will always cost less and be smaller than a multiprimary 50Hz transformer. The savings are often large enough to make it economical to use two different versions of a transformer, one for the domestic market, and another for foreign markets, in spite of the smaller lot sizes of each transformer.
DHW circuits and CTB circuits with unsymmetric load require a larger and costlier transformer than regular FWB circuits. Circuits with L-filter (FWBL and DHWL) require a smaller transformer than circuits with capacitor filter (FWB and DWH), but the inductor adds size and cost to the system.
The size and cost of a transformer increases rapidly when UP/ UPnom is decreased for constant output.
The size and cost of a transformer goes down with decreasing DUTY CYCLE, but the LOAD REGULATION increases.
If you specify more than one set of data for the same secondary, you do in reality specify LOAD REGULATION in addition to rated data. The AC LOAD REGULATION for a transformer varies with its Rated Power when it is designed for normal temperature rise, from about 20% for a very small transformer to about 2% for a large transformer.
If you specify data corresponding to a smaller LOAD REGULATION than normal for the transformer’s power rating, the size and cost of the transformer will increase.
If you specify data corresponding to a larger LOAD REGULATION than normal for the transformer’s power rating, your specification cannot be met without overheating of the transformer, unless you provide forced cooling and/or external resistors in series with the transformer.