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Learn About Factors Affecting Toroidal Transformer Size & Cost
Supply Frequency:
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.
Primary Configuration:
Another factor affecting cost is 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.
US/Foreign Version:
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.
Rectifier Circuit:
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.
UP/UPnom:
The size and cost of a transformer increases rapidly when UP/ UPnom is decreased for constant output.
Duty Cycle:
The size and cost of a transformer goes down with decreasing duty cycle, but the load regulation increases.
Load Regulation:
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.