1)  Determine the power level, output voltage and current.
Example: Power = 750 watts, Output voltage = 5 volts, Output current = 150 amps.

2)  Determine the required turns ratio, e.g., 8:1

3)  Select the type of module, i.e., FTI-12X2A - XX or FTI-12X4A - XX, by determining the output voltage.

For output voltages of 0 to 15 volts : Use FTI-12X2A series (2 xfmr cores)
For output voltages of 16 to 30 volts : Use FTI-12X4A series (4 xfmr cores)

For higher output voltage, please consult the factory. Modules with 6 cores for outputs up to 45 volts, and 8 cores for 60 volts are available.

4)  Select the number of modules required by determining the turns ratio and power level.
e.g., For 600 watts, a turn ratio n=10:1, 5Vdc @ 150 amps, select 5 modules of FTI-12x2A-21M17-A-1B or a FTI-12x2A-21M17-A-5B

5)  Calculate the number of primary turns by using the following formula:

M x N = n,
M= number of modules
N= the number of passes through the modules (or the number of primary Windings).

In this example, M= 5 (from #4 above), and a turns ratio of n= 10. Then N= 10/5 = 2 turns.

6)  Calculate the wire size for the primary winding by determining the primary windings current. For the Flat Transformer, only 50 circular mils per ampere is needed. Larger wire sizes will provide better efficiency and lower copper (wire) loss. (A conventional transformer requires about 500 circular mils per ampere).

In this example, the power level is 750 watts with a 5 volt output. Assuming a Half Bridge configuration, and a turns ratio of 10:1, the input voltage into the transformer is approximately 150 volts a.c.. The current through the primary winding is 750/150 = 5 amps. The wire is calculated to be 250 circular mils. For a safety factor of two, 500 circular mils, or AWG #23, is selected.

7)  Choose the correct wire insulation. Teflon coated or triple insulated wires are recommended for good dielectric isolation. The FTI series module adds a teflon sleeve between the primary and secondary windings. By using teflon coated wire together with the teflon sleeve, a breakdown of over 40,000 volts can be achieved.