More Toroidal Transformer Measurements

9/26/2003 N. Kitamura

1. Silicone-insulated 22AWG wire (10kV)

Objective:
Determine if the silicone-insulated transformer acceptable for the bifilar winding.

Samples:
Red: 18 AWG hookup wire, 10 turns ("Sample C" in the previous presentation.)
Blue: 22AWG silicone-insulated wire, 5 1/2 turns.

The 22AWG silicone-insulated wire (10kV) has a larger overall diameter than the regular 18 AWG hookup wire. As a result, only 5 1/2 turns can fit on the same toroidal core.

Result:
They had a very similar response. The silicone-insulated version is just as good as the previously-reported 18AWG hookup wire version.

Red: 18AWG hookup wire (sample C, 10 turns)
Blue: 22AWG silicone-insulated (5 1/2 turns)

2. Low-Temperature Effect on the Performance

Objective:
Evaluate the performance at low-temperature.
Sample:
Silicone-insulated 22AWG wire, 5 1/2 turns.
Procedure:
Measure the square-pulse response at room temperature, then put the DUT in a -30C freezer and repeat the measurement every 5 minutes.
Result:
o The low temperature has no effect on the rise-time and the fall-time.
o The signal level is attenuated by approx. 6% at -30C retative to room temperature.

A1..A8=Measured at -29C.
A0 = Room Temperature

3. Conclusion

o The bifilar winding of 10kV, 22AWG silicone wire on the same toroidal core as in the previous coaxial design has a satisfactory square pulse response.

o The low temperature effect on the performance is minimal and manifests as a slight attenuation (~6% from RT down to -30C). This, despite the known low temperature effects on the ferrite core, is presumably because the square-pulse response is dominated by the capacitive coupling of the winding.