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More About No-Load Operation In Current Transformers—Creating Real World Models

by Gregory Mirsky, Vitesco Technologies, A Spinoff Of Continental Automotive Systems, Deer Park, Ill., How2Power Today, Aug 14 2020

Focus:
A previous article analyzed the operation of a current transformer (CT) in idle mode (i.e. with no load) with the goal of determining whether the CT was in danger of experiencing core saturation or a dangerously high secondary voltage. This article continues the discussion by clarifying various aspects relating to the previous modeling of the CT secondary voltage under no load. The author elaborates on his choice of the exponential function for the rectangular- shaped primary current waveform, the meaning of those unitless constant terms, and how the timing parameters equate to readily available data sheet parameters for power MOSFETs and CTs. Finally, he plugs in some actual component values for a design example, to see how the model for the CT secondary voltage under no load can be applied in the real world. As part of this discussion, he considers the real world case where rise and fall times of the pulse are different, discussing some tips for making the analysis easier.

What you’ll learn:

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