How easy would it be to make some small solid state electronics be powered
by current flow?
I've been trying to imagine what it would take to make a circuit that could
be used to communicate optically the current level from a current transformer
with no metallic connection to the receiving point. What I imagine would be
attached to or made part of the current transformer itself. When there is
a sufficient amount of current, it would be able to power the electronics,
which would measure the current level, encode it digitally, and emit that
code over a low level LED. Nearby another electronics package powered by
other means would receive that code and know what to do with it.
An issue I see is that the electronics being powered by the current would
have to be able to operate on very low levels of current since anything below
that level would be unmeasured. But it would also have to operate on high
levels of current, and survive faults in the system being measured (spikes
of very high overcurrent).
It would also have to be highly reliable to avoid having to contact that
current sensing point for maintenance.
Also, given the high voltages involved, the sensing package would have to be
designed for that. I would assume it would need to have a permanent load
resistor, but it could still see a wide range of voltage drop across that
resistor as the current levels change.
14 years ago