On Wed, 13 Apr 2011 09:57:33 +1000, "Phil Allison"
wrote:


"Dave M"


That's not true. an open rectifier does not allow DC current to flow
through the secondary. It's just 1/2 of the power line cycle. During the
opposite half of the cycle, no current flows in the secondary.

** So the average value is non zero and that means there is a DC component
to the current.

True, it's unidirectional current, but it's an intermittent current, not
constant DC.

** It will show a nice, steady reading on a DC current meter.

The interesting thing is how there is no corresponding DC component in the
primary current.


.... Phil

Unless the half wave rectifier is on the PRIMARY side.
I don't see any evidence of that on any of the diagrams I saw, but is
there something else on this furnace circuit? By code there cannot be
- but we don't know know this to be the case - or what is on the
circuit if there is.