1 Aug
2006
1 Aug
'06
11:42 a.m.
Hello Dwight
Please try at least one of two experiments. Either
actually measure
with an inductive load or do a simulation. For a transformer, zero
cross is the worst time to start.
Why? What do you expect to happen? At zero crossing there is no volts
and no current will flow. The current will start to increase as the
voltage increases and continue to do so until the next zero cross point.
Don't confuse steady state action with the first
cycle. The response
is not the same.
Agreed. At the first cycle there is no energy stored in the inductor so
switching it on at zero cross gives a circuit with no stored energy.
With an inductive load, this is at 90 degees, or peak
voltage. This is also the best time to turn it on.
If you turn on an inductor at peak voltage you will get a magnetization
offset that may take many cycles (approx LR) to decay. This gives a peak
current that is much greater that that from switching on at the zero
cross point and is clearly not the best point to turn it on.
Lee.