"Robert Macy" <[email protected]
> schreef in bericht
I have one of those 1500 watt radiator style portable
electric heaters. Love it
However, rather than the built in thermostat turning
the unit OFF?ON every 15 min's or so, I was thinking
it would be more efficient to use an SCR dimmer control
to vary the amt or power it gets?
Does anyone know of an SCR control hefty enough to
handle this kind of resistive heating load??
|2nd attempt to post this reply!
|use a saturable core reactor, which is a variable inductor controlled
|by a DC current through a secondary winding. Used to be made by
|Northlake near Chicago.
|The inductor, with 0 DC current has maximum inductance and 'starves'
|the resistive load down to 5 to 10%, then at maximum DC current the
|inductor is saturated and almost all the power makes it to the load.
|The transfer/control is monotonic, but very weird. L vs Idc
|The DC control winding is wound in a 'fgirue eight' pattern so that
|one adds, one subtracts with no net to the other winding, but due to
|the high number of turns, saturates the core locally. Saturating
|locally interrupts the magnetic field lines and is like opening up a
|large air gap in the core, thus the inductance drops to nil.
|I prefer radiant heaters, too. You can point them at yourself and sit
|very comfortably like in front of a fireplace. Used to have hot air
|blast heating but that made the room's air excessively hot in order to
|be comfortable when sitting. Then when you get up and move around you
|swelter. Whereas with radiant heat, the air can stay cool so when you
|move around, you're still comfortable. But those contact closures!!!
|very irritating if you went to sleep, they get very loud.
|The variable inductor is great for controlling resistive loads
|especially in the 1kW to 10kW ranges. ...you can actually make your
|own if you want.
Interesting solution though to me it looks like an overkill in space, weight
and cost. Modern electronics might not be that interesting but are very