Micro Air
Hi, just looking for input from people that have them on their effectiveness. I am thinking of getting a portable genny for the 5th wheel for those times that I need an AC and don't have power. I ha...
Forum Discussion
micro air vs. autotransformer:
the purpose of the micro air is to reduce PEAK starting current (locked rotor amps) so that non ideal voltage sources (typical small generator) that have limited max current output to START a AC unit. It does nothing to increase voltage once started.
Autotransformer:
bump up a low voltage source to a higher voltage to keep voltage within expected operating range.
So. If your using a "ideal" voltage source, most utility lines that can easily supply 3x or more the breaker rated current on a short term basis, the micro air really isn't needed.
But if your line voltage sags, then the autotransformer is solution.
Now I suspect, but can't verify, that what pianotuner is seeing with the micro air and autotransformer is this, The auto transformer probably has hysteresis, it will cut in at a low voltage and KEEP it in at a given level EVEN if the input voltage rises somewhat above the cut in voltage. So what may be happening is w/o the micro air, voltage sags enough to cut in the autotransformer but it doesn't rise enough to cut it out completely and continues to do it's intended job,
Now add the micro air, Now input voltage never drops enough to get the autotransformer to cut in, since the current draw is low enough to not cause a big enough sag in input voltage, so the voltage remains at the very low end,
so.... in this case the micro air (a) isn't needed to start the AC anyway and (b) then voltage remains low,
If one takes the autotransformer out of the circuit and starts the AC I suspect the line voltage then would be back to the 107 or whatever it is with the micro air, Micro air shouldn't reduce the input current draw once the compressor is running by any noticeable amount, it only reduces starting current,
the purpose of the micro air is to reduce PEAK starting current (locked rotor amps) so that non ideal voltage sources (typical small generator) that have limited max current output to START a AC unit. It does nothing to increase voltage once started.
Autotransformer:
bump up a low voltage source to a higher voltage to keep voltage within expected operating range.
So. If your using a "ideal" voltage source, most utility lines that can easily supply 3x or more the breaker rated current on a short term basis, the micro air really isn't needed.
But if your line voltage sags, then the autotransformer is solution.
Now I suspect, but can't verify, that what pianotuner is seeing with the micro air and autotransformer is this, The auto transformer probably has hysteresis, it will cut in at a low voltage and KEEP it in at a given level EVEN if the input voltage rises somewhat above the cut in voltage. So what may be happening is w/o the micro air, voltage sags enough to cut in the autotransformer but it doesn't rise enough to cut it out completely and continues to do it's intended job,
Now add the micro air, Now input voltage never drops enough to get the autotransformer to cut in, since the current draw is low enough to not cause a big enough sag in input voltage, so the voltage remains at the very low end,
so.... in this case the micro air (a) isn't needed to start the AC anyway and (b) then voltage remains low,
If one takes the autotransformer out of the circuit and starts the AC I suspect the line voltage then would be back to the 107 or whatever it is with the micro air, Micro air shouldn't reduce the input current draw once the compressor is running by any noticeable amount, it only reduces starting current,
