high voltage comperator / main line monitor
high voltage comperator / main line monitor
(OP)
Hi @all,
I'm looking for a bright idea to monitor the main line for zero voltage crossing, with the lowest possible power consumption. Does anyone have a hint with a current consumption <5µA (my application 230VAC 50HZ)?
Regards,
Andreas
I'm looking for a bright idea to monitor the main line for zero voltage crossing, with the lowest possible power consumption. Does anyone have a hint with a current consumption <5µA (my application 230VAC 50HZ)?
Regards,
Andreas





RE: high voltage comperator / main line monitor
Dan - Owner
http://www.Hi-TecDesigns.com
RE: high voltage comperator / main line monitor
RE: high voltage comperator / main line monitor
@macgyver:
Maybe a MOSFET with a very high Vgs would work, but I haven't seen such a device yet :(
@VF1BLL:
I don't want to waste energy, that's all.
Regards,
Andreas
RE: high voltage comperator / main line monitor
The 5 uA at 230 V - if that is what you meant - equals a little more than 1 milliwatt. I don't know if energy savings should start there. There are tens or hundreds of other savings you can do.
Anyhow, a capacitive coupling between 230 and your device will not draw any energy at all. Or very little. Then you can use your saved milliwatt to supply 3.3 V to a micro running at about 100 kHz where it doesn't draw more than perhaps 20 or 30 uA, which equals less than 100 uW.
Use the micro to adjust for the 90 degree phase shift in the capacitor.
You may need to put a low pass filter before the input pin to avoid HF hitting the pin directly. But that won't consume much power.
One question: Were you joking when you said that you wanted to save energy?
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: high voltage comperator / main line monitor
my application is a Staircase lighting time switches (hopefully) designed for low power. Right now the whole circuit consumes less then 50mW at 230VAC/50Hz. "Less then" should mean: I do not trust my meters which say 21mW (I'm waiting for a special standby power meter). The PIC micro is always running with 4MHz, maybe I can find a way to let the PIC goes to sleep mode. I'm not sure about that, because the PIC is filtering some annoying glitches and spikes from the main line to determine if someone pressed a switch or not.
So, to sense the main line consume ~5mW. Hugh, this is 25% of the overall power. Maybe, I'm not so wrong to start thinking about a better/other sense circuit.
I'm open for other ideas, therefore I will check the capacitor divider. Keep you informed.
Regards,
Andreas
RE: high voltage comperator / main line monitor
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: high voltage comperator / main line monitor
21mW = .021W = .000021KW
.000021KW x 24hrs per day x 365 days per year = .18KwH per year
.18KwH x .15$US per KwH = $0.03 per year.
You think it's worth improving on this?
RE: high voltage comperator / main line monitor
you are absolutely right. Improving from 0,7W down to <0,05W was a huge step. Now I'm looking to gain some more without increasing the BOM costs to much.
Regards,
Andreas
RE: high voltage comperator / main line monitor
Dan - Owner
http://www.Hi-TecDesigns.com