Current Sensing Module


(Dave Schierenbeck) #1

Has anyone seen, or does anyone have any ideas on how to make a module that will sense current, and let ST know the device is running, amount of power being used?

Here is my concept/issue: I have a gas dryer, that has an auxiliary fan in the exhaust duct, since it is such a long run. The problem is the pressure switch on the fan that is supposed to run the fan ONLY when the dryer runs, does not work very well, so the fan run constantly in the winter, even when the dryer is not running.

What I want is a way to “sense” that the dryer is running, and then “turn on” the auxiliary fan power with ST. The turn on/off is easy, but I need a module that a 120VAC appliance can plug into, that will tell ST if the device is on or off, or can sense the current flow thru it.

I’ve got to believe there are ton of other uses for such a thing. Something you can plug an appliance in to, and have it output to ST the amount of current it is drawing. Thus, you could tell if something is running or not, or you could monitor power usage throughout your house.

I’m not a EE, so the electronics thing is a mystery to me.

Any ideas/suggestions?

Thanks,

Dave


#2

#3

Just a quick a dirty app on how you might monitor the outlet for power consumption

preferences {
	section("Select Power Monitor"){
		input "sensor1", "capability.powerMeter"
	}
	section("System Variables"){
		input "minimumWattage", "decimal", title: "Minimum running wattage", required: false, defaultValue: 50
		}
}

def installed() {
	log.debug "Installed with settings: ${settings}"
	initialize()
}

def updated() {
	log.debug "Updated with settings: ${settings}"
	unsubscribe()
	initialize()
}

def initialize() {
	subscribe(sensor1, "power", powerInputHandler)
}


def powerInputHandler(evt) { // called when the outlet sense power consumption (or power change)
	def latestPower = sensor1.currentValue("power")
	log.trace "Power: ${latestPower}W   "
	if (latestPower > minimumWattage) {
		log.trace "The dryer is on"
	}

}

(Matt) #4

or


(Dave Schierenbeck) #5

So, this outlet will allow me to “sense” the power consumption of the dryer, and thus tell ST the dryer is running?

I assumed that it was only an on/off relay to turn an appliance on/off with ST?

Can I then use the “The dryer is on” event, to trigger another ST Outlet to turn on or off?

Sorry - I’m new to all this.

Dave


#6

Yup. that is no problem. Below is a modified portion of the code I posted earlier

preferences {
	section("Select Power Monitor"){
		input "sensor1", "capability.powerMeter"
	}
	section("Select Dryer Fan"){
		input "dryerFan", "capability.switch"
	}
	section("System Variables"){
		input "minimumWattage", "decimal", title: "Minimum running wattage", required: false, defaultValue: 50
		}
}


def powerInputHandler(evt) { // called when the outlet sense power consumption (or power change)
	def latestPower = sensor1.currentValue("power")
	log.trace "Power: ${latestPower}W   "
	if (latestPower > minimumWattage) {
		log.trace "The dryer is on"
       dryerFan.on()
	}

}

The above is hardly a working app but the ideas are there. If you dont understand the code and such app does not exist, dont hestitate to ask for further help on this forum. The solution is quite simple given the right devices are in place :slight_smile:


#7

Not sure that would work for what he want to do. He needs to sense to power on one and only one specific outlet/module and based on the reading turn on another switch/module.


(Matt) #8

yeah but that 110V module wont work I dont think. Most driers are 220. Tehy have the 2 legs and all the energy monitor is is an amp clamp so it should be able to attach where the cable connects to the drier


#9

Now I am not sure we have all the info. Just re-read the initial post. The dryer is gas operated but I think there is still power involved. He mentioned the need to a 120VAC outlet. Not sure if that was for the dryer or the fan?? :confused:

If the dryer (without the fan) does not draw power… All bets are off :smile:


(Matt) #10

and then there is that :slight_smile:


(Dave Schierenbeck) #11

The Dryer is GAS, so I’m just monitoring the 110V portion that runs the motor, etc. NOT 220V

The fan is also 120V, and that is what I want to turn on/off.

I’m thinking I can use the Aeon Labs DSC06106 smart energy switch I found on Amazon??

(I don’t know how to paste a picture like was done above)

Dave


#12

Glue/tape a z-wave/zigbee temperature sensor to the dryer exhaust. When the temp rises above a set parameter, turn on fan :smile:


(Dave Schierenbeck) #13

Here is the link to amazon


(Allan) #14

Yes, you can use that to detect the power usage of the dryer and when it’s above a certain threshold you could use a second one to turn on and off your exhaust. At least thats how I understand your issue. Not bad for $60 total.

-Allan


(Dave Schierenbeck) #15

I ordered 2 and we’ll see what happens.

Do I need to write custom code to get this to work, or is there a SmartApp that will work for this?

Never did any of the programming yet . . .

Dave


(Matt) #16

rule machine will do it for you.

if switch 1 current >= X amount then turn on switch 2


#17

Like Matt said… Rule Machine app

If that doesnt do it for you, let me know. Easy app to write…


(Dave Schierenbeck) #18

OK, so I got the current sensor, and I’m playing around with Rule Machine.

Question: Can I change how frequently the Aeon power sensors get updated by the Hub? When I start the dryer, there seems to be a pretty significant lag before ST recognizes that the Power level is above my setpoint (10 in this case).

It seems like I have to refresh the sensor from the app manually to get rule machine to trigger the other switch on.

How can I make this automatically update the power coming from the Aeon sensor?

Thanks,

Dave


(Dave Schierenbeck) #19

I think I partially answered my question - the Pollster App.

If anyone has any better suggestions, please let me know.

Dave


(Matt) #20

look for Aeon HEMv2+ it lets you lower the poll to seconds