![\"\"](\"https:\/\/sense.com\/wp-content\/uploads\/2016\/02\/heatG0_I2004_h111_s0_yrange0_-400x178-1.png\")
<\/p>\nThe Sense home energy monitor detects devices by making use of the fact that every device plugged into your\u00a0home\u2019s electrical system has a signature approach to using electricity. Each of these electronic\u00a0signatures is unique (well, mostly anyway! There may be some cases where two devices use electricity in\u00a0EXACTLY the same way \u2014 but we are finding that is pretty rare).<\/p>\n
Let\u2019s say that your toaster, when on, is the only device in your home that uses 1200 watts. If that were\u00a0the case, Sense could just look for those occasions where your total electrical consumption increased by\u00a01200 watts, and determine that your toaster must have turned on. Then, when your consumption\u00a0decreased by 1200 watts, Sense could infer that the toaster must have turned off.<\/p>\n
If only device detection was that simple! You probably have many things in your home that use 1200\u00a0watts, and besides, most of the devices in your home are much more complicated than a toaster.<\/p>\n
And, it turns out, even the toaster isn\u2019t so straightforward \u2014the electrical resistance of the heating\u00a0element in your toaster increases with temperature. This means that as the toaster heats up, the\u00a0wattage it uses declines, so it’s using less than 1200 watts by the time it turns off.\u00a0And, to complicate\u00a0matters even further, if you make more toast right away, it uses less than 1200 watts when it starts back\u00a0up.<\/p>\n
So, how does Sense detect devices? We use more complex signals than just the overall wattage, and the\u00a0models we use are much more complex than just assuming things turn on and off in simple and\u00a0consistent ways.<\/p>\n
On the signal side, below we show a few waveforms of the current usage of a couple of different devices. Notice that\u00a0there are tons of details available in these waveforms, which go far beyond simple wattage calculations.<\/p>\n
The first image depicts the toaster, which is just a resistive load. This means (based on physics!) that the\u00a0current is exactly aligned with the voltage with a pretty stable relationship (it does get slightly smaller\u00a0over time based on the heat\/resistance relationship discussed above, but the effect is smaller than you\u00a0can see in this chart).<\/p>\n
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Next is an incandescent light bulb. It too is a resistive load, so the current follows the voltage as in the\u00a0toaster example. But the tungsten filament of the light bulb heats up far more quickly than a toaster, so\u00a0you can see the current usage dropping over just a few cycles (60 cycles per second, so drop happens\u00a0over 30-40ms).<\/p>\n
![\"\"](\"https:\/\/sense.com\/wp-content\/uploads\/2016\/02\/incG0_I2_h116_s4_yrange3700-400x178-1.png\")
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The last example is from a CFL light bulb. Notice there is a very sharp spike when it starts \u2013 this is caused\u00a0by a capacitor charging up to power the electronics. Once it starts, the current waveform looks quite\u00a0different than the nice voltage sine wave. This is very common for electronic devices in your home, and\u00a0the particular shape of these waveforms and how they startup are important device detection clues for\u00a0Sense.<\/p>\n
![\"\"](\"https:\/\/sense.com\/wp-content\/uploads\/2016\/02\/cflG0_I2011_h111_s2_yrange605_-400x178-1.png\")
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Those are just a few examples of one particular signal type. The tough job for our Sense data science\u00a0team is to map out the entire space of how signatures appear in the signals (and we look at many more\u00a0types of signals) and then to map those various signals to the complex devices in your home, which\u00a0consist of combinations of many elements all doing different things in these electrical signals. We have\u00a0just scratched the surface so far, but we are already starting to recognize many common devices in\u00a0homes. We have many more devices and features coming soon. Stay tuned!<\/p>\n","protected":false},"excerpt":{"rendered":"
The Sense home energy monitor detects devices by\u00a0identifying their unique electrical signals.<\/p>\n","protected":false},"featured_media":1085,"template":"","meta":{"_acf_changed":false,"om_disable_all_campaigns":false,"_relevanssi_hide_post":"","_relevanssi_hide_content":"","_relevanssi_pin_for_all":"","_relevanssi_pin_keywords":"","_relevanssi_unpin_keywords":"","_relevanssi_related_keywords":"","_relevanssi_related_include_ids":"","_relevanssi_related_exclude_ids":"","_relevanssi_related_no_append":"","_relevanssi_related_not_related":"","_relevanssi_related_posts":"1","_relevanssi_noindex_reason":"","footnotes":""},"consumer-blog-category":[22],"content-type":[13],"featured":[],"class_list":["post-1083","consumer-blog","type-consumer-blog","status-publish","has-post-thumbnail","hentry","consumer-blog-category-technology","content-type-article"],"acf":[],"yoast_head":"\n