Flex Add-on Sensors stray induced current

Technical Questions
#1

I was wrong in the assumption that my Dishwasher Flex sensor was getting induced current from other circuits.

I believe that the Flex Sensor does not work properly when there is no load in the circuit being detected. The Sense microprocessor keeps reminding me, that the circuit is in “Standby” and the circuit “Turned Off” and then it has been in "Standby for xx minutes and now Off.

Please look at this condition with no-load on a flex sensor circuit in a energized load panel. The circuit may be getting induced current from other bare wires in the load center.

#2

Hi @kraig.patterson - a few notes here.

My guess would be that your dishwasher has a digital display/internal component of some sort that draws small amounts of wattage while it’s in “Standby”. My washer machine is monitored via Flex Sensors and I see something similar.

For Dedicated Circuit / smart plug devices, you can customize what a device “standby” threshold is. We have some information and examples located here:

Along with more information on how to set-up device standby threshold:

If you can rule both of the suggestions above out, I’d write into support@sense.com just so they can take a look on our end and make sure they we’re getting accurate signal readings from your flex sensors (or if anything looks off in general.)

#3

Justin, I have disconnected the hot wire at the dishwasher and the flex sensor (Dishwasher) alarms still come in. There is no other device on the load side of the circuit breaker.

I believe either the Flex sensors has a problem with no-load in a hot load center.

#4

Can you share a screenshot of the device in your Sense app and let me know the amount of wattage that was showing when the dishwasher was off at the breaker?

#5

Attached is a screen shot of the sense default window. The dishwasher is still disconnected at the device

Screenshot 2021-02-04 135633.jpg
Screenshot 2021-02-04 135633.jpg1283×837 111 KB

#6

I’m seeing a similar pattern of transition alerts between Standby and Off with a couple of my smartplugs (HS110 and HS300) here.

If I look carefully at the device timeline for my Washer (on an HS110), when I look closely at an alert like this

IMG_0183
IMG_01831170×296 55.2 KB

I find that there is typically a short 1W bump, like below, that has precipitated the alerts.

IMG_0182.PNG
IMG_0182.PNG2532×1170 81.5 KB

Here’s the same view of that “bump” from the raw 4 second sampling data from the same HS110 that Sense is getting its data from. A detailed vie (17:20 = 5:20PM)

Tight
Tight806×580 22.7 KB

And a broader view over time.

Wide
Wide806×580 33.6 KB

I can see how some kind of moving average (smoothing) of the data together with rounding could trigger the brief bump to 1W that caused the Off to Standby transition and subsequent Standby to Off.

1 Like
#7

Couple more screen shots.

Flex Sensor Issue 1.jpg
Flex Sensor Issue 1.jpg565×615 36.3 KB

Screenshot 2021-02-04 140841.jpg
Screenshot 2021-02-04 140841.jpg1120×786 92.7 KB

#8

Since we started

image001.png
image001.png307×576 15.7 KB

#10

Hm, not too sure why they’d be picking up anything here. You may also just want to try re-orienting your Flex Sensors per the instructions in the installation guide here:

It’s a good idea for you to reach out to Support (support@sense.com) so they can look at more granular data for your device than we have access to here and advise you on next steps.

#11

Justin – I swapped the flex sensors with each other. The problem stayed with the disconnected dishwasher.

#12

I am see those same spikes, up to 1500 watts as an instantaneous spike on a disconnected circuit. I swapped the sensors and I see the same.

1 Like
#13

The web-based version (home.sense.com) does not have the Power Meter for devices on either Edge or Chrome. Screen shots are harder to provide.

1 Like
#14

Yes, understand it is harder to get the screenshots from the phone/tablet Sense app over to to here. But it would be interesting to see the 1500W instantaneous spikes. That means one of two things:

  1. The CT / Sense is picking up a bizarre spike for some reasons related to it’s placement in the box of that specific Sense channel.

  2. You have something else wired into that dishwasher circuit.

#15

I also have this issue with both flex CTs and smartplug loads. Nuisance alerts when the device transitions between “off” and “standby” due to some very minute change in usage that’s below the standby threshold. It’s very annoying.

1 Like
#16

I placed the Flex Sensor on a very lightly loaded breaker (2 watts) just to test whether the spikes would disappear on the sensor that was going into to Standby multiple times an hour.

The Garage sense bubble was in Standby because it was under the threshold, but the spikes disappear and it has maintained monitoring the circuit varying the 2 watt.

I firmly believe that the Flex sensors has a issue working on a circuit that has no-load.

#17

Good careful analysis. How often did those 1500W spikes show up on the unloaded circuit ? Was there any baseline low level power ? And was that CT on an unloaded line or a line with an extremely high impedance to neutral. I would suggest that you contact support@sense.com so they can assess what they are seeing on their end.

For me, both my CTs used for DCM are on one of the 240V hot lines for each device. The one on my floor heating subpanel baselines at 7W (powers 4 or 5 thermostats). But the one on my Tesla HPWC (High Power Wall Connector) drops to true zero most of the time when a car is not connected (the charger is actually built into the car - it really is a just a connector). I believe that this wall connector would be very similar to a dishwasher in terms of a high impedance load. HPWC with no car attached below.

IMG_0393.PNG
IMG_0393.PNG2224×1668 111 KB

#18

The spikes would occur every 10 minutes for a rash of 24 or so, then quiet down.

I have several WeMo plugs (I schedule a two hour open and close so they don’t report as “Always On”)that drop to zero and their bubbles or circuits don’t flutter and get spikes like the Flex Sensors do.

I think it’s a engineering issue that needs to be looked at.

#19

Thanks for your info… My 2c - if you want it investigated, you’ll have to request via support@sense.com. They won’t go poking into your personal data without a specific request and permission from you.

#20

I sent a request in a couple days ago. Haven’t heard from them

#21

I’ll look into your support ticket - if there’s an issue with the Flex Sensors, Support will be able to replace them for you.