Problem with App Circuit Readings

[billinghamn]

Just installed a Vue 2 in my garage CU (UK based) as a test, prior to installing a second Vue 2 in my house.  The garage covers 5 circuits (relating to all of the breakers visible in the CU).  I have two problems:

1. When there is minimal load going through the CU (170w or so), there’s a Balance (in the app) appearing of between 10w and 25w for some reason.  When there is a significant load going through the CU (4,500w or so), this drops to between 1w and 15w.
2. All of the 5 circuits remain consistent across each second time interval (in the app), other than one.  One consistently reports 6w or 7w and then reports 0w for a few seconds, before it reappears at 6w or 7w.  I wondered whether this was due to having a faulty CT clamp, so I have switched the CT clamp, but there’s no change in its behaviour.  This circuit feeds sockets (a UK ring main) but there’s not a variable load plugged in (which might explain why it jumps from 0w to 6w/7w from time to time).

I accept that it’s (perhaps) unrealistic to expect that the Balance will be 0w at all times, but I would expect it to be a very small figure (in w), rather than anything up to 25w.

For clarity:

• I have checked that the CT clamps have been installed the correct way around.
• For my two ring main circuits with two cables feeding into the hot side of their breakers, I have placed the CT clamp around both cables (as advised by another UK user).

Any thoughts on why I see these two problems?

[djwakelee]

I believe I can explain both things you are seeing, and I see this here in the US also.

This is pretty typical for circuits that have very light loading, less than 10W.  With my setup of 2 Vue 2’s and 32 total monitored circuits, when the load on a circuit is less than like 5W, the software blanks it out to zero.  When it is above that (like 5-8W), it seems to alternate between showing the power and zero.  At about 10W, it is stable.  Sounds like you see about the same thing.

Emporia appears to be trying to blank out the noise which is present within the system.  If this were to be shown, it would appear as false power readings on the lightly loaded circuits.  But conversely, doing this blanking results in inaccuracy (missed circuit power) at lower power with real loads.  It says somewhere in one of the FAQ’s or in an old post that they do indeed do this, and a bit differently Vue 1 vs. Vue 2.

The balance is comparing the mains draw vs. the sum of the circuit clamps. But because some of those circuit clamps could actually have some small power consumption (say a single 5V 1A AC/DC adapter) and that isn’t shown on the circuit because it is forced to be zero – and the balance looks a bit higher than you’d expect.  In reality, there is power consumption on some of your circuits which are falsely showing ‘zero’, and that is why things seem a bit odd.

 

 

 

 

[billinghamn]

That’s really helpful – many thanks for explaining.

• This reply was modified 2 years, 8 months ago by billinghamn.

[Author]

Posts