Energy use monitor, current transformers.

[John Rumm]

I was toying with building a multi channel current logger[1] that could be used to instrument multiple circuits.

Has anyone used one of these:

If so, do you have dimensions for it?

Just wondering how difficult it would be to get a bunch of them into a (reasonably large) CU. The only size I can see mentioned is for the hole is specced at 13mm across.

[1] Perhaps an Arduino mega, with ethernet/wifi to get loads of analogue inputs, and a capability to post logs every few seconds to a SQL database running elsewhere on the network. Capacity for 16 channels should cover all the circuits in both my CUs.

[Theo]

Not that one specifically, but I have (somewhere) one of these:

is 51 x 44.5 x 36.5 mm if you include the protrusions.

Judging by the scale of the jack plug I imagine that one is similar. ... ah, this has dimensions:

Probably doable. Or to tails outside.

Worth having a poke around Openenergymonitor as you might find they already make something to do what you want. Although 16 circuits might get a bit much.

Theo

[John Rumm]

Ah, well spotted, 57mm long by the looks of it - so quite large... might be able to get them in at an angle - and stagger the height of adjacent ones.

(I quite like that they are fully enclosed and are available in a voltage output version)

I wanted to be able to record each circuit in isolation really (or at least a number of them)...

Although one on the tails may be handy since I have one tall RCBO that there is unlikely to be space to clamp - so calculating that as total - others might do it.

Yup I did have a look at that - they did not have any off the shelf designs that did more than a small number of channels.

[Michael Chare]

You could try

[Sysadmin]

You could wind your own current pickup on individual wires and calibrate.

[Fredxx]

The ration of turns would be key. Hardly any need to calibrate. The concerns would be the core material, saturation, leakage and bandwidth to catch a spiky waveform.

[Clive Arthur]

You might find Rogowski coils convenient.

[Andy Burns]

They were one of the reasons given for the inaccurate readings by some meters in that Dutch university study a few years ago ...

Maybe the affected meters weren't using them properly?