Substation Monitoring

Is anybody monitoring an outgoing way of a substation?
I have a 315a circuit that I want to monitor with 300mm2 XLPE
What I’m really after is what CTs people are using to fit around a cable of that size, also Id be looking at split core to avoid disconnecting the conductors.


Look at the “Use in N.America” page. There are many large c.t’s (mostly split-core) listed there.
(You’re allowed to look even though you’re from E. Anglia :grin: )

You’re likely to need to change the burden and the calibration, otherwise it should all work.
The bad news is, you’ll probably have to import the c.t’s. I don’t know of a UK manufacturer of split-core with a 50 mA or so secondary.

AFAIK, Howard Butler only do 5 A secondaries. You could do that, with the burden mounted external to the emonTx/emonPi.

If you’re looking for large split-core CTs, try Andy at Sibert UK ( ) he’s a guru when it comes to things like that, if it;s available he can source it. - He’s used to dealing with all sorts of cable sizes.
Rgds Gordon

TBH I have been struggling to find large enough CTs at the right price.
@Robert.Wall Can you confirm that the CTs need to be 1v? or can you use modern 0.33v CTs?


How about a Magnelab SCT-1250 or SCT-2000 with a 1 Volt output?

Manutech is Magnelab’s European distributor.

You can use a 0.333 V c.t, but then you’re using less than ⅓ of the available range of the ADC, so resolution - in form of performance at low currents, will suffer correspondingly. Effectively, you push the minimum current you can measure with any given accuracy up by a factor of 3.3. So best avoided if at all possible. (Unless of course this is not a concern. To most, it is.)