Ring core CTs

I'm looking to monitor many 15 to 40 Amp circuits.  Brultech sells what they call Micro-CTs  (ring core, not split core) for a reasonable price but their shipping cost is a little steep.

Does anyone know who makes the Micro-CTs they sell or another source for them? http://www.brultech.com/home/store/category.php?id_category=38

For the 0-20Amp range I saw a post from calypso_rae who's using a TA17L-04 that's available on ebay.  Anybody know of any other alternatives?


Robert Wall's picture

Re: Ring core CTs

Just a caveat about the VA rating. Many small CTs don't have an adequate output power for the voltage required by the emonTx / emonTx Shield, and you need to derate them. It's something you need to check before you order. The hard part is they almost never state it directly, and you have dig to find enough information to calculate it. For example, the 40 A one: "Max continuous primary current Output: 26.23mA @ 40A" but nowhere does it state what the maximum burden voltage can be at that current, so you need to ask them if it's capable of 1.1 V rms (for the emonTx) or 1.75 V rms (for the emonTx Shield).

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