Differential Current sensing for Home Assistant - Page 1
Forum section: electronics / projects

author: msknight
author_rank: Regular Contributor
timestamp: February 16, 2025, 05:47:42 am
content: I've got a 1cm diameter cable going from a switching unit to a 13A heating element. Obviously the element has an internal thermostat.I need to non-invasively detect when the thermostat is active. I've been trying to detect temperature changes at the bottom of the tank, but because the battery powered sensors aren't reporting back frequently enough, I can't get an accurate enough grip on things.I can't cut into the cable to isolate the live from neutral so I can't use the usual current sensing clamp.AI says that there are differential clamp sensors, but whenever I try and look them up, I get ICs. I'm hoping to find a sensor I can clamp around the cable and use to determine when the element is puling power, and hook it up to an ESP32 dev board to feed back to Home Assistant... or any other non-invasive ideas of doing this please.

author: Konkedout
author_rank: Frequent Contributor
timestamp: February 16, 2025, 07:00:12 am
content: Is this AC or DC current you are trying to sense?Just initiating some half-baked ideas, although "completely non-invasive" makes it more difficult. What are your size and price limits?1) Hall Effect Current Sensors2) Current transformer:https://www.digikey.com/en/products/filter/transformers/163?gad_source=1&gclid=CjwKCAiAk8G9BhA0EiwAOQxmfuPk_vPQ5yO4p3p5Y_LYAsTd-ruOT5xFI3D1Geeh6dRN1xYeR1yQ_hoC6P4QAvD_BwE&gclsrc=aw.ds&gclsrc=aw.ds&s=N4IgjCBcpgHAzFUBjKAzAhgGwM4FMAaEAeygG0R5YAGeANgE4QiraB2akAXSIAcAXKCADK-AE4BLAHYBzEAF8WAFiVIQqSJlyES5EACZ4bBgmYH61AKxMeIAUNGTZCogFp9ajeICuO0pApLbnlFECDoOygwPl4o6moQoA&utm_adgroup=Current%20Sense%20Transformers&utm_campaign=EN_Product_Transformers&utm_content=Current%20Sense%20Transformers&utm_id=go_cmp-1098425689_adg-54433146153_ad-632125739975_kwd-297243960362_dev-c_ext-_prd-_sig-CjwKCAiAk8G9BhA0EiwAOQxmfuPk_vPQ5yO4p3p5Y_LYAsTd-ruOT5xFI3D1Geeh6dRN1xYeR1yQ_hoC6P4QAvD_BwE&utm_medium=cpc&utm_source=google&utm_term=current%20sense%20transformer

author: msknight
author_rank: Regular Contributor
timestamp: February 16, 2025, 07:19:53 am
content: It's AC. Price limit, let's say £30 and see where we go.

author: ledtester
author_rank: Super Contributor
timestamp: February 16, 2025, 07:51:06 am
content: The SCT-013 current transformers are popular with DIYers.Just google: SCT-013 ESPHome.Available on Amazon / Ebay / Aliexpess and Digikey:https://www.digikey.com/en/products/filter/current-sense-transformers/163?s=N4IgTCBcDaIM4GMAuAGAjAZhAXQL5AIt seems some may have a burden resistor already installed (e.g. the 20A/1V) and others don't (e.g. the 100A/50mA version).

author: Terry Bites
author_rank: Super Contributor
timestamp: February 16, 2025, 08:46:41 am
content: No need to cut. You can get split core types.https://www.amazon.co.uk/PEACEFAIR-Electric-Split-core-Current-Transformer/dp/B077VKJ9GS?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&psc=1&smid=AUWJSTRS7M679&gQT=1Or, if you hate Satan Bezos buy it on Ali for £3.50.https://www.aliexpress.com/item/1005001898860908.html?spm=a2g0o.productlist.main.7.7c097cf4WuZqqN&algo_pvid=5e6e3505-227f-4991-8895-2f5b2cb51962&algo_exp_id=5e6e3505-227f-4991-8895-2f5b2cb51962-3&pdp_ext_f=%7B%22order%22%3A%221%22%2C%22eval%22%3A%221%22%7D&pdp_npi=4%40dis%21GBP%213.59%213.59%21%21%214.38%214.38%21%402103894417396954105745027e7749%2112000018055805509%21sea%21UK%213100120370%21X&curPageLogUid=dTdQYOv8zWJe&utparam-url=scene%3Asearch%7Cquery_from%3A

author: msknight
author_rank: Regular Contributor
timestamp: February 16, 2025, 09:13:18 am
content: Many thanks. I'll get some of those and look into that project.