I’ve got into a problem. I have to measure up to 380 volts, however I’ve only found on the market sensors that measure up to 220 volts. Also the emon devices don’t do that. So, any ideas?
IoTaWatt with Magnalab SPT-0375-600. You would remove the burden resistor on one of the input channels and plug the output of the Magnalab potential voltage transformer with a 3.5mm jack. The Magnalab goes for about $60. There’s a used one on eBay right now for $30.
Cool, thank u for the reply. Do u know any other one cheaper than this?
Yes. 380V to 12V transformers are commodity items in the HVAC and control market. IoTaWatt can accept most 12V inputs (depends on the low load voltage). Even if the voltage is a little too high, you would only need to add a 1K or 2K resistor in series with the secondary. This arrangement would go directly into the AC adapter plug with no modification of the IoTaWatt. These transformers typically cost about $20.
To measure a voltage of 380V AC, you could use a pair of 240V transformers with their primaries connected in series. Their combined output signal could be reduced in amplitude by using a pair of resistors so that a suitably small signal is presented to an emonTx or similar. After calibration, this method should allow reasonably accurate voltage monitoring to be done.