emonTx AC power

When installing emonTx with AC power supply, does the location of the power socket affect the accuracy of the real power calculation at all? That's to say, is it OK to trail an extension cord from any socket without affecting results?

Robert Wall's picture

Re: emonTx AC power

Short answer - possibly!

The ac adapter both supplies operating power and measures the supply voltage. So if that voltage is not representative of the system voltage, it won't measure any sort of power (not just real) accurately. If it's fed through a long and thin extension cable and there's no other load on that cable, it should be OK, if there is another (substantial - but the definition of that depends on the cable size) load on that cable, then it won't be OK. Ideally, you should have it as close to the supply incomer as possible. If you know the load current on any particular length of cable, and you know the cable size, you can look up the volt drop in tables and calculate the error from that.

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