I have a Brennenstuhl PM 230 UK-power-socket current meter that tells me how much power is being used on the appliance plugged into it.
It's a nice piece of equipment, but I'm wondering if there are any multimeter/electronics/physics gurus who can tell me: how likely is it that the claimed power usage in Watts is a useful figure.
I.e. what are the chances of this device (relatively cheap) giving me a measurement of 'true power' rather than 'apparrent power' (simply IxV)?
The device claims to offer a measurement of 'cos thi', which it refers to as the power factor. But I've seen physics/electronics sites that criticise meters that bandy-about the phrase 'cos phi' without actually defining what is actually being measured.
So: cheapo socket voltmeter, or true power reading? Anyone know about this device specifically?