Watt Meter Wattage Draw question
Watt Meter Wattage Draw question
(OP)
I've been messing around with a watt meter at work by measuring various plug loads such as the fan I used at my desk. Well i took the voltage and the amperage that was drawn by the fan, which was measured by the watt meter and multiplied them to get a power use which ended up being 42 watts. Amperage was .357 and voltage was 118 which equals the 42 watts. My question is when i change the watt meter to measure the power draw it tells me 22 watts why am I off by a factor of 2 ?






RE: Watt Meter Wattage Draw question
Keith Cress
kcress - http://www.flaminsystems.com
RE: Watt Meter Wattage Draw question
RE: Watt Meter Wattage Draw question
(OP)
1. Your desk fan is connected to an [ac single-phase source].
2. For an [ac single-phase load], power = voltage x current x power-factor x efficiency ....(W).
Where the unit of power in W, voltage in V, current in A; power-factor and efficiency are [ratios (without unit) with values not
exceeding 1 (respectively)].
3. In your case, the power consumption is 22 Watt; where the value or the [product of power-factor x efficiency] is around 0.5, which is the reciprocal of 2.
I hope the above is helpful to you
RE: Watt Meter Wattage Draw question