var sign for inductive loads
var sign for inductive loads
(OP)
Consider a meter at a point where resistive and inductive loads and no sources are downstream of the meter. The meter in question is registering positive wattage. What is the sign of the reactive power? I ask because of one monitor manufacturer that is bucking the convention as I know it (positive). I have found some IEEE references to support my case. Is IEC any different? Can anyone provide an IEC reference? Thanks.






RE: var sign for inductive loads
I don't have a direct IEC reference, but take a look at page 32 of the link above (yes, it's slow). It shows a setting to switch the power factor sign convention from IEC to IEEE, so I'd guess one must be the opposite of the other.
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RE: var sign for inductive loads
Here's another manual with a better explanation on page 30: http://rep.mgeups.com/edg/edg/pmm/pm800man.pdf
Looks like they claim IEC and IEEE agree on the signs of watts and VArs and disagree on the sign of pf. I'm not sure what IEEE standard they might be referencing. pf is mathematically positive, the added sign is just a way to simply indicate lead or lag.
'later
RE: var sign for inductive loads
IEC 62053:23 2003 "Electricity Metering Equipment (AC) - Particular Requirements - Section 23: Static Meters for Reactive Energy (Classes 2 and 3)" contains a diagram showing essentially the same information as the 'IEC' half of Figure 4.2 in the Schneider manual. I'm not familiar with the 'IEEE' half of the diagram - never seen that convention before.
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RE: var sign for inductive loads
One reference is 10th edition of the Electrical Meterman's Handbook published by AEIC, but I think it skirts around PF signs.