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var sign for inductive loads

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

http://iac.cl/descargas/manuales/schneider/PM500.pdf

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.   

"The more the universe seems comprehensible, the more it also seems pointless." -- Steven Weinberg

RE: var sign for inductive loads

(OP)
Thanks dpc.

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

David,

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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If we learn from our mistakes I'm getting a great education!
 

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.

 

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