Talk:Blondel's theorem
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Single phase meter caption
[edit]I have corrected the caption to this photo. The IP edit was correct for this style of meter. A 3W 1Ph meter is called 1.5 element as it contains two half turn current coils and only one 240volt potential coils. Thus one full element and another half as one current coil does not have a matching pot. coil. Note the nameplate indicates 240 volts? This is never a system voltage on meters. It doesn't know what system it will be used on but only it's own coil ratings. Two pot. coils would have no other connection without being in parallel. The meter measures E x (I1+I2)/2. Since each phase is measured at half it's current and twice it's line to neutral voltage all is metered correctly by old standards of accuracy and Blondel's theorem. This is not a good meter for this article cannot meter accurately on any 3 phase 3 wire system accurately due to the 120 degree potentials. That takes two complete elements. A 25% error would be encountered on line-neutral loads. 174.118.142.187 (talk) 00:03, 11 December 2012 (UTC)
- According to the maker's literature, it's a single-phase meter; it doesn't need the potential coil connected to the neutral, and the maker's literature shows it connected on 120-240 "split phase" systems. (I bet the meter on my house right now is only a 3 wire meter...but it's dark and -25 C as I type, so OR will have to wait.) --Wtshymanski (talk) 06:56, 2 January 2013 (UTC)
- The meter configuration is a shortcut from a full two element meter. Yes it meters accurately but, ,it does not meet the requirments of Blondell's theorum. It does not in have two elements and the potential coils of do NOT connect to the unmetered common conductor, as required by this theorum. Since it is another method of metering a single phase loads, does not obviously use Blondell's theorum to make it work (equivalent only), and is confusing non-meterology people readers and editors I am removing it. We need another type of meter for the example that actually and clearly applies Blondell's theorum. 174.118.142.187 (talk) 19:18, 2 January 2013 (UTC)