Questions & Answers > 3wire 12Kv distribution system metered with a 9S

We have 12Kv 3 wire distribution sys. Engineering wants better PQ on each phase. So here is the question. What is the problem with metering the 3 wire system with 9S meter using 3 CTs & 3 VTs with VT secondaries starred much like a 4 wire system. VTs wired Delta on the primary and Wye on the secondary. Is there a phase shift? If so can it be corrected with reactiformer? Has this ever been done?

April 5, 2010 | Unregistered CommenterGary O'Connell

If you measure and combine the instantaneous power phasors on the three wires of the three wire system, the result will be zero. Blondel's theorem talks abour n-1 metering elements on a system of n conductors. Another way of phrasing this is, the phasoral sum of the instantaneous powers on n-1 conductors in a system of n conductors is equal to and opposite the power phasor on the remaning conductor.

May 12, 2010 | Unregistered Commenterdave from tillamook