Polyphase meter connections 30 years after woodson

In 1928, w. c. Woodson announced his procedure for verifying instrument transformer connections to meters for 3-phase 3-wire services.1 The Woodson method has earned the reputation of being the most reliable and satisfactory practice for proving these connections. In 1928, the procedure had minor limitations. Since that time, the employment of 3-phase 4-wire distribution systems, the growing impracticability of reducing customer loads for connection testing to balanced 3-phase known impedances, and the increasing use of capacitors have caused difficulty both in proving internal meter connections and in estimating the load phasors needed for comparison with the Woodson phasors obtained at the meter test switch. There is no procedure that will signal a definite “no” or “yes” that meter test switch phasors correspond to load phasors. On the contrary, the matching of load and Woodson phasors is entrusted to human judgment, and errors are probable. On one utility system, 3 1/2 stator Woodson kits, used in proving over 1,500 complex metering installations, have given added but not complete insurance for verifying 4-wire Y systems. Thirty years of electrical growth and changes have increased the limitations to proving transformer-connected meter installations. In the meantime, there have been no adequate new or extended procedures to give required integrity in this area of metering.