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Configuring a Proper Connection for a 3 Phase Open
Delta Question: What is the proper connection for a 3
phase open delta?
Answer
from Mike Leno:
The open Delta Configuration is
usually used in remote well pump locations. Two phase legs and a MGN
(multi-grounded-neutral) are connected in open Delta. This provides 240VAC
three phase for a pump or motor. This is a cost savings measure since there is
one less power line and one less transformer in the system.
You can use a single phase three
wire setup table or a Wye table to meter this circuit. You would place CTs on
the two ungrounded lines (L1, L2). Since this is a three element system, a two
CT method should adhere to Blondel's Theorem and meter correctly. If you use a
WYE method with three CTs, it would just meter zero on one of the channels, but
the system totals should be correct. Make sure that your CTs match the correct
voltage leads of the logger (CH1/L1, CH2/L2). |