Testing A Three-Phase Transformer - AEMC 8505 Quick Start Manual

2.2.3 Testing a Three-Phase Transformer

Three-phase transformers can have many different configurations.
The two most common configurations are Y (wye), with each phase
connected to neutral; and Delta (Δ), with each phase connected to the
other two phases.
The following diagram shows the typical three-phase transformer access
points for primary Y (left) and secondary Y (right) configurations.
H2 X2
H0 X0
H1 H3 X1 X3
Primary Y Secondary Y
For Y configurations, you must measure from each phase to neutral and
from each phase to other phases.
A typical Delta configuration for a three-phase transformer is shown
below:
H2 X2
H1 H3 X1 X3
Primary Delta (∆) Secondary Delta (∆)
For Delta configurations, you must measure from each phase to other
phases. Note that in this configuration, if one coil is open, the Model
8505 can still perform tests because the other two coils may be intact
and there is a complete pathway.
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Quick Tester Model 8505