Omicron CP TD12 - Necessary measurements for three-winding transformers

OMICRON 45
Power transformers
5.6 Measurements on three-winding transformers
In IEEE Std. 62-1995
[1]
the test procedure is described for transformers with two and three windings.
Figure 5-12 shows the six measurements necessary for a three-winding transformer.
Figure 5-12: Three-winding transformer test according to IEEE 62-1995
A more detailed test procedure for 2- and three-winding transformers can be found in IEEE C57.12.90
[2]
1. ANSI Standard 62-1995: "IEEE Guide for Diagnostic Field testing of Electric Power Apparatus - Part 1: Oil Filled Power
Transformers, Regulators, and Reactors", IEEE New York, 1995
Table 5-8: The six necessary measurements
Test mode Energize Ground Guard UST Measure
GST High (HV) - Low, Tertiary - C
H
GST Low (LV) - Tertiary, High - C
L
GST Tertiary (TV) - High, Low - C
T
Supplementary Test for inter-winding insulations
UST High (HV) Tertiary (TV) - Low (LV) C
HL
UST Low (LV) High (HV) - Tertiary (TV) C
LT
UST Tertiary (TV) Low (LV) - High (HV) C
HT
2. IEEE Standard C57.12.90: "IEEE Standard Test Code for Liquid-Immersed Distribution, Power, and Regulating
Transformers", IEEE New York, 1995
Tertiary Low High
C
HT
C
LT
C
HL
C
T
C
L
C
H