19
TRT33A Getting Started
5.2.2 Measurement on three-phase transformers
After all connections have been made, choose an appropriate transformer vector group in the
CONFIGURATION
menu. You can also select TRUE 3~ TEST if you want to test ratio by applying true
three-phase test voltage.
Available vector groups in this menu are listed in the Table 4.
Table 4:
Available vector group configurations
Configuration
Displacements
D-D, D-Z, D-Zn, Z-D, Zn-D, Y-Y, Y-Yn, Yn-Y, Yn-Yn
0-2-4-6-8-10
D-Y, D-Yn, Y-D, Y-Z, Y-Zn, Yn-D, Yn-Zn, Z-Y, Z-Yn, Zn-Y, Zn-Yn
1-3-5-7-9-11
If AVGD option is selected, the TRT33A will automatically detect vector group of transformer under test.
Press
UP/DOWN
to choose HV configuration. To confirm your selection press
ENTER
. After pressing
ENTER
, cursor will automatically go to the LV configuration position. Enter LV configuration and then
phase displacement number.
Note:
It is recommended to select TRUE 3~ TEST in cases when:
- the vector group of the transformer under test is not available,
- there are no regular conditions on the transformer side that TRT33A can detect vector group
correctly,
- the transformer under test has the windings distributed on different magnetic core legs,
- it is necessary to measure phase displacement of transformers with irregular vector groups like
phase shifting, rectifier, arc-furnace and traction transformers.
In such a way the TRT33A will perform the test with true three-phase voltage and show results.
Enter the nameplate voltages and press
ENTER
to confirm selection.
If the nameplate voltages are not entered, the TRT33A will perform a test and display the result, but it
will not calculate nor display turns ratio deviation.
The TRT33A generates single-phase and true three phase test voltage.
When generating a single-phase excitation voltage, the TRT33A supplies in turn single-phase excitation
test voltage to each of the three transformer primary windings. The induced voltages across each of the
corresponding unloaded transformer windings are then measured; the ratio of these voltages is
calculated and shown on the display. It is repeated for all three phases. Vector groups that can be
measured with single phase test voltage applications are shown at the end of this Manual.
Figure 5-16:
CONFIGURATION
menu
Figure 5-17:
The
NAME PLATE
voltage selection
