6
TRT33A Designated Use
3
Designated Use
The Three-phase Transformer Turns Ratio Tester TRT33A is specially designed for turns ratio, phase
shift and excitation current measurement of power, distribution and instrument transformers.
The TRT33A generates single-phase and true three phase test voltage. When generating a single phase
excitation voltage, the TRT33A generates and outputs an excitation test voltage to the three transformer
primary windings, in turn. The induced voltage across the unloaded transformer winding is then
measured; the ratio of these voltages is calculated and shown on the display, for all three phases. Vector
groups measured with single phase test voltages are shown at the end of this Manual.
When generating true three phase voltage, the TRT33A generates and outputs a true three phase
excitation test voltage to the three transformer primary windings. The induced three phase voltage
across the unloaded transformer windings are measured and the transformer turns ratio is calculated.
Any other use of the TRT33A than the ones mentioned above is to be considered improper and will not
only invalidate all customer warranty claims but also exempt the manufacturer from its liability for repair
or exchange.
