Deif GPC-3 - Setup of Step-Down Transformer and Measurement Transformer

4.20.5 Setup of step-down transformer and measurement transformer
If the HV side of the transformer has a voltage level higher than 690 V AC, it will be necessary with measure-
ment transformers. In this example, the HV side is 690 V, and therefore there is no need for a measurement
transformer. The step-down transformer can have a phase angle twist, which must be compensated for. The
setup of all the parameters can be done from the utility software, and will be explained by an example:
Controller
G
Busbar 400 V
Dy1
690/400 V
Current transformer
500/1 A
U
GEN
= 690 V
I
GEN
= 500 A
690 V AC
direct input
400 V
The transformer is a Dy1 step-down transformer, with nominal settings of 690/400 V.
The generator has a nominal voltage of 690 V, nominal current of 500 A and a nominal power of 480 kW.
There is no measurement transformer in this application, because the ML-2 is able to handle the voltage lev-
els directly.
The nominal voltage of the busbar (BB) is 400 V.
It is still required to set up current transformers. In this example, the current transformers have a nominal cur-
rent of 500/1 A.
Due to the fact that the step-down transformer is a Dy1, there will be a phase angle twist of +30 °.
GPC-3 DRH 4189340587 UK
Additional functions
DEIF A/S Page 92 of 122