Setup Of Step-Down Transformer And Measurement Transformer - Deif GPC-3 Designers Reference Handbook

GPC-3 DRH 4189340587 UK

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:
Busbar 400 V
Dy1
690/400 V
G
U
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 °.
DEIF A/S
Controller
690 V AC
direct input
Current transformer
500/1 A
= 690 V
GEN
I = 500 A
GEN
400 V
Additional functions
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