K
Knobhead
Found this a DNO document Dated 2011
Standard transformers will be designed to have an impedance of 4.75%
(5% on 1500kVA transformers) on rating at nominal tap, will be connected
Dyn 11, will have a ratio 11000/433/250V with a tapping range of ± 5% in
2.5% taps. The transformer will have a Basic Impulse Level (BIL) of 75kV.
The DNO’s won’t change, they can’t without major upheaval. The networks overloaded as it is. Drop the voltage, the current rises on just about everything baring lighting and a lot of that won’t be happy. Interconnects between sections of the LV network would be unusable.
I tried dropping the voltage on an 80MVA system to give 400/230V. Soon put it back to 433/250V nothing but trouble.
Standard transformers will be designed to have an impedance of 4.75%
(5% on 1500kVA transformers) on rating at nominal tap, will be connected
Dyn 11, will have a ratio 11000/433/250V with a tapping range of ± 5% in
2.5% taps. The transformer will have a Basic Impulse Level (BIL) of 75kV.
The DNO’s won’t change, they can’t without major upheaval. The networks overloaded as it is. Drop the voltage, the current rises on just about everything baring lighting and a lot of that won’t be happy. Interconnects between sections of the LV network would be unusable.
I tried dropping the voltage on an 80MVA system to give 400/230V. Soon put it back to 433/250V nothing but trouble.
