A vector group such as Dyn11 or YNd1 gives the high-voltage connection in capitals (D for delta, Y for star), the low-voltage connection in lower case, N or n where a neutral is brought out, and a clock number for the phase shift in 30 degree steps. Dyn11 is a delta primary and star secondary with neutral, the secondary leading the primary by 30 degrees. Transformers can only be paralleled if their vector groups give the same phase shift.
New unit is Dyn1 and the old one is Dyn11, they won't parallel on the LV side as connected, check the vector group before you order.
Also heard as
- vector group designation
- connection symbol
Related terms
Differential protection
Scheme that compares current entering and leaving a protected zone and trips when the two disagree.
Earthing system
Arrangement describing how a supply's neutral and an installation's exposed metalwork are connected to earth.
OLTC
On-load tap changer: a transformer switch that changes the turns ratio under load to regulate voltage.