ABB REC670 Applications Manual page 557

1MRK 511 401-UUS A
Bay control REC670 2.2 ANSI
Application manual
• Three Phase Trafo: The function considers the given transformer as three phase
transformer.
• Single Phase Trafo: The function considers the given transformer as single phase
transformer.
Based on the settings TrafoRating and TrafoType, transformer parameters are selected
for temperature calculations. Both IEEE and IEC standards defines the transformer
parameters based on three categories of transformer rating.
In the case of three phase transformers:
• If the transformer rating is less than 2.5 MVA, the function considers this as a
distribution transformer.
• If the transformer rating is less than 100 MVA, it is considered as a medium power
transformer.
• If the transformer rating is above 100 MVA, it is considered as a larger power
transformer.
In the case of single phase transformers:
• If the transformer rating is less than 0.833 MVA, the function considers this as a
distribution transformer.
• If the transformer rating is less than 33.3 MVA, it is considered as a medium
power transformer.
• If the transformer rating is above 33.3 MVA, it is considered as a larger power
transformer.
NoOfWindings: This setting is used to set the number of windings in the transformer.
The options are :
• Three winding: The function considers the given transformer as three winding
transformer.
• Two winding: The function considers the given transformer as two winding
transformer.
Based on the setting NoOfWindings, hot spot temperature of the winding 3 is either
calculated or assigned as zero.
ConstSelection: This setting is used to select the transformer parameters taken either
from IEC 60076-7 standard or IEEE C57.96-1995 standard. The options are:
Section 17
Monitoring
551