ABB REG670 Applications Manual page 664

Section 17
Monitoring
658
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:
• IEC: Transformer parameters like constants, winding and oil exponents will be
taken from IEC 60076-7 standard for temperature calculations.
• IEEE: Transformer parameters like constants, winding and oil exponents will be
taken from IEEE C57.96-1995 standard for temperature calculations.
CurrSelectMode: This setting is used to select the current determining method which
is used for the load factor calculation. The function takes phase currents of each
winding as input. From each winding, only one phase current is considered for load
factor calculation. The options are:
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
1MRK 502 071-UEN -
Application manual