ABB Relion 670 Series Applications Manual page 483

1MRK 511 401-UUS F
• 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
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:
Average : The average of all phase currents of winding is considered for calculation.
•
• Maximum : The maximum current out of the all phase currents is considered for calculation.
TempeUnitMode : This setting is used to select the temperature unit to be used for the function
interface. The options are:
°F : The temperature unit will be selected as °F. Since all calculation formulae needs
•
temperature values in °C, the temperature inputs are converted into °C for calculation. Once
the calculations are done, the outputs in °C are converted into °F.
• °C : The temperature unit will be selected as °C. All temperature inputs will be taken as they are
and the output is given in °C.
LOLSPTR (26/49HS) can work with (n-1) winding CT availability, that is, if the given transformer
has three windings and it has CTs only in two windings, then the function will calculate the missing
winding current based on voltage transformation ratio. Following settings are required to
calculate the winding current with available CT input:
AvailableCT : Availability of CT connection can be set by this setting. The options are:
Bay control REC670
Application manual
NoOfWindings , hot spot temperature of the winding 3 is either calculated or
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Section 17
Monitoring
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