ABB REC670 Applications Manual page 520

Section 17
Monitoring
514
OilTmConstMode: This setting is used to select the oil time constant mode of input
to the function. It has three options:
• Standard: Oil time constant is taken from the IEEE or IEC standard as selected
for the temperature calculations.
• User defined: Oil time constant is provided by the user through setting. The
value may be given by the transformer manufacturer.
• Calculated: Oil time constant is calculated by the function based on the
transformer parameters given by the user.
OilTimeConst: This setting is used to get the oil time constant from the user and
this will be used when OilTmConstMode setting is selected as User defined. Likely
it is between 1 and 3 hours.
AvgOilTmpRise: The top oil temperature is based on the average temperature rise
of the lumped mass. In the case of transformer, this would be the average oil
temperature. This setting is used to set the average oil temperature rise above
ambient temperature in K (Kelvin). This value should be obtained from the
manufacturer based on certified heat run test reports conducted at maximum rating
given in the name plate.
CoilCoreMass: This setting is used to set the transformer coil and core assembly
mass. This mass consists of all winding mass, core mass and paper mass of the
transformer.
OilMass: This setting is used to set the transformer oil mass. This mass consists of
free oil mass and oil insulation mass of the transformer.
TankMass: This setting is used to set the transformer tank mass. This mass is only
the tank and fittings that are in contact with heated oil.
LoadLoss: This setting is used to set the transformer load loss at rated condition.
TTLoadLoss: This setting is used to set the transformer load loss arrived from type
test.
NoloadLoss: This setting is used to set the transformer no-load loss.
TTNoloadLoss: This setting is used to set the transformer no-load loss arrived from
type test.
Winding time constant is the time for winding temperature to rise over the oil
temperature to reach 63.2% of the difference between the final rise and initial rise
during a load change. The winding time constant may be estimated from the
resistance cooling curve during thermal tests or calculated by the manufacturer
using mass of the conductor material. The function has the following settings
related to winding time constant.
WdgTmConstMode: This setting is used to select the winding time constant mode
of input to the function. It has three options:
1MRK 511 401-UEN A
GUID-BDD32D22-D1C2-47C2-9B4C-A055C847CCA2 v1
Bay control REC670 2.2 IEC
Application manual