50 kVA Transformer Thermal Time Constant 2

[W.H. Lazenby]

Does anyone know the thermal time constant of a 50 kVA transformer?

 

[7anoter4]

You may calculate it according to IEEE Std C57.96-1999 6.2.2 Calculation of transient temperature:
C = 0.106 × weight of copper winding, or C = 0.033 × weight of core and copper windings from the nameplate. C = 0.260 × weight of aluminum windings, or C = 0.044 × weight of core and aluminum coils from the nameplate.
or according to IEC 60076-12/2008 Part 5.10.2 Time constant calculation method

 

[7anoter4]

See attached file too:

 

[7anoter4]

For oil-filled transformer see IEC 60076-2

 

[prc]

There are two-time constants - oil temperature time constant for heating (1-3 hours) and winding temperature time constant 5-8 minutes)