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clembo
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Homework Statement
An oil-filled transformer has a c.m.r. of 500 kVA which allows it to run continuously in an ambient of 35°C with an oil temperature rise of 50°C. The transformer has a time constant of 1.5. hours and the ratio of copper losses to iron losses at c.m.r. is 1.5:1.
After switch-on, the transformer supplies a load of 600 kVA for one hour and the load then rises to 750 kVA. Calculate the period of time that the transformer can supply this load without exceeding its rated maximum temperature. Sketch the heating curves for the two loads.[/B]
Homework Equations
The temperature rise of a transformer is given by the equation
[/B]
-t/τ
where
θ is the temperature rise at any time t,
θm is the final steady temperature,
τ is the heating time constant (determined by the heat capacity and efficiency of cooling).
The Attempt at a Solution
From the above equation I understand the temperature rise, final steady temperature and time constant. But what does anyone know what the "e" signifies. Any help on this question would be very appreciated. I can't find much information on this topic online.
Many thanks
Andy[/B]