The temperature coefficient of resistance (TCR) for a transformer winding is a measure of how the resistance of the winding changes with temperature. It is an important parameter to consider in transformer design and operation, as it affects the performance and efficiency of the transformer. The temperature coefficient of resistance is typically represented by the symbol α (alpha) and is usually specified in units of ohms per degree Celsius (Ω/°C).
To calculate the transformer winding resistance temperature coefficient (TCR), you will need the following information:
Initial resistance at a reference temperature (usually at room temperature, 25°C or 20°C).
The resistance at another temperature (usually at a higher temperature where the measurement is taken).
The formula to calculate the temperature coefficient of resistance is given by:
α = (R2 - R1) / (R1 * (T2 - T1))
where:
α = Temperature coefficient of resistance (TCR) in Ω/°C
R1 = Initial resistance of the winding at temperature T1 in ohms
R2 = Resistance of the winding at temperature T2 in ohms
T1 = Initial temperature in Celsius
T2 = Temperature at which the resistance is measured in Celsius
Keep in mind that for accurate results, the temperature measurements should be in Celsius, and the resistance values should be in ohms. Additionally, it's essential to ensure the temperatures are consistent (both in Celsius or Kelvin) and that the resistance measurements are taken under the same conditions, considering factors like the winding's load and other environmental variables.
Note: The TCR of the winding material is generally given by the manufacturer and can vary depending on the type of winding wire or conductor used. It's crucial to consult the transformer's specifications or the manufacturer's datasheet to obtain the correct temperature coefficient of resistance for the winding material being used.