Calculating the transformer winding capacitance temperature coefficient involves understanding the variation of capacitance with temperature. Capacitance is affected by temperature changes due to factors like thermal expansion and changes in dielectric properties.
To calculate the transformer winding capacitance temperature coefficient, you'll need the following information:
Initial capacitance (C0): The capacitance value at a reference temperature (usually specified by the manufacturer).
Final capacitance (Ct): The capacitance value at the target temperature.
Reference temperature (T0): The temperature at which the initial capacitance (C0) is measured.
Target temperature (Tt): The temperature at which the final capacitance (Ct) is measured.
The formula to calculate the temperature coefficient (TC) of capacitance is as follows:
=
−
0
0
⋅
(
−
0
)
×
1
0
6
TC=
C0⋅(Tt−T0)
Ct−C0
×10
6
Where:
TC is the capacitance temperature coefficient in parts per million per degree Celsius (ppm/°C).
Ct is the capacitance value at the target temperature (Tt).
C0 is the capacitance value at the reference temperature (T0).
(Tt - T0) is the temperature difference between the target and reference temperatures.
Here's a step-by-step guide to calculating the temperature coefficient:
Step 1: Measure Capacitance at Reference Temperature (T0)
Measure the capacitance of the transformer winding at the reference temperature (T0) specified by the manufacturer or chosen as the starting point.
Step 2: Measure Capacitance at Target Temperature (Tt)
Measure the capacitance of the transformer winding at the target temperature (Tt) for which you want to calculate the temperature coefficient.
Step 3: Calculate the Temperature Coefficient (TC)
Use the formula mentioned above to calculate the temperature coefficient (TC) of capacitance in ppm/°C.
Keep in mind that the temperature coefficient of capacitance is usually a small value and can be both positive and negative, depending on the materials used and their temperature characteristics. A positive temperature coefficient indicates that capacitance increases with temperature, while a negative coefficient indicates that capacitance decreases with temperature.
Please note that the accuracy of this calculation depends on the precision of the capacitance measurements and the assumptions made about the linearity of capacitance variation with temperature in the temperature range of interest. Additionally, some transformers may have a manufacturer-provided temperature coefficient value, which you can directly use instead of calculating it yourself.