Method of calculating effective power relating to capacitor, method of measuring effective power consumed by capacitor, capacitor selection method, calculation apparatus for calculating effective power relating to capacitor, and recording medium storing the calculation program therefor

A method of selecting a capacitor, comprising the steps of:

• obtaining an equilibrium temperature of the capacitor for each of a plurality of sine waves, and substituting a first capacitance and a first dielectric tangent of the capacitor for each of a plurality of equilibrium temperatures into the following equation:
• 14 Pe = tan ⁢ ⁢ δ 1 + ( tan ⁢ ⁢ δ ) 2 · π ⁢ ⁢ fCb 2
• Pe:
• effective power
• tan δ:
• dielectric tangent
• C:
• capacitance
• f:
• frequency
• b:
• sine-wave amplitude
• in order to obtain a first effective power for each of the equilibrium temperatures;
• obtaining a voltage value and a frequency from the waveform of a periodic voltage applied to both ends of the capacitor, and setting a plurality of provisional temperatures, and obtaining a second capacitance and a second dielectric tangent for each of the provisional temperatures, and substituting the second capacitance and the second dielectric tangent into the following equation:
• 15 Pe = tan ⁢ ⁢ δ 1 + ( tan ⁢ ⁢ δ ) 2 · π ⁢ fC ( a 2 + b 2 )
• Pe:
• effective power
• tan δ:
• dielectric tangent
• C:
• capacitance
• f:
• frequency
• a:
• cosine-wave amplitude
• b:
• sine-wave amplitude
• in order to obtain a second effective power corresponding to the periodic voltage for each of the provisional temperatures;
• determining a temperature at which the first effective power is approximately equal to the second effective power as a target equilibrium temperature of the capacitor, and determining the first and second effective powers corresponding to this target equilibrium temperature as a target effective power corresponding to the periodic voltage;
• and
• comparing the target effective power corresponding to the periodic voltage with an allowable power capacity of the capacitor in order to determine whether or not the capacitor is available.

A calculation apparatus for calculating effective power relating to a capacitor, comprising a calculator, wherein the calculator stores data on a plurality of capacitors including capacitances and dielectric tangents thereof which are determined based on a voltage characteristic, a frequency characteristic, and a temperature characteristic of the capacitors, and data on a first effective power for each of a plurality of equilibrium temperatures of the capacitors;

• when a predetermined capacitance required for an electric circuit using one of the capacitors and the waveform of a periodic voltage applied to both ends of the capacitor are input, a second effective power at each of a plurality of provisional temperatures is calculated from the input waveform of the periodic voltage;
• the calculator determines a predetermined temperature at which the first effective power is approximately equal to the second effective power as a target equilibrium temperature of the capacitor;
• the calculator determines the first effective power and the second effective power corresponding to the target equilibrium temperature as a target effective power corresponding to the periodic voltage;
• and
• the calculator compares a stored allowable power of the capacitor with the target effective power corresponding to the periodic voltage in order to determine whether or not the capacitor is available.

A recording medium storing a program for calculating effective power relating to a capacitor by using a computer, wherein the program stores data on a plurality of capacitors including capacitances and dielectric tangents thereof which are determined based on a voltage characteristic, a frequency characteristic, and a temperature characteristic of the capacitors, and data on a first effective power for each of a plurality of equilibrium temperatures of the capacitors,

• wherein when a predetermined capacitance required for an electric circuit using one of the capacitors and the waveform of a periodic voltage applied to both ends of the capacitor are input, the program calculates a second effective power at each of a plurality of provisional temperatures from the input waveform of the periodic voltage,
• wherein the program determines a predetermined temperature at which the first effective power is approximately equal to the second effective power as a target equilibrium temperature of the capacitor,
• wherein the program determines the first effective power and the second effective power corresponding to the target equilibrium temperature as a target effective power corresponding to the periodic voltage,
• wherein the program compares a stored allowable power of the capacitor with the target effective power corresponding to the periodic voltage in order to determine whether or not the capacitor is available.