3.4.7 D-Dissipation Factor or TANδ
To measure dissipation factor, the tester applies an AC voltage across the selected winding, and measures the voltage across and the current through the winding. Using harmonic analysis, the measured voltage is divided by the current to obtain a complex impedance from which the dissipation factor is obtained.
Choosing the test signal
For optimum accuracy and performance, use the test conditions chosen for capacitance in a later section of this chapter.
The test conditions can also be determined automatically by the AT3600 according to this table:
Note that a ‘fixed’ signal cannot be used with an ‘auto’ frequency.
To program the test using the PC Test Editor:
Choose the integration period (normally ‘Medium’) and enter the terminals to be measured.
Use the Editor’s ‘measure’ button (together with a sample part) if you are unsure of how to choose the test conditions.
Choosing the test limits
The test limits can be:
||A nominal value together with + and – percentage limits.
||Minimum and maximum values
||A minimum value only
||A maximum value only
Use the PC Editor’s ‘measure’ button (together with a sample part) if you are unsure of the nominal value.
Typically, D is tested against a maximum value. A typical film dielectric capacitor may have a D < 0.01. Because D is a ratio of two impedances it has no units.